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6115 lines
168 KiB
6115 lines
168 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* kernel/workqueue.c - generic async execution with shared worker pool |
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* |
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* Copyright (C) 2002 Ingo Molnar |
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* |
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* Derived from the taskqueue/keventd code by: |
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* David Woodhouse <[email protected]> |
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* Andrew Morton |
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* Kai Petzke <[email protected]> |
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* Theodore Ts'o <[email protected]> |
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* |
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* Made to use alloc_percpu by Christoph Lameter. |
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* |
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* Copyright (C) 2010 SUSE Linux Products GmbH |
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* Copyright (C) 2010 Tejun Heo <[email protected]> |
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* |
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* This is the generic async execution mechanism. Work items as are |
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* executed in process context. The worker pool is shared and |
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* automatically managed. There are two worker pools for each CPU (one for |
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* normal work items and the other for high priority ones) and some extra |
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* pools for workqueues which are not bound to any specific CPU - the |
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* number of these backing pools is dynamic. |
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* |
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* Please read Documentation/core-api/workqueue.rst for details. |
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*/ |
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|
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#include <linux/export.h> |
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#include <linux/kernel.h> |
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#include <linux/sched.h> |
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#include <linux/init.h> |
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#include <linux/signal.h> |
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#include <linux/completion.h> |
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#include <linux/workqueue.h> |
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#include <linux/slab.h> |
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#include <linux/cpu.h> |
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#include <linux/notifier.h> |
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#include <linux/kthread.h> |
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#include <linux/hardirq.h> |
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#include <linux/mempolicy.h> |
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#include <linux/freezer.h> |
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#include <linux/debug_locks.h> |
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#include <linux/lockdep.h> |
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#include <linux/idr.h> |
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#include <linux/jhash.h> |
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#include <linux/hashtable.h> |
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#include <linux/rculist.h> |
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#include <linux/nodemask.h> |
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#include <linux/moduleparam.h> |
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#include <linux/uaccess.h> |
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#include <linux/sched/isolation.h> |
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#include <linux/nmi.h> |
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#include <linux/kvm_para.h> |
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|
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#include "workqueue_internal.h" |
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enum { |
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/* |
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* worker_pool flags |
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* |
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* A bound pool is either associated or disassociated with its CPU. |
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* While associated (!DISASSOCIATED), all workers are bound to the |
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* CPU and none has %WORKER_UNBOUND set and concurrency management |
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* is in effect. |
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* |
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* While DISASSOCIATED, the cpu may be offline and all workers have |
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* %WORKER_UNBOUND set and concurrency management disabled, and may |
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* be executing on any CPU. The pool behaves as an unbound one. |
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* |
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* Note that DISASSOCIATED should be flipped only while holding |
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* wq_pool_attach_mutex to avoid changing binding state while |
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* worker_attach_to_pool() is in progress. |
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*/ |
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POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ |
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POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
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|
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/* worker flags */ |
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WORKER_DIE = 1 << 1, /* die die die */ |
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WORKER_IDLE = 1 << 2, /* is idle */ |
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WORKER_PREP = 1 << 3, /* preparing to run works */ |
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WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
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WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
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WORKER_REBOUND = 1 << 8, /* worker was rebound */ |
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WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | |
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WORKER_UNBOUND | WORKER_REBOUND, |
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NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
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UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ |
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BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
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MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
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IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
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MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
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/* call for help after 10ms |
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(min two ticks) */ |
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MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
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CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
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/* |
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* Rescue workers are used only on emergencies and shared by |
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* all cpus. Give MIN_NICE. |
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*/ |
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RESCUER_NICE_LEVEL = MIN_NICE, |
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HIGHPRI_NICE_LEVEL = MIN_NICE, |
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WQ_NAME_LEN = 24, |
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}; |
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/* |
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* Structure fields follow one of the following exclusion rules. |
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* |
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* I: Modifiable by initialization/destruction paths and read-only for |
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* everyone else. |
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* |
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* P: Preemption protected. Disabling preemption is enough and should |
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* only be modified and accessed from the local cpu. |
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* |
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* L: pool->lock protected. Access with pool->lock held. |
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* |
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* X: During normal operation, modification requires pool->lock and should |
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* be done only from local cpu. Either disabling preemption on local |
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* cpu or grabbing pool->lock is enough for read access. If |
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* POOL_DISASSOCIATED is set, it's identical to L. |
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* |
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* A: wq_pool_attach_mutex protected. |
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* |
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* PL: wq_pool_mutex protected. |
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* |
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* PR: wq_pool_mutex protected for writes. RCU protected for reads. |
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* |
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* PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. |
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* |
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* PWR: wq_pool_mutex and wq->mutex protected for writes. Either or |
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* RCU for reads. |
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* |
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* WQ: wq->mutex protected. |
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* |
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* WR: wq->mutex protected for writes. RCU protected for reads. |
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* |
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* MD: wq_mayday_lock protected. |
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*/ |
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/* struct worker is defined in workqueue_internal.h */ |
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struct worker_pool { |
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raw_spinlock_t lock; /* the pool lock */ |
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int cpu; /* I: the associated cpu */ |
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int node; /* I: the associated node ID */ |
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int id; /* I: pool ID */ |
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unsigned int flags; /* X: flags */ |
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unsigned long watchdog_ts; /* L: watchdog timestamp */ |
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struct list_head worklist; /* L: list of pending works */ |
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int nr_workers; /* L: total number of workers */ |
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int nr_idle; /* L: currently idle workers */ |
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struct list_head idle_list; /* X: list of idle workers */ |
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struct timer_list idle_timer; /* L: worker idle timeout */ |
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struct timer_list mayday_timer; /* L: SOS timer for workers */ |
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/* a workers is either on busy_hash or idle_list, or the manager */ |
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DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
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/* L: hash of busy workers */ |
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struct worker *manager; /* L: purely informational */ |
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struct list_head workers; /* A: attached workers */ |
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struct completion *detach_completion; /* all workers detached */ |
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struct ida worker_ida; /* worker IDs for task name */ |
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struct workqueue_attrs *attrs; /* I: worker attributes */ |
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struct hlist_node hash_node; /* PL: unbound_pool_hash node */ |
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int refcnt; /* PL: refcnt for unbound pools */ |
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/* |
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* The current concurrency level. As it's likely to be accessed |
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* from other CPUs during try_to_wake_up(), put it in a separate |
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* cacheline. |
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*/ |
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atomic_t nr_running ____cacheline_aligned_in_smp; |
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/* |
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* Destruction of pool is RCU protected to allow dereferences |
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* from get_work_pool(). |
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*/ |
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struct rcu_head rcu; |
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} ____cacheline_aligned_in_smp; |
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|
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/* |
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* The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
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* of work_struct->data are used for flags and the remaining high bits |
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* point to the pwq; thus, pwqs need to be aligned at two's power of the |
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* number of flag bits. |
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*/ |
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struct pool_workqueue { |
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struct worker_pool *pool; /* I: the associated pool */ |
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struct workqueue_struct *wq; /* I: the owning workqueue */ |
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int work_color; /* L: current color */ |
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int flush_color; /* L: flushing color */ |
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int refcnt; /* L: reference count */ |
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int nr_in_flight[WORK_NR_COLORS]; |
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/* L: nr of in_flight works */ |
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/* |
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* nr_active management and WORK_STRUCT_INACTIVE: |
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* |
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* When pwq->nr_active >= max_active, new work item is queued to |
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* pwq->inactive_works instead of pool->worklist and marked with |
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* WORK_STRUCT_INACTIVE. |
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* |
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* All work items marked with WORK_STRUCT_INACTIVE do not participate |
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* in pwq->nr_active and all work items in pwq->inactive_works are |
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* marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE |
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* work items are in pwq->inactive_works. Some of them are ready to |
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* run in pool->worklist or worker->scheduled. Those work itmes are |
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* only struct wq_barrier which is used for flush_work() and should |
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* not participate in pwq->nr_active. For non-barrier work item, it |
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* is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. |
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*/ |
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int nr_active; /* L: nr of active works */ |
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int max_active; /* L: max active works */ |
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struct list_head inactive_works; /* L: inactive works */ |
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struct list_head pwqs_node; /* WR: node on wq->pwqs */ |
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struct list_head mayday_node; /* MD: node on wq->maydays */ |
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/* |
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* Release of unbound pwq is punted to system_wq. See put_pwq() |
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* and pwq_unbound_release_workfn() for details. pool_workqueue |
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* itself is also RCU protected so that the first pwq can be |
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* determined without grabbing wq->mutex. |
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*/ |
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struct work_struct unbound_release_work; |
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struct rcu_head rcu; |
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} __aligned(1 << WORK_STRUCT_FLAG_BITS); |
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/* |
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* Structure used to wait for workqueue flush. |
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*/ |
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struct wq_flusher { |
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struct list_head list; /* WQ: list of flushers */ |
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int flush_color; /* WQ: flush color waiting for */ |
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struct completion done; /* flush completion */ |
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}; |
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struct wq_device; |
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/* |
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* The externally visible workqueue. It relays the issued work items to |
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* the appropriate worker_pool through its pool_workqueues. |
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*/ |
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struct workqueue_struct { |
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struct list_head pwqs; /* WR: all pwqs of this wq */ |
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struct list_head list; /* PR: list of all workqueues */ |
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struct mutex mutex; /* protects this wq */ |
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int work_color; /* WQ: current work color */ |
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int flush_color; /* WQ: current flush color */ |
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atomic_t nr_pwqs_to_flush; /* flush in progress */ |
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struct wq_flusher *first_flusher; /* WQ: first flusher */ |
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struct list_head flusher_queue; /* WQ: flush waiters */ |
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struct list_head flusher_overflow; /* WQ: flush overflow list */ |
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struct list_head maydays; /* MD: pwqs requesting rescue */ |
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struct worker *rescuer; /* MD: rescue worker */ |
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int nr_drainers; /* WQ: drain in progress */ |
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int saved_max_active; /* WQ: saved pwq max_active */ |
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struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ |
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struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ |
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#ifdef CONFIG_SYSFS |
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struct wq_device *wq_dev; /* I: for sysfs interface */ |
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#endif |
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#ifdef CONFIG_LOCKDEP |
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char *lock_name; |
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struct lock_class_key key; |
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struct lockdep_map lockdep_map; |
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#endif |
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char name[WQ_NAME_LEN]; /* I: workqueue name */ |
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/* |
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* Destruction of workqueue_struct is RCU protected to allow walking |
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* the workqueues list without grabbing wq_pool_mutex. |
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* This is used to dump all workqueues from sysrq. |
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*/ |
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struct rcu_head rcu; |
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/* hot fields used during command issue, aligned to cacheline */ |
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unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ |
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struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ |
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struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ |
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}; |
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static struct kmem_cache *pwq_cache; |
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static cpumask_var_t *wq_numa_possible_cpumask; |
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/* possible CPUs of each node */ |
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static bool wq_disable_numa; |
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module_param_named(disable_numa, wq_disable_numa, bool, 0444); |
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/* see the comment above the definition of WQ_POWER_EFFICIENT */ |
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static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); |
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module_param_named(power_efficient, wq_power_efficient, bool, 0444); |
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static bool wq_online; /* can kworkers be created yet? */ |
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static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ |
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/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ |
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static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; |
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static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ |
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static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ |
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static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ |
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/* wait for manager to go away */ |
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static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); |
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static LIST_HEAD(workqueues); /* PR: list of all workqueues */ |
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static bool workqueue_freezing; /* PL: have wqs started freezing? */ |
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/* PL: allowable cpus for unbound wqs and work items */ |
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static cpumask_var_t wq_unbound_cpumask; |
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/* CPU where unbound work was last round robin scheduled from this CPU */ |
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static DEFINE_PER_CPU(int, wq_rr_cpu_last); |
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/* |
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* Local execution of unbound work items is no longer guaranteed. The |
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* following always forces round-robin CPU selection on unbound work items |
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* to uncover usages which depend on it. |
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*/ |
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#ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU |
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static bool wq_debug_force_rr_cpu = true; |
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#else |
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static bool wq_debug_force_rr_cpu = false; |
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#endif |
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module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); |
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/* the per-cpu worker pools */ |
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); |
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static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ |
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/* PL: hash of all unbound pools keyed by pool->attrs */ |
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static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); |
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/* I: attributes used when instantiating standard unbound pools on demand */ |
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static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; |
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/* I: attributes used when instantiating ordered pools on demand */ |
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static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; |
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struct workqueue_struct *system_wq __read_mostly; |
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EXPORT_SYMBOL(system_wq); |
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struct workqueue_struct *system_highpri_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_highpri_wq); |
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struct workqueue_struct *system_long_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_long_wq); |
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struct workqueue_struct *system_unbound_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_unbound_wq); |
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struct workqueue_struct *system_freezable_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_freezable_wq); |
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struct workqueue_struct *system_power_efficient_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_power_efficient_wq); |
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struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; |
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EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); |
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static int worker_thread(void *__worker); |
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static void workqueue_sysfs_unregister(struct workqueue_struct *wq); |
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static void show_pwq(struct pool_workqueue *pwq); |
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#define CREATE_TRACE_POINTS |
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#include <trace/events/workqueue.h> |
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#define assert_rcu_or_pool_mutex() \ |
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RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
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!lockdep_is_held(&wq_pool_mutex), \ |
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"RCU or wq_pool_mutex should be held") |
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#define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ |
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RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
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!lockdep_is_held(&wq->mutex) && \ |
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!lockdep_is_held(&wq_pool_mutex), \ |
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"RCU, wq->mutex or wq_pool_mutex should be held") |
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#define for_each_cpu_worker_pool(pool, cpu) \ |
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for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ |
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(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ |
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(pool)++) |
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/** |
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* for_each_pool - iterate through all worker_pools in the system |
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* @pool: iteration cursor |
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* @pi: integer used for iteration |
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* |
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* This must be called either with wq_pool_mutex held or RCU read |
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* locked. If the pool needs to be used beyond the locking in effect, the |
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* caller is responsible for guaranteeing that the pool stays online. |
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* |
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* The if/else clause exists only for the lockdep assertion and can be |
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* ignored. |
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*/ |
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#define for_each_pool(pool, pi) \ |
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idr_for_each_entry(&worker_pool_idr, pool, pi) \ |
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if (({ assert_rcu_or_pool_mutex(); false; })) { } \ |
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else |
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/** |
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* for_each_pool_worker - iterate through all workers of a worker_pool |
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* @worker: iteration cursor |
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* @pool: worker_pool to iterate workers of |
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* |
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* This must be called with wq_pool_attach_mutex. |
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* |
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* The if/else clause exists only for the lockdep assertion and can be |
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* ignored. |
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*/ |
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#define for_each_pool_worker(worker, pool) \ |
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list_for_each_entry((worker), &(pool)->workers, node) \ |
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if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ |
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else |
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/** |
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* for_each_pwq - iterate through all pool_workqueues of the specified workqueue |
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* @pwq: iteration cursor |
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* @wq: the target workqueue |
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* |
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* This must be called either with wq->mutex held or RCU read locked. |
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* If the pwq needs to be used beyond the locking in effect, the caller is |
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* responsible for guaranteeing that the pwq stays online. |
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* |
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* The if/else clause exists only for the lockdep assertion and can be |
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* ignored. |
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*/ |
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#define for_each_pwq(pwq, wq) \ |
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list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ |
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lockdep_is_held(&(wq->mutex))) |
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#ifdef CONFIG_DEBUG_OBJECTS_WORK |
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static const struct debug_obj_descr work_debug_descr; |
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|
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static void *work_debug_hint(void *addr) |
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{ |
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return ((struct work_struct *) addr)->func; |
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} |
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static bool work_is_static_object(void *addr) |
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{ |
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struct work_struct *work = addr; |
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|
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return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); |
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} |
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|
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/* |
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* fixup_init is called when: |
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* - an active object is initialized |
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*/ |
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static bool work_fixup_init(void *addr, enum debug_obj_state state) |
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{ |
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struct work_struct *work = addr; |
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|
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switch (state) { |
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case ODEBUG_STATE_ACTIVE: |
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cancel_work_sync(work); |
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debug_object_init(work, &work_debug_descr); |
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return true; |
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default: |
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return false; |
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} |
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} |
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|
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/* |
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* fixup_free is called when: |
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* - an active object is freed |
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*/ |
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static bool work_fixup_free(void *addr, enum debug_obj_state state) |
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{ |
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struct work_struct *work = addr; |
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|
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switch (state) { |
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case ODEBUG_STATE_ACTIVE: |
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cancel_work_sync(work); |
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debug_object_free(work, &work_debug_descr); |
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return true; |
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default: |
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return false; |
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} |
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} |
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static const struct debug_obj_descr work_debug_descr = { |
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.name = "work_struct", |
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.debug_hint = work_debug_hint, |
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.is_static_object = work_is_static_object, |
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.fixup_init = work_fixup_init, |
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.fixup_free = work_fixup_free, |
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}; |
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static inline void debug_work_activate(struct work_struct *work) |
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{ |
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debug_object_activate(work, &work_debug_descr); |
|
} |
|
|
|
static inline void debug_work_deactivate(struct work_struct *work) |
|
{ |
|
debug_object_deactivate(work, &work_debug_descr); |
|
} |
|
|
|
void __init_work(struct work_struct *work, int onstack) |
|
{ |
|
if (onstack) |
|
debug_object_init_on_stack(work, &work_debug_descr); |
|
else |
|
debug_object_init(work, &work_debug_descr); |
|
} |
|
EXPORT_SYMBOL_GPL(__init_work); |
|
|
|
void destroy_work_on_stack(struct work_struct *work) |
|
{ |
|
debug_object_free(work, &work_debug_descr); |
|
} |
|
EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
|
|
|
void destroy_delayed_work_on_stack(struct delayed_work *work) |
|
{ |
|
destroy_timer_on_stack(&work->timer); |
|
debug_object_free(&work->work, &work_debug_descr); |
|
} |
|
EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); |
|
|
|
#else |
|
static inline void debug_work_activate(struct work_struct *work) { } |
|
static inline void debug_work_deactivate(struct work_struct *work) { } |
|
#endif |
|
|
|
/** |
|
* worker_pool_assign_id - allocate ID and assign it to @pool |
|
* @pool: the pool pointer of interest |
|
* |
|
* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned |
|
* successfully, -errno on failure. |
|
*/ |
|
static int worker_pool_assign_id(struct worker_pool *pool) |
|
{ |
|
int ret; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, |
|
GFP_KERNEL); |
|
if (ret >= 0) { |
|
pool->id = ret; |
|
return 0; |
|
} |
|
return ret; |
|
} |
|
|
|
/** |
|
* unbound_pwq_by_node - return the unbound pool_workqueue for the given node |
|
* @wq: the target workqueue |
|
* @node: the node ID |
|
* |
|
* This must be called with any of wq_pool_mutex, wq->mutex or RCU |
|
* read locked. |
|
* If the pwq needs to be used beyond the locking in effect, the caller is |
|
* responsible for guaranteeing that the pwq stays online. |
|
* |
|
* Return: The unbound pool_workqueue for @node. |
|
*/ |
|
static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, |
|
int node) |
|
{ |
|
assert_rcu_or_wq_mutex_or_pool_mutex(wq); |
|
|
|
/* |
|
* XXX: @node can be NUMA_NO_NODE if CPU goes offline while a |
|
* delayed item is pending. The plan is to keep CPU -> NODE |
|
* mapping valid and stable across CPU on/offlines. Once that |
|
* happens, this workaround can be removed. |
|
*/ |
|
if (unlikely(node == NUMA_NO_NODE)) |
|
return wq->dfl_pwq; |
|
|
|
return rcu_dereference_raw(wq->numa_pwq_tbl[node]); |
|
} |
|
|
|
static unsigned int work_color_to_flags(int color) |
|
{ |
|
return color << WORK_STRUCT_COLOR_SHIFT; |
|
} |
|
|
|
static int get_work_color(unsigned long work_data) |
|
{ |
|
return (work_data >> WORK_STRUCT_COLOR_SHIFT) & |
|
((1 << WORK_STRUCT_COLOR_BITS) - 1); |
|
} |
|
|
|
static int work_next_color(int color) |
|
{ |
|
return (color + 1) % WORK_NR_COLORS; |
|
} |
|
|
|
/* |
|
* While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
|
* contain the pointer to the queued pwq. Once execution starts, the flag |
|
* is cleared and the high bits contain OFFQ flags and pool ID. |
|
* |
|
* set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
|
* and clear_work_data() can be used to set the pwq, pool or clear |
|
* work->data. These functions should only be called while the work is |
|
* owned - ie. while the PENDING bit is set. |
|
* |
|
* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
|
* corresponding to a work. Pool is available once the work has been |
|
* queued anywhere after initialization until it is sync canceled. pwq is |
|
* available only while the work item is queued. |
|
* |
|
* %WORK_OFFQ_CANCELING is used to mark a work item which is being |
|
* canceled. While being canceled, a work item may have its PENDING set |
|
* but stay off timer and worklist for arbitrarily long and nobody should |
|
* try to steal the PENDING bit. |
|
*/ |
|
static inline void set_work_data(struct work_struct *work, unsigned long data, |
|
unsigned long flags) |
|
{ |
|
WARN_ON_ONCE(!work_pending(work)); |
|
atomic_long_set(&work->data, data | flags | work_static(work)); |
|
} |
|
|
|
static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
|
unsigned long extra_flags) |
|
{ |
|
set_work_data(work, (unsigned long)pwq, |
|
WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); |
|
} |
|
|
|
static void set_work_pool_and_keep_pending(struct work_struct *work, |
|
int pool_id) |
|
{ |
|
set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, |
|
WORK_STRUCT_PENDING); |
|
} |
|
|
|
static void set_work_pool_and_clear_pending(struct work_struct *work, |
|
int pool_id) |
|
{ |
|
/* |
|
* The following wmb is paired with the implied mb in |
|
* test_and_set_bit(PENDING) and ensures all updates to @work made |
|
* here are visible to and precede any updates by the next PENDING |
|
* owner. |
|
*/ |
|
smp_wmb(); |
|
set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); |
|
/* |
|
* The following mb guarantees that previous clear of a PENDING bit |
|
* will not be reordered with any speculative LOADS or STORES from |
|
* work->current_func, which is executed afterwards. This possible |
|
* reordering can lead to a missed execution on attempt to queue |
|
* the same @work. E.g. consider this case: |
|
* |
|
* CPU#0 CPU#1 |
|
* ---------------------------- -------------------------------- |
|
* |
|
* 1 STORE event_indicated |
|
* 2 queue_work_on() { |
|
* 3 test_and_set_bit(PENDING) |
|
* 4 } set_..._and_clear_pending() { |
|
* 5 set_work_data() # clear bit |
|
* 6 smp_mb() |
|
* 7 work->current_func() { |
|
* 8 LOAD event_indicated |
|
* } |
|
* |
|
* Without an explicit full barrier speculative LOAD on line 8 can |
|
* be executed before CPU#0 does STORE on line 1. If that happens, |
|
* CPU#0 observes the PENDING bit is still set and new execution of |
|
* a @work is not queued in a hope, that CPU#1 will eventually |
|
* finish the queued @work. Meanwhile CPU#1 does not see |
|
* event_indicated is set, because speculative LOAD was executed |
|
* before actual STORE. |
|
*/ |
|
smp_mb(); |
|
} |
|
|
|
static void clear_work_data(struct work_struct *work) |
|
{ |
|
smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
|
set_work_data(work, WORK_STRUCT_NO_POOL, 0); |
|
} |
|
|
|
static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
|
{ |
|
unsigned long data = atomic_long_read(&work->data); |
|
|
|
if (data & WORK_STRUCT_PWQ) |
|
return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
|
else |
|
return NULL; |
|
} |
|
|
|
/** |
|
* get_work_pool - return the worker_pool a given work was associated with |
|
* @work: the work item of interest |
|
* |
|
* Pools are created and destroyed under wq_pool_mutex, and allows read |
|
* access under RCU read lock. As such, this function should be |
|
* called under wq_pool_mutex or inside of a rcu_read_lock() region. |
|
* |
|
* All fields of the returned pool are accessible as long as the above |
|
* mentioned locking is in effect. If the returned pool needs to be used |
|
* beyond the critical section, the caller is responsible for ensuring the |
|
* returned pool is and stays online. |
|
* |
|
* Return: The worker_pool @work was last associated with. %NULL if none. |
|
*/ |
|
static struct worker_pool *get_work_pool(struct work_struct *work) |
|
{ |
|
unsigned long data = atomic_long_read(&work->data); |
|
int pool_id; |
|
|
|
assert_rcu_or_pool_mutex(); |
|
|
|
if (data & WORK_STRUCT_PWQ) |
|
return ((struct pool_workqueue *) |
|
(data & WORK_STRUCT_WQ_DATA_MASK))->pool; |
|
|
|
pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
|
if (pool_id == WORK_OFFQ_POOL_NONE) |
|
return NULL; |
|
|
|
return idr_find(&worker_pool_idr, pool_id); |
|
} |
|
|
|
/** |
|
* get_work_pool_id - return the worker pool ID a given work is associated with |
|
* @work: the work item of interest |
|
* |
|
* Return: The worker_pool ID @work was last associated with. |
|
* %WORK_OFFQ_POOL_NONE if none. |
|
*/ |
|
static int get_work_pool_id(struct work_struct *work) |
|
{ |
|
unsigned long data = atomic_long_read(&work->data); |
|
|
|
if (data & WORK_STRUCT_PWQ) |
|
return ((struct pool_workqueue *) |
|
(data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; |
|
|
|
return data >> WORK_OFFQ_POOL_SHIFT; |
|
} |
|
|
|
static void mark_work_canceling(struct work_struct *work) |
|
{ |
|
unsigned long pool_id = get_work_pool_id(work); |
|
|
|
pool_id <<= WORK_OFFQ_POOL_SHIFT; |
|
set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); |
|
} |
|
|
|
static bool work_is_canceling(struct work_struct *work) |
|
{ |
|
unsigned long data = atomic_long_read(&work->data); |
|
|
|
return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
|
} |
|
|
|
/* |
|
* Policy functions. These define the policies on how the global worker |
|
* pools are managed. Unless noted otherwise, these functions assume that |
|
* they're being called with pool->lock held. |
|
*/ |
|
|
|
static bool __need_more_worker(struct worker_pool *pool) |
|
{ |
|
return !atomic_read(&pool->nr_running); |
|
} |
|
|
|
/* |
|
* Need to wake up a worker? Called from anything but currently |
|
* running workers. |
|
* |
|
* Note that, because unbound workers never contribute to nr_running, this |
|
* function will always return %true for unbound pools as long as the |
|
* worklist isn't empty. |
|
*/ |
|
static bool need_more_worker(struct worker_pool *pool) |
|
{ |
|
return !list_empty(&pool->worklist) && __need_more_worker(pool); |
|
} |
|
|
|
/* Can I start working? Called from busy but !running workers. */ |
|
static bool may_start_working(struct worker_pool *pool) |
|
{ |
|
return pool->nr_idle; |
|
} |
|
|
|
/* Do I need to keep working? Called from currently running workers. */ |
|
static bool keep_working(struct worker_pool *pool) |
|
{ |
|
return !list_empty(&pool->worklist) && |
|
atomic_read(&pool->nr_running) <= 1; |
|
} |
|
|
|
/* Do we need a new worker? Called from manager. */ |
|
static bool need_to_create_worker(struct worker_pool *pool) |
|
{ |
|
return need_more_worker(pool) && !may_start_working(pool); |
|
} |
|
|
|
/* Do we have too many workers and should some go away? */ |
|
static bool too_many_workers(struct worker_pool *pool) |
|
{ |
|
bool managing = pool->flags & POOL_MANAGER_ACTIVE; |
|
int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
|
int nr_busy = pool->nr_workers - nr_idle; |
|
|
|
return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
|
} |
|
|
|
/* |
|
* Wake up functions. |
|
*/ |
|
|
|
/* Return the first idle worker. Safe with preemption disabled */ |
|
static struct worker *first_idle_worker(struct worker_pool *pool) |
|
{ |
|
if (unlikely(list_empty(&pool->idle_list))) |
|
return NULL; |
|
|
|
return list_first_entry(&pool->idle_list, struct worker, entry); |
|
} |
|
|
|
/** |
|
* wake_up_worker - wake up an idle worker |
|
* @pool: worker pool to wake worker from |
|
* |
|
* Wake up the first idle worker of @pool. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void wake_up_worker(struct worker_pool *pool) |
|
{ |
|
struct worker *worker = first_idle_worker(pool); |
|
|
|
if (likely(worker)) |
|
wake_up_process(worker->task); |
|
} |
|
|
|
/** |
|
* wq_worker_running - a worker is running again |
|
* @task: task waking up |
|
* |
|
* This function is called when a worker returns from schedule() |
|
*/ |
|
void wq_worker_running(struct task_struct *task) |
|
{ |
|
struct worker *worker = kthread_data(task); |
|
|
|
if (!worker->sleeping) |
|
return; |
|
if (!(worker->flags & WORKER_NOT_RUNNING)) |
|
atomic_inc(&worker->pool->nr_running); |
|
worker->sleeping = 0; |
|
} |
|
|
|
/** |
|
* wq_worker_sleeping - a worker is going to sleep |
|
* @task: task going to sleep |
|
* |
|
* This function is called from schedule() when a busy worker is |
|
* going to sleep. Preemption needs to be disabled to protect ->sleeping |
|
* assignment. |
|
*/ |
|
void wq_worker_sleeping(struct task_struct *task) |
|
{ |
|
struct worker *next, *worker = kthread_data(task); |
|
struct worker_pool *pool; |
|
|
|
/* |
|
* Rescuers, which may not have all the fields set up like normal |
|
* workers, also reach here, let's not access anything before |
|
* checking NOT_RUNNING. |
|
*/ |
|
if (worker->flags & WORKER_NOT_RUNNING) |
|
return; |
|
|
|
pool = worker->pool; |
|
|
|
/* Return if preempted before wq_worker_running() was reached */ |
|
if (worker->sleeping) |
|
return; |
|
|
|
worker->sleeping = 1; |
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
/* |
|
* The counterpart of the following dec_and_test, implied mb, |
|
* worklist not empty test sequence is in insert_work(). |
|
* Please read comment there. |
|
* |
|
* NOT_RUNNING is clear. This means that we're bound to and |
|
* running on the local cpu w/ rq lock held and preemption |
|
* disabled, which in turn means that none else could be |
|
* manipulating idle_list, so dereferencing idle_list without pool |
|
* lock is safe. |
|
*/ |
|
if (atomic_dec_and_test(&pool->nr_running) && |
|
!list_empty(&pool->worklist)) { |
|
next = first_idle_worker(pool); |
|
if (next) |
|
wake_up_process(next->task); |
|
} |
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
|
|
/** |
|
* wq_worker_last_func - retrieve worker's last work function |
|
* @task: Task to retrieve last work function of. |
|
* |
|
* Determine the last function a worker executed. This is called from |
|
* the scheduler to get a worker's last known identity. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(rq->lock) |
|
* |
|
* This function is called during schedule() when a kworker is going |
|
* to sleep. It's used by psi to identify aggregation workers during |
|
* dequeuing, to allow periodic aggregation to shut-off when that |
|
* worker is the last task in the system or cgroup to go to sleep. |
|
* |
|
* As this function doesn't involve any workqueue-related locking, it |
|
* only returns stable values when called from inside the scheduler's |
|
* queuing and dequeuing paths, when @task, which must be a kworker, |
|
* is guaranteed to not be processing any works. |
|
* |
|
* Return: |
|
* The last work function %current executed as a worker, NULL if it |
|
* hasn't executed any work yet. |
|
*/ |
|
work_func_t wq_worker_last_func(struct task_struct *task) |
|
{ |
|
struct worker *worker = kthread_data(task); |
|
|
|
return worker->last_func; |
|
} |
|
|
|
/** |
|
* worker_set_flags - set worker flags and adjust nr_running accordingly |
|
* @worker: self |
|
* @flags: flags to set |
|
* |
|
* Set @flags in @worker->flags and adjust nr_running accordingly. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock) |
|
*/ |
|
static inline void worker_set_flags(struct worker *worker, unsigned int flags) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
|
|
WARN_ON_ONCE(worker->task != current); |
|
|
|
/* If transitioning into NOT_RUNNING, adjust nr_running. */ |
|
if ((flags & WORKER_NOT_RUNNING) && |
|
!(worker->flags & WORKER_NOT_RUNNING)) { |
|
atomic_dec(&pool->nr_running); |
|
} |
|
|
|
worker->flags |= flags; |
|
} |
|
|
|
/** |
|
* worker_clr_flags - clear worker flags and adjust nr_running accordingly |
|
* @worker: self |
|
* @flags: flags to clear |
|
* |
|
* Clear @flags in @worker->flags and adjust nr_running accordingly. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock) |
|
*/ |
|
static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
unsigned int oflags = worker->flags; |
|
|
|
WARN_ON_ONCE(worker->task != current); |
|
|
|
worker->flags &= ~flags; |
|
|
|
/* |
|
* If transitioning out of NOT_RUNNING, increment nr_running. Note |
|
* that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
|
* of multiple flags, not a single flag. |
|
*/ |
|
if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
|
if (!(worker->flags & WORKER_NOT_RUNNING)) |
|
atomic_inc(&pool->nr_running); |
|
} |
|
|
|
/** |
|
* find_worker_executing_work - find worker which is executing a work |
|
* @pool: pool of interest |
|
* @work: work to find worker for |
|
* |
|
* Find a worker which is executing @work on @pool by searching |
|
* @pool->busy_hash which is keyed by the address of @work. For a worker |
|
* to match, its current execution should match the address of @work and |
|
* its work function. This is to avoid unwanted dependency between |
|
* unrelated work executions through a work item being recycled while still |
|
* being executed. |
|
* |
|
* This is a bit tricky. A work item may be freed once its execution |
|
* starts and nothing prevents the freed area from being recycled for |
|
* another work item. If the same work item address ends up being reused |
|
* before the original execution finishes, workqueue will identify the |
|
* recycled work item as currently executing and make it wait until the |
|
* current execution finishes, introducing an unwanted dependency. |
|
* |
|
* This function checks the work item address and work function to avoid |
|
* false positives. Note that this isn't complete as one may construct a |
|
* work function which can introduce dependency onto itself through a |
|
* recycled work item. Well, if somebody wants to shoot oneself in the |
|
* foot that badly, there's only so much we can do, and if such deadlock |
|
* actually occurs, it should be easy to locate the culprit work function. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
* |
|
* Return: |
|
* Pointer to worker which is executing @work if found, %NULL |
|
* otherwise. |
|
*/ |
|
static struct worker *find_worker_executing_work(struct worker_pool *pool, |
|
struct work_struct *work) |
|
{ |
|
struct worker *worker; |
|
|
|
hash_for_each_possible(pool->busy_hash, worker, hentry, |
|
(unsigned long)work) |
|
if (worker->current_work == work && |
|
worker->current_func == work->func) |
|
return worker; |
|
|
|
return NULL; |
|
} |
|
|
|
/** |
|
* move_linked_works - move linked works to a list |
|
* @work: start of series of works to be scheduled |
|
* @head: target list to append @work to |
|
* @nextp: out parameter for nested worklist walking |
|
* |
|
* Schedule linked works starting from @work to @head. Work series to |
|
* be scheduled starts at @work and includes any consecutive work with |
|
* WORK_STRUCT_LINKED set in its predecessor. |
|
* |
|
* If @nextp is not NULL, it's updated to point to the next work of |
|
* the last scheduled work. This allows move_linked_works() to be |
|
* nested inside outer list_for_each_entry_safe(). |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void move_linked_works(struct work_struct *work, struct list_head *head, |
|
struct work_struct **nextp) |
|
{ |
|
struct work_struct *n; |
|
|
|
/* |
|
* Linked worklist will always end before the end of the list, |
|
* use NULL for list head. |
|
*/ |
|
list_for_each_entry_safe_from(work, n, NULL, entry) { |
|
list_move_tail(&work->entry, head); |
|
if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
|
break; |
|
} |
|
|
|
/* |
|
* If we're already inside safe list traversal and have moved |
|
* multiple works to the scheduled queue, the next position |
|
* needs to be updated. |
|
*/ |
|
if (nextp) |
|
*nextp = n; |
|
} |
|
|
|
/** |
|
* get_pwq - get an extra reference on the specified pool_workqueue |
|
* @pwq: pool_workqueue to get |
|
* |
|
* Obtain an extra reference on @pwq. The caller should guarantee that |
|
* @pwq has positive refcnt and be holding the matching pool->lock. |
|
*/ |
|
static void get_pwq(struct pool_workqueue *pwq) |
|
{ |
|
lockdep_assert_held(&pwq->pool->lock); |
|
WARN_ON_ONCE(pwq->refcnt <= 0); |
|
pwq->refcnt++; |
|
} |
|
|
|
/** |
|
* put_pwq - put a pool_workqueue reference |
|
* @pwq: pool_workqueue to put |
|
* |
|
* Drop a reference of @pwq. If its refcnt reaches zero, schedule its |
|
* destruction. The caller should be holding the matching pool->lock. |
|
*/ |
|
static void put_pwq(struct pool_workqueue *pwq) |
|
{ |
|
lockdep_assert_held(&pwq->pool->lock); |
|
if (likely(--pwq->refcnt)) |
|
return; |
|
if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) |
|
return; |
|
/* |
|
* @pwq can't be released under pool->lock, bounce to |
|
* pwq_unbound_release_workfn(). This never recurses on the same |
|
* pool->lock as this path is taken only for unbound workqueues and |
|
* the release work item is scheduled on a per-cpu workqueue. To |
|
* avoid lockdep warning, unbound pool->locks are given lockdep |
|
* subclass of 1 in get_unbound_pool(). |
|
*/ |
|
schedule_work(&pwq->unbound_release_work); |
|
} |
|
|
|
/** |
|
* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock |
|
* @pwq: pool_workqueue to put (can be %NULL) |
|
* |
|
* put_pwq() with locking. This function also allows %NULL @pwq. |
|
*/ |
|
static void put_pwq_unlocked(struct pool_workqueue *pwq) |
|
{ |
|
if (pwq) { |
|
/* |
|
* As both pwqs and pools are RCU protected, the |
|
* following lock operations are safe. |
|
*/ |
|
raw_spin_lock_irq(&pwq->pool->lock); |
|
put_pwq(pwq); |
|
raw_spin_unlock_irq(&pwq->pool->lock); |
|
} |
|
} |
|
|
|
static void pwq_activate_inactive_work(struct work_struct *work) |
|
{ |
|
struct pool_workqueue *pwq = get_work_pwq(work); |
|
|
|
trace_workqueue_activate_work(work); |
|
if (list_empty(&pwq->pool->worklist)) |
|
pwq->pool->watchdog_ts = jiffies; |
|
move_linked_works(work, &pwq->pool->worklist, NULL); |
|
__clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work)); |
|
pwq->nr_active++; |
|
} |
|
|
|
static void pwq_activate_first_inactive(struct pool_workqueue *pwq) |
|
{ |
|
struct work_struct *work = list_first_entry(&pwq->inactive_works, |
|
struct work_struct, entry); |
|
|
|
pwq_activate_inactive_work(work); |
|
} |
|
|
|
/** |
|
* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
|
* @pwq: pwq of interest |
|
* @work_data: work_data of work which left the queue |
|
* |
|
* A work either has completed or is removed from pending queue, |
|
* decrement nr_in_flight of its pwq and handle workqueue flushing. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) |
|
{ |
|
int color = get_work_color(work_data); |
|
|
|
if (!(work_data & WORK_STRUCT_INACTIVE)) { |
|
pwq->nr_active--; |
|
if (!list_empty(&pwq->inactive_works)) { |
|
/* one down, submit an inactive one */ |
|
if (pwq->nr_active < pwq->max_active) |
|
pwq_activate_first_inactive(pwq); |
|
} |
|
} |
|
|
|
pwq->nr_in_flight[color]--; |
|
|
|
/* is flush in progress and are we at the flushing tip? */ |
|
if (likely(pwq->flush_color != color)) |
|
goto out_put; |
|
|
|
/* are there still in-flight works? */ |
|
if (pwq->nr_in_flight[color]) |
|
goto out_put; |
|
|
|
/* this pwq is done, clear flush_color */ |
|
pwq->flush_color = -1; |
|
|
|
/* |
|
* If this was the last pwq, wake up the first flusher. It |
|
* will handle the rest. |
|
*/ |
|
if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) |
|
complete(&pwq->wq->first_flusher->done); |
|
out_put: |
|
put_pwq(pwq); |
|
} |
|
|
|
/** |
|
* try_to_grab_pending - steal work item from worklist and disable irq |
|
* @work: work item to steal |
|
* @is_dwork: @work is a delayed_work |
|
* @flags: place to store irq state |
|
* |
|
* Try to grab PENDING bit of @work. This function can handle @work in any |
|
* stable state - idle, on timer or on worklist. |
|
* |
|
* Return: |
|
* |
|
* ======== ================================================================ |
|
* 1 if @work was pending and we successfully stole PENDING |
|
* 0 if @work was idle and we claimed PENDING |
|
* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry |
|
* -ENOENT if someone else is canceling @work, this state may persist |
|
* for arbitrarily long |
|
* ======== ================================================================ |
|
* |
|
* Note: |
|
* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
|
* interrupted while holding PENDING and @work off queue, irq must be |
|
* disabled on entry. This, combined with delayed_work->timer being |
|
* irqsafe, ensures that we return -EAGAIN for finite short period of time. |
|
* |
|
* On successful return, >= 0, irq is disabled and the caller is |
|
* responsible for releasing it using local_irq_restore(*@flags). |
|
* |
|
* This function is safe to call from any context including IRQ handler. |
|
*/ |
|
static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
|
unsigned long *flags) |
|
{ |
|
struct worker_pool *pool; |
|
struct pool_workqueue *pwq; |
|
|
|
local_irq_save(*flags); |
|
|
|
/* try to steal the timer if it exists */ |
|
if (is_dwork) { |
|
struct delayed_work *dwork = to_delayed_work(work); |
|
|
|
/* |
|
* dwork->timer is irqsafe. If del_timer() fails, it's |
|
* guaranteed that the timer is not queued anywhere and not |
|
* running on the local CPU. |
|
*/ |
|
if (likely(del_timer(&dwork->timer))) |
|
return 1; |
|
} |
|
|
|
/* try to claim PENDING the normal way */ |
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
|
return 0; |
|
|
|
rcu_read_lock(); |
|
/* |
|
* The queueing is in progress, or it is already queued. Try to |
|
* steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
|
*/ |
|
pool = get_work_pool(work); |
|
if (!pool) |
|
goto fail; |
|
|
|
raw_spin_lock(&pool->lock); |
|
/* |
|
* work->data is guaranteed to point to pwq only while the work |
|
* item is queued on pwq->wq, and both updating work->data to point |
|
* to pwq on queueing and to pool on dequeueing are done under |
|
* pwq->pool->lock. This in turn guarantees that, if work->data |
|
* points to pwq which is associated with a locked pool, the work |
|
* item is currently queued on that pool. |
|
*/ |
|
pwq = get_work_pwq(work); |
|
if (pwq && pwq->pool == pool) { |
|
debug_work_deactivate(work); |
|
|
|
/* |
|
* A cancelable inactive work item must be in the |
|
* pwq->inactive_works since a queued barrier can't be |
|
* canceled (see the comments in insert_wq_barrier()). |
|
* |
|
* An inactive work item cannot be grabbed directly because |
|
* it might have linked barrier work items which, if left |
|
* on the inactive_works list, will confuse pwq->nr_active |
|
* management later on and cause stall. Make sure the work |
|
* item is activated before grabbing. |
|
*/ |
|
if (*work_data_bits(work) & WORK_STRUCT_INACTIVE) |
|
pwq_activate_inactive_work(work); |
|
|
|
list_del_init(&work->entry); |
|
pwq_dec_nr_in_flight(pwq, *work_data_bits(work)); |
|
|
|
/* work->data points to pwq iff queued, point to pool */ |
|
set_work_pool_and_keep_pending(work, pool->id); |
|
|
|
raw_spin_unlock(&pool->lock); |
|
rcu_read_unlock(); |
|
return 1; |
|
} |
|
raw_spin_unlock(&pool->lock); |
|
fail: |
|
rcu_read_unlock(); |
|
local_irq_restore(*flags); |
|
if (work_is_canceling(work)) |
|
return -ENOENT; |
|
cpu_relax(); |
|
return -EAGAIN; |
|
} |
|
|
|
/** |
|
* insert_work - insert a work into a pool |
|
* @pwq: pwq @work belongs to |
|
* @work: work to insert |
|
* @head: insertion point |
|
* @extra_flags: extra WORK_STRUCT_* flags to set |
|
* |
|
* Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
|
* work_struct flags. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
|
struct list_head *head, unsigned int extra_flags) |
|
{ |
|
struct worker_pool *pool = pwq->pool; |
|
|
|
/* record the work call stack in order to print it in KASAN reports */ |
|
kasan_record_aux_stack(work); |
|
|
|
/* we own @work, set data and link */ |
|
set_work_pwq(work, pwq, extra_flags); |
|
list_add_tail(&work->entry, head); |
|
get_pwq(pwq); |
|
|
|
/* |
|
* Ensure either wq_worker_sleeping() sees the above |
|
* list_add_tail() or we see zero nr_running to avoid workers lying |
|
* around lazily while there are works to be processed. |
|
*/ |
|
smp_mb(); |
|
|
|
if (__need_more_worker(pool)) |
|
wake_up_worker(pool); |
|
} |
|
|
|
/* |
|
* Test whether @work is being queued from another work executing on the |
|
* same workqueue. |
|
*/ |
|
static bool is_chained_work(struct workqueue_struct *wq) |
|
{ |
|
struct worker *worker; |
|
|
|
worker = current_wq_worker(); |
|
/* |
|
* Return %true iff I'm a worker executing a work item on @wq. If |
|
* I'm @worker, it's safe to dereference it without locking. |
|
*/ |
|
return worker && worker->current_pwq->wq == wq; |
|
} |
|
|
|
/* |
|
* When queueing an unbound work item to a wq, prefer local CPU if allowed |
|
* by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to |
|
* avoid perturbing sensitive tasks. |
|
*/ |
|
static int wq_select_unbound_cpu(int cpu) |
|
{ |
|
static bool printed_dbg_warning; |
|
int new_cpu; |
|
|
|
if (likely(!wq_debug_force_rr_cpu)) { |
|
if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) |
|
return cpu; |
|
} else if (!printed_dbg_warning) { |
|
pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n"); |
|
printed_dbg_warning = true; |
|
} |
|
|
|
if (cpumask_empty(wq_unbound_cpumask)) |
|
return cpu; |
|
|
|
new_cpu = __this_cpu_read(wq_rr_cpu_last); |
|
new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); |
|
if (unlikely(new_cpu >= nr_cpu_ids)) { |
|
new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); |
|
if (unlikely(new_cpu >= nr_cpu_ids)) |
|
return cpu; |
|
} |
|
__this_cpu_write(wq_rr_cpu_last, new_cpu); |
|
|
|
return new_cpu; |
|
} |
|
|
|
static void __queue_work(int cpu, struct workqueue_struct *wq, |
|
struct work_struct *work) |
|
{ |
|
struct pool_workqueue *pwq; |
|
struct worker_pool *last_pool; |
|
struct list_head *worklist; |
|
unsigned int work_flags; |
|
unsigned int req_cpu = cpu; |
|
|
|
/* |
|
* While a work item is PENDING && off queue, a task trying to |
|
* steal the PENDING will busy-loop waiting for it to either get |
|
* queued or lose PENDING. Grabbing PENDING and queueing should |
|
* happen with IRQ disabled. |
|
*/ |
|
lockdep_assert_irqs_disabled(); |
|
|
|
|
|
/* if draining, only works from the same workqueue are allowed */ |
|
if (unlikely(wq->flags & __WQ_DRAINING) && |
|
WARN_ON_ONCE(!is_chained_work(wq))) |
|
return; |
|
rcu_read_lock(); |
|
retry: |
|
/* pwq which will be used unless @work is executing elsewhere */ |
|
if (wq->flags & WQ_UNBOUND) { |
|
if (req_cpu == WORK_CPU_UNBOUND) |
|
cpu = wq_select_unbound_cpu(raw_smp_processor_id()); |
|
pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
|
} else { |
|
if (req_cpu == WORK_CPU_UNBOUND) |
|
cpu = raw_smp_processor_id(); |
|
pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
|
} |
|
|
|
/* |
|
* If @work was previously on a different pool, it might still be |
|
* running there, in which case the work needs to be queued on that |
|
* pool to guarantee non-reentrancy. |
|
*/ |
|
last_pool = get_work_pool(work); |
|
if (last_pool && last_pool != pwq->pool) { |
|
struct worker *worker; |
|
|
|
raw_spin_lock(&last_pool->lock); |
|
|
|
worker = find_worker_executing_work(last_pool, work); |
|
|
|
if (worker && worker->current_pwq->wq == wq) { |
|
pwq = worker->current_pwq; |
|
} else { |
|
/* meh... not running there, queue here */ |
|
raw_spin_unlock(&last_pool->lock); |
|
raw_spin_lock(&pwq->pool->lock); |
|
} |
|
} else { |
|
raw_spin_lock(&pwq->pool->lock); |
|
} |
|
|
|
/* |
|
* pwq is determined and locked. For unbound pools, we could have |
|
* raced with pwq release and it could already be dead. If its |
|
* refcnt is zero, repeat pwq selection. Note that pwqs never die |
|
* without another pwq replacing it in the numa_pwq_tbl or while |
|
* work items are executing on it, so the retrying is guaranteed to |
|
* make forward-progress. |
|
*/ |
|
if (unlikely(!pwq->refcnt)) { |
|
if (wq->flags & WQ_UNBOUND) { |
|
raw_spin_unlock(&pwq->pool->lock); |
|
cpu_relax(); |
|
goto retry; |
|
} |
|
/* oops */ |
|
WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", |
|
wq->name, cpu); |
|
} |
|
|
|
/* pwq determined, queue */ |
|
trace_workqueue_queue_work(req_cpu, pwq, work); |
|
|
|
if (WARN_ON(!list_empty(&work->entry))) |
|
goto out; |
|
|
|
pwq->nr_in_flight[pwq->work_color]++; |
|
work_flags = work_color_to_flags(pwq->work_color); |
|
|
|
if (likely(pwq->nr_active < pwq->max_active)) { |
|
trace_workqueue_activate_work(work); |
|
pwq->nr_active++; |
|
worklist = &pwq->pool->worklist; |
|
if (list_empty(worklist)) |
|
pwq->pool->watchdog_ts = jiffies; |
|
} else { |
|
work_flags |= WORK_STRUCT_INACTIVE; |
|
worklist = &pwq->inactive_works; |
|
} |
|
|
|
debug_work_activate(work); |
|
insert_work(pwq, work, worklist, work_flags); |
|
|
|
out: |
|
raw_spin_unlock(&pwq->pool->lock); |
|
rcu_read_unlock(); |
|
} |
|
|
|
/** |
|
* queue_work_on - queue work on specific cpu |
|
* @cpu: CPU number to execute work on |
|
* @wq: workqueue to use |
|
* @work: work to queue |
|
* |
|
* We queue the work to a specific CPU, the caller must ensure it |
|
* can't go away. |
|
* |
|
* Return: %false if @work was already on a queue, %true otherwise. |
|
*/ |
|
bool queue_work_on(int cpu, struct workqueue_struct *wq, |
|
struct work_struct *work) |
|
{ |
|
bool ret = false; |
|
unsigned long flags; |
|
|
|
local_irq_save(flags); |
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
|
__queue_work(cpu, wq, work); |
|
ret = true; |
|
} |
|
|
|
local_irq_restore(flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(queue_work_on); |
|
|
|
/** |
|
* workqueue_select_cpu_near - Select a CPU based on NUMA node |
|
* @node: NUMA node ID that we want to select a CPU from |
|
* |
|
* This function will attempt to find a "random" cpu available on a given |
|
* node. If there are no CPUs available on the given node it will return |
|
* WORK_CPU_UNBOUND indicating that we should just schedule to any |
|
* available CPU if we need to schedule this work. |
|
*/ |
|
static int workqueue_select_cpu_near(int node) |
|
{ |
|
int cpu; |
|
|
|
/* No point in doing this if NUMA isn't enabled for workqueues */ |
|
if (!wq_numa_enabled) |
|
return WORK_CPU_UNBOUND; |
|
|
|
/* Delay binding to CPU if node is not valid or online */ |
|
if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) |
|
return WORK_CPU_UNBOUND; |
|
|
|
/* Use local node/cpu if we are already there */ |
|
cpu = raw_smp_processor_id(); |
|
if (node == cpu_to_node(cpu)) |
|
return cpu; |
|
|
|
/* Use "random" otherwise know as "first" online CPU of node */ |
|
cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); |
|
|
|
/* If CPU is valid return that, otherwise just defer */ |
|
return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; |
|
} |
|
|
|
/** |
|
* queue_work_node - queue work on a "random" cpu for a given NUMA node |
|
* @node: NUMA node that we are targeting the work for |
|
* @wq: workqueue to use |
|
* @work: work to queue |
|
* |
|
* We queue the work to a "random" CPU within a given NUMA node. The basic |
|
* idea here is to provide a way to somehow associate work with a given |
|
* NUMA node. |
|
* |
|
* This function will only make a best effort attempt at getting this onto |
|
* the right NUMA node. If no node is requested or the requested node is |
|
* offline then we just fall back to standard queue_work behavior. |
|
* |
|
* Currently the "random" CPU ends up being the first available CPU in the |
|
* intersection of cpu_online_mask and the cpumask of the node, unless we |
|
* are running on the node. In that case we just use the current CPU. |
|
* |
|
* Return: %false if @work was already on a queue, %true otherwise. |
|
*/ |
|
bool queue_work_node(int node, struct workqueue_struct *wq, |
|
struct work_struct *work) |
|
{ |
|
unsigned long flags; |
|
bool ret = false; |
|
|
|
/* |
|
* This current implementation is specific to unbound workqueues. |
|
* Specifically we only return the first available CPU for a given |
|
* node instead of cycling through individual CPUs within the node. |
|
* |
|
* If this is used with a per-cpu workqueue then the logic in |
|
* workqueue_select_cpu_near would need to be updated to allow for |
|
* some round robin type logic. |
|
*/ |
|
WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); |
|
|
|
local_irq_save(flags); |
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
|
int cpu = workqueue_select_cpu_near(node); |
|
|
|
__queue_work(cpu, wq, work); |
|
ret = true; |
|
} |
|
|
|
local_irq_restore(flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(queue_work_node); |
|
|
|
void delayed_work_timer_fn(struct timer_list *t) |
|
{ |
|
struct delayed_work *dwork = from_timer(dwork, t, timer); |
|
|
|
/* should have been called from irqsafe timer with irq already off */ |
|
__queue_work(dwork->cpu, dwork->wq, &dwork->work); |
|
} |
|
EXPORT_SYMBOL(delayed_work_timer_fn); |
|
|
|
static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
|
struct delayed_work *dwork, unsigned long delay) |
|
{ |
|
struct timer_list *timer = &dwork->timer; |
|
struct work_struct *work = &dwork->work; |
|
|
|
WARN_ON_ONCE(!wq); |
|
WARN_ON_FUNCTION_MISMATCH(timer->function, delayed_work_timer_fn); |
|
WARN_ON_ONCE(timer_pending(timer)); |
|
WARN_ON_ONCE(!list_empty(&work->entry)); |
|
|
|
/* |
|
* If @delay is 0, queue @dwork->work immediately. This is for |
|
* both optimization and correctness. The earliest @timer can |
|
* expire is on the closest next tick and delayed_work users depend |
|
* on that there's no such delay when @delay is 0. |
|
*/ |
|
if (!delay) { |
|
__queue_work(cpu, wq, &dwork->work); |
|
return; |
|
} |
|
|
|
dwork->wq = wq; |
|
dwork->cpu = cpu; |
|
timer->expires = jiffies + delay; |
|
|
|
if (unlikely(cpu != WORK_CPU_UNBOUND)) |
|
add_timer_on(timer, cpu); |
|
else |
|
add_timer(timer); |
|
} |
|
|
|
/** |
|
* queue_delayed_work_on - queue work on specific CPU after delay |
|
* @cpu: CPU number to execute work on |
|
* @wq: workqueue to use |
|
* @dwork: work to queue |
|
* @delay: number of jiffies to wait before queueing |
|
* |
|
* Return: %false if @work was already on a queue, %true otherwise. If |
|
* @delay is zero and @dwork is idle, it will be scheduled for immediate |
|
* execution. |
|
*/ |
|
bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
|
struct delayed_work *dwork, unsigned long delay) |
|
{ |
|
struct work_struct *work = &dwork->work; |
|
bool ret = false; |
|
unsigned long flags; |
|
|
|
/* read the comment in __queue_work() */ |
|
local_irq_save(flags); |
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
|
__queue_delayed_work(cpu, wq, dwork, delay); |
|
ret = true; |
|
} |
|
|
|
local_irq_restore(flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(queue_delayed_work_on); |
|
|
|
/** |
|
* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU |
|
* @cpu: CPU number to execute work on |
|
* @wq: workqueue to use |
|
* @dwork: work to queue |
|
* @delay: number of jiffies to wait before queueing |
|
* |
|
* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, |
|
* modify @dwork's timer so that it expires after @delay. If @delay is |
|
* zero, @work is guaranteed to be scheduled immediately regardless of its |
|
* current state. |
|
* |
|
* Return: %false if @dwork was idle and queued, %true if @dwork was |
|
* pending and its timer was modified. |
|
* |
|
* This function is safe to call from any context including IRQ handler. |
|
* See try_to_grab_pending() for details. |
|
*/ |
|
bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
|
struct delayed_work *dwork, unsigned long delay) |
|
{ |
|
unsigned long flags; |
|
int ret; |
|
|
|
do { |
|
ret = try_to_grab_pending(&dwork->work, true, &flags); |
|
} while (unlikely(ret == -EAGAIN)); |
|
|
|
if (likely(ret >= 0)) { |
|
__queue_delayed_work(cpu, wq, dwork, delay); |
|
local_irq_restore(flags); |
|
} |
|
|
|
/* -ENOENT from try_to_grab_pending() becomes %true */ |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
|
|
|
static void rcu_work_rcufn(struct rcu_head *rcu) |
|
{ |
|
struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); |
|
|
|
/* read the comment in __queue_work() */ |
|
local_irq_disable(); |
|
__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); |
|
local_irq_enable(); |
|
} |
|
|
|
/** |
|
* queue_rcu_work - queue work after a RCU grace period |
|
* @wq: workqueue to use |
|
* @rwork: work to queue |
|
* |
|
* Return: %false if @rwork was already pending, %true otherwise. Note |
|
* that a full RCU grace period is guaranteed only after a %true return. |
|
* While @rwork is guaranteed to be executed after a %false return, the |
|
* execution may happen before a full RCU grace period has passed. |
|
*/ |
|
bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) |
|
{ |
|
struct work_struct *work = &rwork->work; |
|
|
|
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
|
rwork->wq = wq; |
|
call_rcu(&rwork->rcu, rcu_work_rcufn); |
|
return true; |
|
} |
|
|
|
return false; |
|
} |
|
EXPORT_SYMBOL(queue_rcu_work); |
|
|
|
/** |
|
* worker_enter_idle - enter idle state |
|
* @worker: worker which is entering idle state |
|
* |
|
* @worker is entering idle state. Update stats and idle timer if |
|
* necessary. |
|
* |
|
* LOCKING: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void worker_enter_idle(struct worker *worker) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
|
|
if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || |
|
WARN_ON_ONCE(!list_empty(&worker->entry) && |
|
(worker->hentry.next || worker->hentry.pprev))) |
|
return; |
|
|
|
/* can't use worker_set_flags(), also called from create_worker() */ |
|
worker->flags |= WORKER_IDLE; |
|
pool->nr_idle++; |
|
worker->last_active = jiffies; |
|
|
|
/* idle_list is LIFO */ |
|
list_add(&worker->entry, &pool->idle_list); |
|
|
|
if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
|
mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); |
|
|
|
/* |
|
* Sanity check nr_running. Because unbind_workers() releases |
|
* pool->lock between setting %WORKER_UNBOUND and zapping |
|
* nr_running, the warning may trigger spuriously. Check iff |
|
* unbind is not in progress. |
|
*/ |
|
WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
|
pool->nr_workers == pool->nr_idle && |
|
atomic_read(&pool->nr_running)); |
|
} |
|
|
|
/** |
|
* worker_leave_idle - leave idle state |
|
* @worker: worker which is leaving idle state |
|
* |
|
* @worker is leaving idle state. Update stats. |
|
* |
|
* LOCKING: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void worker_leave_idle(struct worker *worker) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
|
|
if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) |
|
return; |
|
worker_clr_flags(worker, WORKER_IDLE); |
|
pool->nr_idle--; |
|
list_del_init(&worker->entry); |
|
} |
|
|
|
static struct worker *alloc_worker(int node) |
|
{ |
|
struct worker *worker; |
|
|
|
worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); |
|
if (worker) { |
|
INIT_LIST_HEAD(&worker->entry); |
|
INIT_LIST_HEAD(&worker->scheduled); |
|
INIT_LIST_HEAD(&worker->node); |
|
/* on creation a worker is in !idle && prep state */ |
|
worker->flags = WORKER_PREP; |
|
} |
|
return worker; |
|
} |
|
|
|
/** |
|
* worker_attach_to_pool() - attach a worker to a pool |
|
* @worker: worker to be attached |
|
* @pool: the target pool |
|
* |
|
* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and |
|
* cpu-binding of @worker are kept coordinated with the pool across |
|
* cpu-[un]hotplugs. |
|
*/ |
|
static void worker_attach_to_pool(struct worker *worker, |
|
struct worker_pool *pool) |
|
{ |
|
mutex_lock(&wq_pool_attach_mutex); |
|
|
|
/* |
|
* The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains |
|
* stable across this function. See the comments above the flag |
|
* definition for details. |
|
*/ |
|
if (pool->flags & POOL_DISASSOCIATED) |
|
worker->flags |= WORKER_UNBOUND; |
|
else |
|
kthread_set_per_cpu(worker->task, pool->cpu); |
|
|
|
if (worker->rescue_wq) |
|
set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); |
|
|
|
list_add_tail(&worker->node, &pool->workers); |
|
worker->pool = pool; |
|
|
|
mutex_unlock(&wq_pool_attach_mutex); |
|
} |
|
|
|
/** |
|
* worker_detach_from_pool() - detach a worker from its pool |
|
* @worker: worker which is attached to its pool |
|
* |
|
* Undo the attaching which had been done in worker_attach_to_pool(). The |
|
* caller worker shouldn't access to the pool after detached except it has |
|
* other reference to the pool. |
|
*/ |
|
static void worker_detach_from_pool(struct worker *worker) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
struct completion *detach_completion = NULL; |
|
|
|
mutex_lock(&wq_pool_attach_mutex); |
|
|
|
kthread_set_per_cpu(worker->task, -1); |
|
list_del(&worker->node); |
|
worker->pool = NULL; |
|
|
|
if (list_empty(&pool->workers)) |
|
detach_completion = pool->detach_completion; |
|
mutex_unlock(&wq_pool_attach_mutex); |
|
|
|
/* clear leftover flags without pool->lock after it is detached */ |
|
worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); |
|
|
|
if (detach_completion) |
|
complete(detach_completion); |
|
} |
|
|
|
/** |
|
* create_worker - create a new workqueue worker |
|
* @pool: pool the new worker will belong to |
|
* |
|
* Create and start a new worker which is attached to @pool. |
|
* |
|
* CONTEXT: |
|
* Might sleep. Does GFP_KERNEL allocations. |
|
* |
|
* Return: |
|
* Pointer to the newly created worker. |
|
*/ |
|
static struct worker *create_worker(struct worker_pool *pool) |
|
{ |
|
struct worker *worker; |
|
int id; |
|
char id_buf[16]; |
|
|
|
/* ID is needed to determine kthread name */ |
|
id = ida_alloc(&pool->worker_ida, GFP_KERNEL); |
|
if (id < 0) |
|
return NULL; |
|
|
|
worker = alloc_worker(pool->node); |
|
if (!worker) |
|
goto fail; |
|
|
|
worker->id = id; |
|
|
|
if (pool->cpu >= 0) |
|
snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, |
|
pool->attrs->nice < 0 ? "H" : ""); |
|
else |
|
snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); |
|
|
|
worker->task = kthread_create_on_node(worker_thread, worker, pool->node, |
|
"kworker/%s", id_buf); |
|
if (IS_ERR(worker->task)) |
|
goto fail; |
|
|
|
set_user_nice(worker->task, pool->attrs->nice); |
|
kthread_bind_mask(worker->task, pool->attrs->cpumask); |
|
|
|
/* successful, attach the worker to the pool */ |
|
worker_attach_to_pool(worker, pool); |
|
|
|
/* start the newly created worker */ |
|
raw_spin_lock_irq(&pool->lock); |
|
worker->pool->nr_workers++; |
|
worker_enter_idle(worker); |
|
wake_up_process(worker->task); |
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
return worker; |
|
|
|
fail: |
|
ida_free(&pool->worker_ida, id); |
|
kfree(worker); |
|
return NULL; |
|
} |
|
|
|
/** |
|
* destroy_worker - destroy a workqueue worker |
|
* @worker: worker to be destroyed |
|
* |
|
* Destroy @worker and adjust @pool stats accordingly. The worker should |
|
* be idle. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void destroy_worker(struct worker *worker) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
|
|
lockdep_assert_held(&pool->lock); |
|
|
|
/* sanity check frenzy */ |
|
if (WARN_ON(worker->current_work) || |
|
WARN_ON(!list_empty(&worker->scheduled)) || |
|
WARN_ON(!(worker->flags & WORKER_IDLE))) |
|
return; |
|
|
|
pool->nr_workers--; |
|
pool->nr_idle--; |
|
|
|
list_del_init(&worker->entry); |
|
worker->flags |= WORKER_DIE; |
|
wake_up_process(worker->task); |
|
} |
|
|
|
static void idle_worker_timeout(struct timer_list *t) |
|
{ |
|
struct worker_pool *pool = from_timer(pool, t, idle_timer); |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
while (too_many_workers(pool)) { |
|
struct worker *worker; |
|
unsigned long expires; |
|
|
|
/* idle_list is kept in LIFO order, check the last one */ |
|
worker = list_entry(pool->idle_list.prev, struct worker, entry); |
|
expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
|
|
|
if (time_before(jiffies, expires)) { |
|
mod_timer(&pool->idle_timer, expires); |
|
break; |
|
} |
|
|
|
destroy_worker(worker); |
|
} |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
|
|
static void send_mayday(struct work_struct *work) |
|
{ |
|
struct pool_workqueue *pwq = get_work_pwq(work); |
|
struct workqueue_struct *wq = pwq->wq; |
|
|
|
lockdep_assert_held(&wq_mayday_lock); |
|
|
|
if (!wq->rescuer) |
|
return; |
|
|
|
/* mayday mayday mayday */ |
|
if (list_empty(&pwq->mayday_node)) { |
|
/* |
|
* If @pwq is for an unbound wq, its base ref may be put at |
|
* any time due to an attribute change. Pin @pwq until the |
|
* rescuer is done with it. |
|
*/ |
|
get_pwq(pwq); |
|
list_add_tail(&pwq->mayday_node, &wq->maydays); |
|
wake_up_process(wq->rescuer->task); |
|
} |
|
} |
|
|
|
static void pool_mayday_timeout(struct timer_list *t) |
|
{ |
|
struct worker_pool *pool = from_timer(pool, t, mayday_timer); |
|
struct work_struct *work; |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ |
|
|
|
if (need_to_create_worker(pool)) { |
|
/* |
|
* We've been trying to create a new worker but |
|
* haven't been successful. We might be hitting an |
|
* allocation deadlock. Send distress signals to |
|
* rescuers. |
|
*/ |
|
list_for_each_entry(work, &pool->worklist, entry) |
|
send_mayday(work); |
|
} |
|
|
|
raw_spin_unlock(&wq_mayday_lock); |
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
|
} |
|
|
|
/** |
|
* maybe_create_worker - create a new worker if necessary |
|
* @pool: pool to create a new worker for |
|
* |
|
* Create a new worker for @pool if necessary. @pool is guaranteed to |
|
* have at least one idle worker on return from this function. If |
|
* creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
|
* sent to all rescuers with works scheduled on @pool to resolve |
|
* possible allocation deadlock. |
|
* |
|
* On return, need_to_create_worker() is guaranteed to be %false and |
|
* may_start_working() %true. |
|
* |
|
* LOCKING: |
|
* raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
|
* multiple times. Does GFP_KERNEL allocations. Called only from |
|
* manager. |
|
*/ |
|
static void maybe_create_worker(struct worker_pool *pool) |
|
__releases(&pool->lock) |
|
__acquires(&pool->lock) |
|
{ |
|
restart: |
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
|
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
|
|
|
while (true) { |
|
if (create_worker(pool) || !need_to_create_worker(pool)) |
|
break; |
|
|
|
schedule_timeout_interruptible(CREATE_COOLDOWN); |
|
|
|
if (!need_to_create_worker(pool)) |
|
break; |
|
} |
|
|
|
del_timer_sync(&pool->mayday_timer); |
|
raw_spin_lock_irq(&pool->lock); |
|
/* |
|
* This is necessary even after a new worker was just successfully |
|
* created as @pool->lock was dropped and the new worker might have |
|
* already become busy. |
|
*/ |
|
if (need_to_create_worker(pool)) |
|
goto restart; |
|
} |
|
|
|
/** |
|
* manage_workers - manage worker pool |
|
* @worker: self |
|
* |
|
* Assume the manager role and manage the worker pool @worker belongs |
|
* to. At any given time, there can be only zero or one manager per |
|
* pool. The exclusion is handled automatically by this function. |
|
* |
|
* The caller can safely start processing works on false return. On |
|
* true return, it's guaranteed that need_to_create_worker() is false |
|
* and may_start_working() is true. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
|
* multiple times. Does GFP_KERNEL allocations. |
|
* |
|
* Return: |
|
* %false if the pool doesn't need management and the caller can safely |
|
* start processing works, %true if management function was performed and |
|
* the conditions that the caller verified before calling the function may |
|
* no longer be true. |
|
*/ |
|
static bool manage_workers(struct worker *worker) |
|
{ |
|
struct worker_pool *pool = worker->pool; |
|
|
|
if (pool->flags & POOL_MANAGER_ACTIVE) |
|
return false; |
|
|
|
pool->flags |= POOL_MANAGER_ACTIVE; |
|
pool->manager = worker; |
|
|
|
maybe_create_worker(pool); |
|
|
|
pool->manager = NULL; |
|
pool->flags &= ~POOL_MANAGER_ACTIVE; |
|
rcuwait_wake_up(&manager_wait); |
|
return true; |
|
} |
|
|
|
/** |
|
* process_one_work - process single work |
|
* @worker: self |
|
* @work: work to process |
|
* |
|
* Process @work. This function contains all the logics necessary to |
|
* process a single work including synchronization against and |
|
* interaction with other workers on the same cpu, queueing and |
|
* flushing. As long as context requirement is met, any worker can |
|
* call this function to process a work. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock) which is released and regrabbed. |
|
*/ |
|
static void process_one_work(struct worker *worker, struct work_struct *work) |
|
__releases(&pool->lock) |
|
__acquires(&pool->lock) |
|
{ |
|
struct pool_workqueue *pwq = get_work_pwq(work); |
|
struct worker_pool *pool = worker->pool; |
|
bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; |
|
unsigned long work_data; |
|
struct worker *collision; |
|
#ifdef CONFIG_LOCKDEP |
|
/* |
|
* It is permissible to free the struct work_struct from |
|
* inside the function that is called from it, this we need to |
|
* take into account for lockdep too. To avoid bogus "held |
|
* lock freed" warnings as well as problems when looking into |
|
* work->lockdep_map, make a copy and use that here. |
|
*/ |
|
struct lockdep_map lockdep_map; |
|
|
|
lockdep_copy_map(&lockdep_map, &work->lockdep_map); |
|
#endif |
|
/* ensure we're on the correct CPU */ |
|
WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
|
raw_smp_processor_id() != pool->cpu); |
|
|
|
/* |
|
* A single work shouldn't be executed concurrently by |
|
* multiple workers on a single cpu. Check whether anyone is |
|
* already processing the work. If so, defer the work to the |
|
* currently executing one. |
|
*/ |
|
collision = find_worker_executing_work(pool, work); |
|
if (unlikely(collision)) { |
|
move_linked_works(work, &collision->scheduled, NULL); |
|
return; |
|
} |
|
|
|
/* claim and dequeue */ |
|
debug_work_deactivate(work); |
|
hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
|
worker->current_work = work; |
|
worker->current_func = work->func; |
|
worker->current_pwq = pwq; |
|
work_data = *work_data_bits(work); |
|
worker->current_color = get_work_color(work_data); |
|
|
|
/* |
|
* Record wq name for cmdline and debug reporting, may get |
|
* overridden through set_worker_desc(). |
|
*/ |
|
strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); |
|
|
|
list_del_init(&work->entry); |
|
|
|
/* |
|
* CPU intensive works don't participate in concurrency management. |
|
* They're the scheduler's responsibility. This takes @worker out |
|
* of concurrency management and the next code block will chain |
|
* execution of the pending work items. |
|
*/ |
|
if (unlikely(cpu_intensive)) |
|
worker_set_flags(worker, WORKER_CPU_INTENSIVE); |
|
|
|
/* |
|
* Wake up another worker if necessary. The condition is always |
|
* false for normal per-cpu workers since nr_running would always |
|
* be >= 1 at this point. This is used to chain execution of the |
|
* pending work items for WORKER_NOT_RUNNING workers such as the |
|
* UNBOUND and CPU_INTENSIVE ones. |
|
*/ |
|
if (need_more_worker(pool)) |
|
wake_up_worker(pool); |
|
|
|
/* |
|
* Record the last pool and clear PENDING which should be the last |
|
* update to @work. Also, do this inside @pool->lock so that |
|
* PENDING and queued state changes happen together while IRQ is |
|
* disabled. |
|
*/ |
|
set_work_pool_and_clear_pending(work, pool->id); |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
lock_map_acquire(&pwq->wq->lockdep_map); |
|
lock_map_acquire(&lockdep_map); |
|
/* |
|
* Strictly speaking we should mark the invariant state without holding |
|
* any locks, that is, before these two lock_map_acquire()'s. |
|
* |
|
* However, that would result in: |
|
* |
|
* A(W1) |
|
* WFC(C) |
|
* A(W1) |
|
* C(C) |
|
* |
|
* Which would create W1->C->W1 dependencies, even though there is no |
|
* actual deadlock possible. There are two solutions, using a |
|
* read-recursive acquire on the work(queue) 'locks', but this will then |
|
* hit the lockdep limitation on recursive locks, or simply discard |
|
* these locks. |
|
* |
|
* AFAICT there is no possible deadlock scenario between the |
|
* flush_work() and complete() primitives (except for single-threaded |
|
* workqueues), so hiding them isn't a problem. |
|
*/ |
|
lockdep_invariant_state(true); |
|
trace_workqueue_execute_start(work); |
|
worker->current_func(work); |
|
/* |
|
* While we must be careful to not use "work" after this, the trace |
|
* point will only record its address. |
|
*/ |
|
trace_workqueue_execute_end(work, worker->current_func); |
|
lock_map_release(&lockdep_map); |
|
lock_map_release(&pwq->wq->lockdep_map); |
|
|
|
if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
|
pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
|
" last function: %ps\n", |
|
current->comm, preempt_count(), task_pid_nr(current), |
|
worker->current_func); |
|
debug_show_held_locks(current); |
|
dump_stack(); |
|
} |
|
|
|
/* |
|
* The following prevents a kworker from hogging CPU on !PREEMPTION |
|
* kernels, where a requeueing work item waiting for something to |
|
* happen could deadlock with stop_machine as such work item could |
|
* indefinitely requeue itself while all other CPUs are trapped in |
|
* stop_machine. At the same time, report a quiescent RCU state so |
|
* the same condition doesn't freeze RCU. |
|
*/ |
|
cond_resched(); |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
/* clear cpu intensive status */ |
|
if (unlikely(cpu_intensive)) |
|
worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
|
|
|
/* tag the worker for identification in schedule() */ |
|
worker->last_func = worker->current_func; |
|
|
|
/* we're done with it, release */ |
|
hash_del(&worker->hentry); |
|
worker->current_work = NULL; |
|
worker->current_func = NULL; |
|
worker->current_pwq = NULL; |
|
worker->current_color = INT_MAX; |
|
pwq_dec_nr_in_flight(pwq, work_data); |
|
} |
|
|
|
/** |
|
* process_scheduled_works - process scheduled works |
|
* @worker: self |
|
* |
|
* Process all scheduled works. Please note that the scheduled list |
|
* may change while processing a work, so this function repeatedly |
|
* fetches a work from the top and executes it. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock) which may be released and regrabbed |
|
* multiple times. |
|
*/ |
|
static void process_scheduled_works(struct worker *worker) |
|
{ |
|
while (!list_empty(&worker->scheduled)) { |
|
struct work_struct *work = list_first_entry(&worker->scheduled, |
|
struct work_struct, entry); |
|
process_one_work(worker, work); |
|
} |
|
} |
|
|
|
static void set_pf_worker(bool val) |
|
{ |
|
mutex_lock(&wq_pool_attach_mutex); |
|
if (val) |
|
current->flags |= PF_WQ_WORKER; |
|
else |
|
current->flags &= ~PF_WQ_WORKER; |
|
mutex_unlock(&wq_pool_attach_mutex); |
|
} |
|
|
|
/** |
|
* worker_thread - the worker thread function |
|
* @__worker: self |
|
* |
|
* The worker thread function. All workers belong to a worker_pool - |
|
* either a per-cpu one or dynamic unbound one. These workers process all |
|
* work items regardless of their specific target workqueue. The only |
|
* exception is work items which belong to workqueues with a rescuer which |
|
* will be explained in rescuer_thread(). |
|
* |
|
* Return: 0 |
|
*/ |
|
static int worker_thread(void *__worker) |
|
{ |
|
struct worker *worker = __worker; |
|
struct worker_pool *pool = worker->pool; |
|
|
|
/* tell the scheduler that this is a workqueue worker */ |
|
set_pf_worker(true); |
|
woke_up: |
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
/* am I supposed to die? */ |
|
if (unlikely(worker->flags & WORKER_DIE)) { |
|
raw_spin_unlock_irq(&pool->lock); |
|
WARN_ON_ONCE(!list_empty(&worker->entry)); |
|
set_pf_worker(false); |
|
|
|
set_task_comm(worker->task, "kworker/dying"); |
|
ida_free(&pool->worker_ida, worker->id); |
|
worker_detach_from_pool(worker); |
|
kfree(worker); |
|
return 0; |
|
} |
|
|
|
worker_leave_idle(worker); |
|
recheck: |
|
/* no more worker necessary? */ |
|
if (!need_more_worker(pool)) |
|
goto sleep; |
|
|
|
/* do we need to manage? */ |
|
if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
|
goto recheck; |
|
|
|
/* |
|
* ->scheduled list can only be filled while a worker is |
|
* preparing to process a work or actually processing it. |
|
* Make sure nobody diddled with it while I was sleeping. |
|
*/ |
|
WARN_ON_ONCE(!list_empty(&worker->scheduled)); |
|
|
|
/* |
|
* Finish PREP stage. We're guaranteed to have at least one idle |
|
* worker or that someone else has already assumed the manager |
|
* role. This is where @worker starts participating in concurrency |
|
* management if applicable and concurrency management is restored |
|
* after being rebound. See rebind_workers() for details. |
|
*/ |
|
worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); |
|
|
|
do { |
|
struct work_struct *work = |
|
list_first_entry(&pool->worklist, |
|
struct work_struct, entry); |
|
|
|
pool->watchdog_ts = jiffies; |
|
|
|
if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
|
/* optimization path, not strictly necessary */ |
|
process_one_work(worker, work); |
|
if (unlikely(!list_empty(&worker->scheduled))) |
|
process_scheduled_works(worker); |
|
} else { |
|
move_linked_works(work, &worker->scheduled, NULL); |
|
process_scheduled_works(worker); |
|
} |
|
} while (keep_working(pool)); |
|
|
|
worker_set_flags(worker, WORKER_PREP); |
|
sleep: |
|
/* |
|
* pool->lock is held and there's no work to process and no need to |
|
* manage, sleep. Workers are woken up only while holding |
|
* pool->lock or from local cpu, so setting the current state |
|
* before releasing pool->lock is enough to prevent losing any |
|
* event. |
|
*/ |
|
worker_enter_idle(worker); |
|
__set_current_state(TASK_IDLE); |
|
raw_spin_unlock_irq(&pool->lock); |
|
schedule(); |
|
goto woke_up; |
|
} |
|
|
|
/** |
|
* rescuer_thread - the rescuer thread function |
|
* @__rescuer: self |
|
* |
|
* Workqueue rescuer thread function. There's one rescuer for each |
|
* workqueue which has WQ_MEM_RECLAIM set. |
|
* |
|
* Regular work processing on a pool may block trying to create a new |
|
* worker which uses GFP_KERNEL allocation which has slight chance of |
|
* developing into deadlock if some works currently on the same queue |
|
* need to be processed to satisfy the GFP_KERNEL allocation. This is |
|
* the problem rescuer solves. |
|
* |
|
* When such condition is possible, the pool summons rescuers of all |
|
* workqueues which have works queued on the pool and let them process |
|
* those works so that forward progress can be guaranteed. |
|
* |
|
* This should happen rarely. |
|
* |
|
* Return: 0 |
|
*/ |
|
static int rescuer_thread(void *__rescuer) |
|
{ |
|
struct worker *rescuer = __rescuer; |
|
struct workqueue_struct *wq = rescuer->rescue_wq; |
|
struct list_head *scheduled = &rescuer->scheduled; |
|
bool should_stop; |
|
|
|
set_user_nice(current, RESCUER_NICE_LEVEL); |
|
|
|
/* |
|
* Mark rescuer as worker too. As WORKER_PREP is never cleared, it |
|
* doesn't participate in concurrency management. |
|
*/ |
|
set_pf_worker(true); |
|
repeat: |
|
set_current_state(TASK_IDLE); |
|
|
|
/* |
|
* By the time the rescuer is requested to stop, the workqueue |
|
* shouldn't have any work pending, but @wq->maydays may still have |
|
* pwq(s) queued. This can happen by non-rescuer workers consuming |
|
* all the work items before the rescuer got to them. Go through |
|
* @wq->maydays processing before acting on should_stop so that the |
|
* list is always empty on exit. |
|
*/ |
|
should_stop = kthread_should_stop(); |
|
|
|
/* see whether any pwq is asking for help */ |
|
raw_spin_lock_irq(&wq_mayday_lock); |
|
|
|
while (!list_empty(&wq->maydays)) { |
|
struct pool_workqueue *pwq = list_first_entry(&wq->maydays, |
|
struct pool_workqueue, mayday_node); |
|
struct worker_pool *pool = pwq->pool; |
|
struct work_struct *work, *n; |
|
bool first = true; |
|
|
|
__set_current_state(TASK_RUNNING); |
|
list_del_init(&pwq->mayday_node); |
|
|
|
raw_spin_unlock_irq(&wq_mayday_lock); |
|
|
|
worker_attach_to_pool(rescuer, pool); |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
/* |
|
* Slurp in all works issued via this workqueue and |
|
* process'em. |
|
*/ |
|
WARN_ON_ONCE(!list_empty(scheduled)); |
|
list_for_each_entry_safe(work, n, &pool->worklist, entry) { |
|
if (get_work_pwq(work) == pwq) { |
|
if (first) |
|
pool->watchdog_ts = jiffies; |
|
move_linked_works(work, scheduled, &n); |
|
} |
|
first = false; |
|
} |
|
|
|
if (!list_empty(scheduled)) { |
|
process_scheduled_works(rescuer); |
|
|
|
/* |
|
* The above execution of rescued work items could |
|
* have created more to rescue through |
|
* pwq_activate_first_inactive() or chained |
|
* queueing. Let's put @pwq back on mayday list so |
|
* that such back-to-back work items, which may be |
|
* being used to relieve memory pressure, don't |
|
* incur MAYDAY_INTERVAL delay inbetween. |
|
*/ |
|
if (pwq->nr_active && need_to_create_worker(pool)) { |
|
raw_spin_lock(&wq_mayday_lock); |
|
/* |
|
* Queue iff we aren't racing destruction |
|
* and somebody else hasn't queued it already. |
|
*/ |
|
if (wq->rescuer && list_empty(&pwq->mayday_node)) { |
|
get_pwq(pwq); |
|
list_add_tail(&pwq->mayday_node, &wq->maydays); |
|
} |
|
raw_spin_unlock(&wq_mayday_lock); |
|
} |
|
} |
|
|
|
/* |
|
* Put the reference grabbed by send_mayday(). @pool won't |
|
* go away while we're still attached to it. |
|
*/ |
|
put_pwq(pwq); |
|
|
|
/* |
|
* Leave this pool. If need_more_worker() is %true, notify a |
|
* regular worker; otherwise, we end up with 0 concurrency |
|
* and stalling the execution. |
|
*/ |
|
if (need_more_worker(pool)) |
|
wake_up_worker(pool); |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
worker_detach_from_pool(rescuer); |
|
|
|
raw_spin_lock_irq(&wq_mayday_lock); |
|
} |
|
|
|
raw_spin_unlock_irq(&wq_mayday_lock); |
|
|
|
if (should_stop) { |
|
__set_current_state(TASK_RUNNING); |
|
set_pf_worker(false); |
|
return 0; |
|
} |
|
|
|
/* rescuers should never participate in concurrency management */ |
|
WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); |
|
schedule(); |
|
goto repeat; |
|
} |
|
|
|
/** |
|
* check_flush_dependency - check for flush dependency sanity |
|
* @target_wq: workqueue being flushed |
|
* @target_work: work item being flushed (NULL for workqueue flushes) |
|
* |
|
* %current is trying to flush the whole @target_wq or @target_work on it. |
|
* If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not |
|
* reclaiming memory or running on a workqueue which doesn't have |
|
* %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to |
|
* a deadlock. |
|
*/ |
|
static void check_flush_dependency(struct workqueue_struct *target_wq, |
|
struct work_struct *target_work) |
|
{ |
|
work_func_t target_func = target_work ? target_work->func : NULL; |
|
struct worker *worker; |
|
|
|
if (target_wq->flags & WQ_MEM_RECLAIM) |
|
return; |
|
|
|
worker = current_wq_worker(); |
|
|
|
WARN_ONCE(current->flags & PF_MEMALLOC, |
|
"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", |
|
current->pid, current->comm, target_wq->name, target_func); |
|
WARN_ONCE(worker && ((worker->current_pwq->wq->flags & |
|
(WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), |
|
"workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", |
|
worker->current_pwq->wq->name, worker->current_func, |
|
target_wq->name, target_func); |
|
} |
|
|
|
struct wq_barrier { |
|
struct work_struct work; |
|
struct completion done; |
|
struct task_struct *task; /* purely informational */ |
|
}; |
|
|
|
static void wq_barrier_func(struct work_struct *work) |
|
{ |
|
struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
|
complete(&barr->done); |
|
} |
|
|
|
/** |
|
* insert_wq_barrier - insert a barrier work |
|
* @pwq: pwq to insert barrier into |
|
* @barr: wq_barrier to insert |
|
* @target: target work to attach @barr to |
|
* @worker: worker currently executing @target, NULL if @target is not executing |
|
* |
|
* @barr is linked to @target such that @barr is completed only after |
|
* @target finishes execution. Please note that the ordering |
|
* guarantee is observed only with respect to @target and on the local |
|
* cpu. |
|
* |
|
* Currently, a queued barrier can't be canceled. This is because |
|
* try_to_grab_pending() can't determine whether the work to be |
|
* grabbed is at the head of the queue and thus can't clear LINKED |
|
* flag of the previous work while there must be a valid next work |
|
* after a work with LINKED flag set. |
|
* |
|
* Note that when @worker is non-NULL, @target may be modified |
|
* underneath us, so we can't reliably determine pwq from @target. |
|
* |
|
* CONTEXT: |
|
* raw_spin_lock_irq(pool->lock). |
|
*/ |
|
static void insert_wq_barrier(struct pool_workqueue *pwq, |
|
struct wq_barrier *barr, |
|
struct work_struct *target, struct worker *worker) |
|
{ |
|
unsigned int work_flags = 0; |
|
unsigned int work_color; |
|
struct list_head *head; |
|
|
|
/* |
|
* debugobject calls are safe here even with pool->lock locked |
|
* as we know for sure that this will not trigger any of the |
|
* checks and call back into the fixup functions where we |
|
* might deadlock. |
|
*/ |
|
INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
|
__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
|
|
|
init_completion_map(&barr->done, &target->lockdep_map); |
|
|
|
barr->task = current; |
|
|
|
/* The barrier work item does not participate in pwq->nr_active. */ |
|
work_flags |= WORK_STRUCT_INACTIVE; |
|
|
|
/* |
|
* If @target is currently being executed, schedule the |
|
* barrier to the worker; otherwise, put it after @target. |
|
*/ |
|
if (worker) { |
|
head = worker->scheduled.next; |
|
work_color = worker->current_color; |
|
} else { |
|
unsigned long *bits = work_data_bits(target); |
|
|
|
head = target->entry.next; |
|
/* there can already be other linked works, inherit and set */ |
|
work_flags |= *bits & WORK_STRUCT_LINKED; |
|
work_color = get_work_color(*bits); |
|
__set_bit(WORK_STRUCT_LINKED_BIT, bits); |
|
} |
|
|
|
pwq->nr_in_flight[work_color]++; |
|
work_flags |= work_color_to_flags(work_color); |
|
|
|
debug_work_activate(&barr->work); |
|
insert_work(pwq, &barr->work, head, work_flags); |
|
} |
|
|
|
/** |
|
* flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
|
* @wq: workqueue being flushed |
|
* @flush_color: new flush color, < 0 for no-op |
|
* @work_color: new work color, < 0 for no-op |
|
* |
|
* Prepare pwqs for workqueue flushing. |
|
* |
|
* If @flush_color is non-negative, flush_color on all pwqs should be |
|
* -1. If no pwq has in-flight commands at the specified color, all |
|
* pwq->flush_color's stay at -1 and %false is returned. If any pwq |
|
* has in flight commands, its pwq->flush_color is set to |
|
* @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq |
|
* wakeup logic is armed and %true is returned. |
|
* |
|
* The caller should have initialized @wq->first_flusher prior to |
|
* calling this function with non-negative @flush_color. If |
|
* @flush_color is negative, no flush color update is done and %false |
|
* is returned. |
|
* |
|
* If @work_color is non-negative, all pwqs should have the same |
|
* work_color which is previous to @work_color and all will be |
|
* advanced to @work_color. |
|
* |
|
* CONTEXT: |
|
* mutex_lock(wq->mutex). |
|
* |
|
* Return: |
|
* %true if @flush_color >= 0 and there's something to flush. %false |
|
* otherwise. |
|
*/ |
|
static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
|
int flush_color, int work_color) |
|
{ |
|
bool wait = false; |
|
struct pool_workqueue *pwq; |
|
|
|
if (flush_color >= 0) { |
|
WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); |
|
atomic_set(&wq->nr_pwqs_to_flush, 1); |
|
} |
|
|
|
for_each_pwq(pwq, wq) { |
|
struct worker_pool *pool = pwq->pool; |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
if (flush_color >= 0) { |
|
WARN_ON_ONCE(pwq->flush_color != -1); |
|
|
|
if (pwq->nr_in_flight[flush_color]) { |
|
pwq->flush_color = flush_color; |
|
atomic_inc(&wq->nr_pwqs_to_flush); |
|
wait = true; |
|
} |
|
} |
|
|
|
if (work_color >= 0) { |
|
WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); |
|
pwq->work_color = work_color; |
|
} |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
|
|
if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) |
|
complete(&wq->first_flusher->done); |
|
|
|
return wait; |
|
} |
|
|
|
/** |
|
* flush_workqueue - ensure that any scheduled work has run to completion. |
|
* @wq: workqueue to flush |
|
* |
|
* This function sleeps until all work items which were queued on entry |
|
* have finished execution, but it is not livelocked by new incoming ones. |
|
*/ |
|
void flush_workqueue(struct workqueue_struct *wq) |
|
{ |
|
struct wq_flusher this_flusher = { |
|
.list = LIST_HEAD_INIT(this_flusher.list), |
|
.flush_color = -1, |
|
.done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), |
|
}; |
|
int next_color; |
|
|
|
if (WARN_ON(!wq_online)) |
|
return; |
|
|
|
lock_map_acquire(&wq->lockdep_map); |
|
lock_map_release(&wq->lockdep_map); |
|
|
|
mutex_lock(&wq->mutex); |
|
|
|
/* |
|
* Start-to-wait phase |
|
*/ |
|
next_color = work_next_color(wq->work_color); |
|
|
|
if (next_color != wq->flush_color) { |
|
/* |
|
* Color space is not full. The current work_color |
|
* becomes our flush_color and work_color is advanced |
|
* by one. |
|
*/ |
|
WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); |
|
this_flusher.flush_color = wq->work_color; |
|
wq->work_color = next_color; |
|
|
|
if (!wq->first_flusher) { |
|
/* no flush in progress, become the first flusher */ |
|
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
|
|
|
wq->first_flusher = &this_flusher; |
|
|
|
if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, |
|
wq->work_color)) { |
|
/* nothing to flush, done */ |
|
wq->flush_color = next_color; |
|
wq->first_flusher = NULL; |
|
goto out_unlock; |
|
} |
|
} else { |
|
/* wait in queue */ |
|
WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); |
|
list_add_tail(&this_flusher.list, &wq->flusher_queue); |
|
flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
|
} |
|
} else { |
|
/* |
|
* Oops, color space is full, wait on overflow queue. |
|
* The next flush completion will assign us |
|
* flush_color and transfer to flusher_queue. |
|
*/ |
|
list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
|
} |
|
|
|
check_flush_dependency(wq, NULL); |
|
|
|
mutex_unlock(&wq->mutex); |
|
|
|
wait_for_completion(&this_flusher.done); |
|
|
|
/* |
|
* Wake-up-and-cascade phase |
|
* |
|
* First flushers are responsible for cascading flushes and |
|
* handling overflow. Non-first flushers can simply return. |
|
*/ |
|
if (READ_ONCE(wq->first_flusher) != &this_flusher) |
|
return; |
|
|
|
mutex_lock(&wq->mutex); |
|
|
|
/* we might have raced, check again with mutex held */ |
|
if (wq->first_flusher != &this_flusher) |
|
goto out_unlock; |
|
|
|
WRITE_ONCE(wq->first_flusher, NULL); |
|
|
|
WARN_ON_ONCE(!list_empty(&this_flusher.list)); |
|
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
|
|
|
while (true) { |
|
struct wq_flusher *next, *tmp; |
|
|
|
/* complete all the flushers sharing the current flush color */ |
|
list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
|
if (next->flush_color != wq->flush_color) |
|
break; |
|
list_del_init(&next->list); |
|
complete(&next->done); |
|
} |
|
|
|
WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && |
|
wq->flush_color != work_next_color(wq->work_color)); |
|
|
|
/* this flush_color is finished, advance by one */ |
|
wq->flush_color = work_next_color(wq->flush_color); |
|
|
|
/* one color has been freed, handle overflow queue */ |
|
if (!list_empty(&wq->flusher_overflow)) { |
|
/* |
|
* Assign the same color to all overflowed |
|
* flushers, advance work_color and append to |
|
* flusher_queue. This is the start-to-wait |
|
* phase for these overflowed flushers. |
|
*/ |
|
list_for_each_entry(tmp, &wq->flusher_overflow, list) |
|
tmp->flush_color = wq->work_color; |
|
|
|
wq->work_color = work_next_color(wq->work_color); |
|
|
|
list_splice_tail_init(&wq->flusher_overflow, |
|
&wq->flusher_queue); |
|
flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
|
} |
|
|
|
if (list_empty(&wq->flusher_queue)) { |
|
WARN_ON_ONCE(wq->flush_color != wq->work_color); |
|
break; |
|
} |
|
|
|
/* |
|
* Need to flush more colors. Make the next flusher |
|
* the new first flusher and arm pwqs. |
|
*/ |
|
WARN_ON_ONCE(wq->flush_color == wq->work_color); |
|
WARN_ON_ONCE(wq->flush_color != next->flush_color); |
|
|
|
list_del_init(&next->list); |
|
wq->first_flusher = next; |
|
|
|
if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) |
|
break; |
|
|
|
/* |
|
* Meh... this color is already done, clear first |
|
* flusher and repeat cascading. |
|
*/ |
|
wq->first_flusher = NULL; |
|
} |
|
|
|
out_unlock: |
|
mutex_unlock(&wq->mutex); |
|
} |
|
EXPORT_SYMBOL(flush_workqueue); |
|
|
|
/** |
|
* drain_workqueue - drain a workqueue |
|
* @wq: workqueue to drain |
|
* |
|
* Wait until the workqueue becomes empty. While draining is in progress, |
|
* only chain queueing is allowed. IOW, only currently pending or running |
|
* work items on @wq can queue further work items on it. @wq is flushed |
|
* repeatedly until it becomes empty. The number of flushing is determined |
|
* by the depth of chaining and should be relatively short. Whine if it |
|
* takes too long. |
|
*/ |
|
void drain_workqueue(struct workqueue_struct *wq) |
|
{ |
|
unsigned int flush_cnt = 0; |
|
struct pool_workqueue *pwq; |
|
|
|
/* |
|
* __queue_work() needs to test whether there are drainers, is much |
|
* hotter than drain_workqueue() and already looks at @wq->flags. |
|
* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. |
|
*/ |
|
mutex_lock(&wq->mutex); |
|
if (!wq->nr_drainers++) |
|
wq->flags |= __WQ_DRAINING; |
|
mutex_unlock(&wq->mutex); |
|
reflush: |
|
flush_workqueue(wq); |
|
|
|
mutex_lock(&wq->mutex); |
|
|
|
for_each_pwq(pwq, wq) { |
|
bool drained; |
|
|
|
raw_spin_lock_irq(&pwq->pool->lock); |
|
drained = !pwq->nr_active && list_empty(&pwq->inactive_works); |
|
raw_spin_unlock_irq(&pwq->pool->lock); |
|
|
|
if (drained) |
|
continue; |
|
|
|
if (++flush_cnt == 10 || |
|
(flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
|
pr_warn("workqueue %s: %s() isn't complete after %u tries\n", |
|
wq->name, __func__, flush_cnt); |
|
|
|
mutex_unlock(&wq->mutex); |
|
goto reflush; |
|
} |
|
|
|
if (!--wq->nr_drainers) |
|
wq->flags &= ~__WQ_DRAINING; |
|
mutex_unlock(&wq->mutex); |
|
} |
|
EXPORT_SYMBOL_GPL(drain_workqueue); |
|
|
|
static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, |
|
bool from_cancel) |
|
{ |
|
struct worker *worker = NULL; |
|
struct worker_pool *pool; |
|
struct pool_workqueue *pwq; |
|
|
|
might_sleep(); |
|
|
|
rcu_read_lock(); |
|
pool = get_work_pool(work); |
|
if (!pool) { |
|
rcu_read_unlock(); |
|
return false; |
|
} |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
/* see the comment in try_to_grab_pending() with the same code */ |
|
pwq = get_work_pwq(work); |
|
if (pwq) { |
|
if (unlikely(pwq->pool != pool)) |
|
goto already_gone; |
|
} else { |
|
worker = find_worker_executing_work(pool, work); |
|
if (!worker) |
|
goto already_gone; |
|
pwq = worker->current_pwq; |
|
} |
|
|
|
check_flush_dependency(pwq->wq, work); |
|
|
|
insert_wq_barrier(pwq, barr, work, worker); |
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
/* |
|
* Force a lock recursion deadlock when using flush_work() inside a |
|
* single-threaded or rescuer equipped workqueue. |
|
* |
|
* For single threaded workqueues the deadlock happens when the work |
|
* is after the work issuing the flush_work(). For rescuer equipped |
|
* workqueues the deadlock happens when the rescuer stalls, blocking |
|
* forward progress. |
|
*/ |
|
if (!from_cancel && |
|
(pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { |
|
lock_map_acquire(&pwq->wq->lockdep_map); |
|
lock_map_release(&pwq->wq->lockdep_map); |
|
} |
|
rcu_read_unlock(); |
|
return true; |
|
already_gone: |
|
raw_spin_unlock_irq(&pool->lock); |
|
rcu_read_unlock(); |
|
return false; |
|
} |
|
|
|
static bool __flush_work(struct work_struct *work, bool from_cancel) |
|
{ |
|
struct wq_barrier barr; |
|
|
|
if (WARN_ON(!wq_online)) |
|
return false; |
|
|
|
if (WARN_ON(!work->func)) |
|
return false; |
|
|
|
if (!from_cancel) { |
|
lock_map_acquire(&work->lockdep_map); |
|
lock_map_release(&work->lockdep_map); |
|
} |
|
|
|
if (start_flush_work(work, &barr, from_cancel)) { |
|
wait_for_completion(&barr.done); |
|
destroy_work_on_stack(&barr.work); |
|
return true; |
|
} else { |
|
return false; |
|
} |
|
} |
|
|
|
/** |
|
* flush_work - wait for a work to finish executing the last queueing instance |
|
* @work: the work to flush |
|
* |
|
* Wait until @work has finished execution. @work is guaranteed to be idle |
|
* on return if it hasn't been requeued since flush started. |
|
* |
|
* Return: |
|
* %true if flush_work() waited for the work to finish execution, |
|
* %false if it was already idle. |
|
*/ |
|
bool flush_work(struct work_struct *work) |
|
{ |
|
return __flush_work(work, false); |
|
} |
|
EXPORT_SYMBOL_GPL(flush_work); |
|
|
|
struct cwt_wait { |
|
wait_queue_entry_t wait; |
|
struct work_struct *work; |
|
}; |
|
|
|
static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) |
|
{ |
|
struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); |
|
|
|
if (cwait->work != key) |
|
return 0; |
|
return autoremove_wake_function(wait, mode, sync, key); |
|
} |
|
|
|
static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
|
{ |
|
static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); |
|
unsigned long flags; |
|
int ret; |
|
|
|
do { |
|
ret = try_to_grab_pending(work, is_dwork, &flags); |
|
/* |
|
* If someone else is already canceling, wait for it to |
|
* finish. flush_work() doesn't work for PREEMPT_NONE |
|
* because we may get scheduled between @work's completion |
|
* and the other canceling task resuming and clearing |
|
* CANCELING - flush_work() will return false immediately |
|
* as @work is no longer busy, try_to_grab_pending() will |
|
* return -ENOENT as @work is still being canceled and the |
|
* other canceling task won't be able to clear CANCELING as |
|
* we're hogging the CPU. |
|
* |
|
* Let's wait for completion using a waitqueue. As this |
|
* may lead to the thundering herd problem, use a custom |
|
* wake function which matches @work along with exclusive |
|
* wait and wakeup. |
|
*/ |
|
if (unlikely(ret == -ENOENT)) { |
|
struct cwt_wait cwait; |
|
|
|
init_wait(&cwait.wait); |
|
cwait.wait.func = cwt_wakefn; |
|
cwait.work = work; |
|
|
|
prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, |
|
TASK_UNINTERRUPTIBLE); |
|
if (work_is_canceling(work)) |
|
schedule(); |
|
finish_wait(&cancel_waitq, &cwait.wait); |
|
} |
|
} while (unlikely(ret < 0)); |
|
|
|
/* tell other tasks trying to grab @work to back off */ |
|
mark_work_canceling(work); |
|
local_irq_restore(flags); |
|
|
|
/* |
|
* This allows canceling during early boot. We know that @work |
|
* isn't executing. |
|
*/ |
|
if (wq_online) |
|
__flush_work(work, true); |
|
|
|
clear_work_data(work); |
|
|
|
/* |
|
* Paired with prepare_to_wait() above so that either |
|
* waitqueue_active() is visible here or !work_is_canceling() is |
|
* visible there. |
|
*/ |
|
smp_mb(); |
|
if (waitqueue_active(&cancel_waitq)) |
|
__wake_up(&cancel_waitq, TASK_NORMAL, 1, work); |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cancel_work_sync - cancel a work and wait for it to finish |
|
* @work: the work to cancel |
|
* |
|
* Cancel @work and wait for its execution to finish. This function |
|
* can be used even if the work re-queues itself or migrates to |
|
* another workqueue. On return from this function, @work is |
|
* guaranteed to be not pending or executing on any CPU. |
|
* |
|
* cancel_work_sync(&delayed_work->work) must not be used for |
|
* delayed_work's. Use cancel_delayed_work_sync() instead. |
|
* |
|
* The caller must ensure that the workqueue on which @work was last |
|
* queued can't be destroyed before this function returns. |
|
* |
|
* Return: |
|
* %true if @work was pending, %false otherwise. |
|
*/ |
|
bool cancel_work_sync(struct work_struct *work) |
|
{ |
|
return __cancel_work_timer(work, false); |
|
} |
|
EXPORT_SYMBOL_GPL(cancel_work_sync); |
|
|
|
/** |
|
* flush_delayed_work - wait for a dwork to finish executing the last queueing |
|
* @dwork: the delayed work to flush |
|
* |
|
* Delayed timer is cancelled and the pending work is queued for |
|
* immediate execution. Like flush_work(), this function only |
|
* considers the last queueing instance of @dwork. |
|
* |
|
* Return: |
|
* %true if flush_work() waited for the work to finish execution, |
|
* %false if it was already idle. |
|
*/ |
|
bool flush_delayed_work(struct delayed_work *dwork) |
|
{ |
|
local_irq_disable(); |
|
if (del_timer_sync(&dwork->timer)) |
|
__queue_work(dwork->cpu, dwork->wq, &dwork->work); |
|
local_irq_enable(); |
|
return flush_work(&dwork->work); |
|
} |
|
EXPORT_SYMBOL(flush_delayed_work); |
|
|
|
/** |
|
* flush_rcu_work - wait for a rwork to finish executing the last queueing |
|
* @rwork: the rcu work to flush |
|
* |
|
* Return: |
|
* %true if flush_rcu_work() waited for the work to finish execution, |
|
* %false if it was already idle. |
|
*/ |
|
bool flush_rcu_work(struct rcu_work *rwork) |
|
{ |
|
if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { |
|
rcu_barrier(); |
|
flush_work(&rwork->work); |
|
return true; |
|
} else { |
|
return flush_work(&rwork->work); |
|
} |
|
} |
|
EXPORT_SYMBOL(flush_rcu_work); |
|
|
|
static bool __cancel_work(struct work_struct *work, bool is_dwork) |
|
{ |
|
unsigned long flags; |
|
int ret; |
|
|
|
do { |
|
ret = try_to_grab_pending(work, is_dwork, &flags); |
|
} while (unlikely(ret == -EAGAIN)); |
|
|
|
if (unlikely(ret < 0)) |
|
return false; |
|
|
|
set_work_pool_and_clear_pending(work, get_work_pool_id(work)); |
|
local_irq_restore(flags); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cancel_delayed_work - cancel a delayed work |
|
* @dwork: delayed_work to cancel |
|
* |
|
* Kill off a pending delayed_work. |
|
* |
|
* Return: %true if @dwork was pending and canceled; %false if it wasn't |
|
* pending. |
|
* |
|
* Note: |
|
* The work callback function may still be running on return, unless |
|
* it returns %true and the work doesn't re-arm itself. Explicitly flush or |
|
* use cancel_delayed_work_sync() to wait on it. |
|
* |
|
* This function is safe to call from any context including IRQ handler. |
|
*/ |
|
bool cancel_delayed_work(struct delayed_work *dwork) |
|
{ |
|
return __cancel_work(&dwork->work, true); |
|
} |
|
EXPORT_SYMBOL(cancel_delayed_work); |
|
|
|
/** |
|
* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
|
* @dwork: the delayed work cancel |
|
* |
|
* This is cancel_work_sync() for delayed works. |
|
* |
|
* Return: |
|
* %true if @dwork was pending, %false otherwise. |
|
*/ |
|
bool cancel_delayed_work_sync(struct delayed_work *dwork) |
|
{ |
|
return __cancel_work_timer(&dwork->work, true); |
|
} |
|
EXPORT_SYMBOL(cancel_delayed_work_sync); |
|
|
|
/** |
|
* schedule_on_each_cpu - execute a function synchronously on each online CPU |
|
* @func: the function to call |
|
* |
|
* schedule_on_each_cpu() executes @func on each online CPU using the |
|
* system workqueue and blocks until all CPUs have completed. |
|
* schedule_on_each_cpu() is very slow. |
|
* |
|
* Return: |
|
* 0 on success, -errno on failure. |
|
*/ |
|
int schedule_on_each_cpu(work_func_t func) |
|
{ |
|
int cpu; |
|
struct work_struct __percpu *works; |
|
|
|
works = alloc_percpu(struct work_struct); |
|
if (!works) |
|
return -ENOMEM; |
|
|
|
cpus_read_lock(); |
|
|
|
for_each_online_cpu(cpu) { |
|
struct work_struct *work = per_cpu_ptr(works, cpu); |
|
|
|
INIT_WORK(work, func); |
|
schedule_work_on(cpu, work); |
|
} |
|
|
|
for_each_online_cpu(cpu) |
|
flush_work(per_cpu_ptr(works, cpu)); |
|
|
|
cpus_read_unlock(); |
|
free_percpu(works); |
|
return 0; |
|
} |
|
|
|
/** |
|
* execute_in_process_context - reliably execute the routine with user context |
|
* @fn: the function to execute |
|
* @ew: guaranteed storage for the execute work structure (must |
|
* be available when the work executes) |
|
* |
|
* Executes the function immediately if process context is available, |
|
* otherwise schedules the function for delayed execution. |
|
* |
|
* Return: 0 - function was executed |
|
* 1 - function was scheduled for execution |
|
*/ |
|
int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
|
{ |
|
if (!in_interrupt()) { |
|
fn(&ew->work); |
|
return 0; |
|
} |
|
|
|
INIT_WORK(&ew->work, fn); |
|
schedule_work(&ew->work); |
|
|
|
return 1; |
|
} |
|
EXPORT_SYMBOL_GPL(execute_in_process_context); |
|
|
|
/** |
|
* free_workqueue_attrs - free a workqueue_attrs |
|
* @attrs: workqueue_attrs to free |
|
* |
|
* Undo alloc_workqueue_attrs(). |
|
*/ |
|
void free_workqueue_attrs(struct workqueue_attrs *attrs) |
|
{ |
|
if (attrs) { |
|
free_cpumask_var(attrs->cpumask); |
|
kfree(attrs); |
|
} |
|
} |
|
|
|
/** |
|
* alloc_workqueue_attrs - allocate a workqueue_attrs |
|
* |
|
* Allocate a new workqueue_attrs, initialize with default settings and |
|
* return it. |
|
* |
|
* Return: The allocated new workqueue_attr on success. %NULL on failure. |
|
*/ |
|
struct workqueue_attrs *alloc_workqueue_attrs(void) |
|
{ |
|
struct workqueue_attrs *attrs; |
|
|
|
attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); |
|
if (!attrs) |
|
goto fail; |
|
if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) |
|
goto fail; |
|
|
|
cpumask_copy(attrs->cpumask, cpu_possible_mask); |
|
return attrs; |
|
fail: |
|
free_workqueue_attrs(attrs); |
|
return NULL; |
|
} |
|
|
|
static void copy_workqueue_attrs(struct workqueue_attrs *to, |
|
const struct workqueue_attrs *from) |
|
{ |
|
to->nice = from->nice; |
|
cpumask_copy(to->cpumask, from->cpumask); |
|
/* |
|
* Unlike hash and equality test, this function doesn't ignore |
|
* ->no_numa as it is used for both pool and wq attrs. Instead, |
|
* get_unbound_pool() explicitly clears ->no_numa after copying. |
|
*/ |
|
to->no_numa = from->no_numa; |
|
} |
|
|
|
/* hash value of the content of @attr */ |
|
static u32 wqattrs_hash(const struct workqueue_attrs *attrs) |
|
{ |
|
u32 hash = 0; |
|
|
|
hash = jhash_1word(attrs->nice, hash); |
|
hash = jhash(cpumask_bits(attrs->cpumask), |
|
BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); |
|
return hash; |
|
} |
|
|
|
/* content equality test */ |
|
static bool wqattrs_equal(const struct workqueue_attrs *a, |
|
const struct workqueue_attrs *b) |
|
{ |
|
if (a->nice != b->nice) |
|
return false; |
|
if (!cpumask_equal(a->cpumask, b->cpumask)) |
|
return false; |
|
return true; |
|
} |
|
|
|
/** |
|
* init_worker_pool - initialize a newly zalloc'd worker_pool |
|
* @pool: worker_pool to initialize |
|
* |
|
* Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. |
|
* |
|
* Return: 0 on success, -errno on failure. Even on failure, all fields |
|
* inside @pool proper are initialized and put_unbound_pool() can be called |
|
* on @pool safely to release it. |
|
*/ |
|
static int init_worker_pool(struct worker_pool *pool) |
|
{ |
|
raw_spin_lock_init(&pool->lock); |
|
pool->id = -1; |
|
pool->cpu = -1; |
|
pool->node = NUMA_NO_NODE; |
|
pool->flags |= POOL_DISASSOCIATED; |
|
pool->watchdog_ts = jiffies; |
|
INIT_LIST_HEAD(&pool->worklist); |
|
INIT_LIST_HEAD(&pool->idle_list); |
|
hash_init(pool->busy_hash); |
|
|
|
timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); |
|
|
|
timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); |
|
|
|
INIT_LIST_HEAD(&pool->workers); |
|
|
|
ida_init(&pool->worker_ida); |
|
INIT_HLIST_NODE(&pool->hash_node); |
|
pool->refcnt = 1; |
|
|
|
/* shouldn't fail above this point */ |
|
pool->attrs = alloc_workqueue_attrs(); |
|
if (!pool->attrs) |
|
return -ENOMEM; |
|
return 0; |
|
} |
|
|
|
#ifdef CONFIG_LOCKDEP |
|
static void wq_init_lockdep(struct workqueue_struct *wq) |
|
{ |
|
char *lock_name; |
|
|
|
lockdep_register_key(&wq->key); |
|
lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); |
|
if (!lock_name) |
|
lock_name = wq->name; |
|
|
|
wq->lock_name = lock_name; |
|
lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0); |
|
} |
|
|
|
static void wq_unregister_lockdep(struct workqueue_struct *wq) |
|
{ |
|
lockdep_unregister_key(&wq->key); |
|
} |
|
|
|
static void wq_free_lockdep(struct workqueue_struct *wq) |
|
{ |
|
if (wq->lock_name != wq->name) |
|
kfree(wq->lock_name); |
|
} |
|
#else |
|
static void wq_init_lockdep(struct workqueue_struct *wq) |
|
{ |
|
} |
|
|
|
static void wq_unregister_lockdep(struct workqueue_struct *wq) |
|
{ |
|
} |
|
|
|
static void wq_free_lockdep(struct workqueue_struct *wq) |
|
{ |
|
} |
|
#endif |
|
|
|
static void rcu_free_wq(struct rcu_head *rcu) |
|
{ |
|
struct workqueue_struct *wq = |
|
container_of(rcu, struct workqueue_struct, rcu); |
|
|
|
wq_free_lockdep(wq); |
|
|
|
if (!(wq->flags & WQ_UNBOUND)) |
|
free_percpu(wq->cpu_pwqs); |
|
else |
|
free_workqueue_attrs(wq->unbound_attrs); |
|
|
|
kfree(wq); |
|
} |
|
|
|
static void rcu_free_pool(struct rcu_head *rcu) |
|
{ |
|
struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); |
|
|
|
ida_destroy(&pool->worker_ida); |
|
free_workqueue_attrs(pool->attrs); |
|
kfree(pool); |
|
} |
|
|
|
/* This returns with the lock held on success (pool manager is inactive). */ |
|
static bool wq_manager_inactive(struct worker_pool *pool) |
|
{ |
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
if (pool->flags & POOL_MANAGER_ACTIVE) { |
|
raw_spin_unlock_irq(&pool->lock); |
|
return false; |
|
} |
|
return true; |
|
} |
|
|
|
/** |
|
* put_unbound_pool - put a worker_pool |
|
* @pool: worker_pool to put |
|
* |
|
* Put @pool. If its refcnt reaches zero, it gets destroyed in RCU |
|
* safe manner. get_unbound_pool() calls this function on its failure path |
|
* and this function should be able to release pools which went through, |
|
* successfully or not, init_worker_pool(). |
|
* |
|
* Should be called with wq_pool_mutex held. |
|
*/ |
|
static void put_unbound_pool(struct worker_pool *pool) |
|
{ |
|
DECLARE_COMPLETION_ONSTACK(detach_completion); |
|
struct worker *worker; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
if (--pool->refcnt) |
|
return; |
|
|
|
/* sanity checks */ |
|
if (WARN_ON(!(pool->cpu < 0)) || |
|
WARN_ON(!list_empty(&pool->worklist))) |
|
return; |
|
|
|
/* release id and unhash */ |
|
if (pool->id >= 0) |
|
idr_remove(&worker_pool_idr, pool->id); |
|
hash_del(&pool->hash_node); |
|
|
|
/* |
|
* Become the manager and destroy all workers. This prevents |
|
* @pool's workers from blocking on attach_mutex. We're the last |
|
* manager and @pool gets freed with the flag set. |
|
* Because of how wq_manager_inactive() works, we will hold the |
|
* spinlock after a successful wait. |
|
*/ |
|
rcuwait_wait_event(&manager_wait, wq_manager_inactive(pool), |
|
TASK_UNINTERRUPTIBLE); |
|
pool->flags |= POOL_MANAGER_ACTIVE; |
|
|
|
while ((worker = first_idle_worker(pool))) |
|
destroy_worker(worker); |
|
WARN_ON(pool->nr_workers || pool->nr_idle); |
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
mutex_lock(&wq_pool_attach_mutex); |
|
if (!list_empty(&pool->workers)) |
|
pool->detach_completion = &detach_completion; |
|
mutex_unlock(&wq_pool_attach_mutex); |
|
|
|
if (pool->detach_completion) |
|
wait_for_completion(pool->detach_completion); |
|
|
|
/* shut down the timers */ |
|
del_timer_sync(&pool->idle_timer); |
|
del_timer_sync(&pool->mayday_timer); |
|
|
|
/* RCU protected to allow dereferences from get_work_pool() */ |
|
call_rcu(&pool->rcu, rcu_free_pool); |
|
} |
|
|
|
/** |
|
* get_unbound_pool - get a worker_pool with the specified attributes |
|
* @attrs: the attributes of the worker_pool to get |
|
* |
|
* Obtain a worker_pool which has the same attributes as @attrs, bump the |
|
* reference count and return it. If there already is a matching |
|
* worker_pool, it will be used; otherwise, this function attempts to |
|
* create a new one. |
|
* |
|
* Should be called with wq_pool_mutex held. |
|
* |
|
* Return: On success, a worker_pool with the same attributes as @attrs. |
|
* On failure, %NULL. |
|
*/ |
|
static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) |
|
{ |
|
u32 hash = wqattrs_hash(attrs); |
|
struct worker_pool *pool; |
|
int node; |
|
int target_node = NUMA_NO_NODE; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
/* do we already have a matching pool? */ |
|
hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { |
|
if (wqattrs_equal(pool->attrs, attrs)) { |
|
pool->refcnt++; |
|
return pool; |
|
} |
|
} |
|
|
|
/* if cpumask is contained inside a NUMA node, we belong to that node */ |
|
if (wq_numa_enabled) { |
|
for_each_node(node) { |
|
if (cpumask_subset(attrs->cpumask, |
|
wq_numa_possible_cpumask[node])) { |
|
target_node = node; |
|
break; |
|
} |
|
} |
|
} |
|
|
|
/* nope, create a new one */ |
|
pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node); |
|
if (!pool || init_worker_pool(pool) < 0) |
|
goto fail; |
|
|
|
lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ |
|
copy_workqueue_attrs(pool->attrs, attrs); |
|
pool->node = target_node; |
|
|
|
/* |
|
* no_numa isn't a worker_pool attribute, always clear it. See |
|
* 'struct workqueue_attrs' comments for detail. |
|
*/ |
|
pool->attrs->no_numa = false; |
|
|
|
if (worker_pool_assign_id(pool) < 0) |
|
goto fail; |
|
|
|
/* create and start the initial worker */ |
|
if (wq_online && !create_worker(pool)) |
|
goto fail; |
|
|
|
/* install */ |
|
hash_add(unbound_pool_hash, &pool->hash_node, hash); |
|
|
|
return pool; |
|
fail: |
|
if (pool) |
|
put_unbound_pool(pool); |
|
return NULL; |
|
} |
|
|
|
static void rcu_free_pwq(struct rcu_head *rcu) |
|
{ |
|
kmem_cache_free(pwq_cache, |
|
container_of(rcu, struct pool_workqueue, rcu)); |
|
} |
|
|
|
/* |
|
* Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt |
|
* and needs to be destroyed. |
|
*/ |
|
static void pwq_unbound_release_workfn(struct work_struct *work) |
|
{ |
|
struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, |
|
unbound_release_work); |
|
struct workqueue_struct *wq = pwq->wq; |
|
struct worker_pool *pool = pwq->pool; |
|
bool is_last = false; |
|
|
|
/* |
|
* when @pwq is not linked, it doesn't hold any reference to the |
|
* @wq, and @wq is invalid to access. |
|
*/ |
|
if (!list_empty(&pwq->pwqs_node)) { |
|
if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) |
|
return; |
|
|
|
mutex_lock(&wq->mutex); |
|
list_del_rcu(&pwq->pwqs_node); |
|
is_last = list_empty(&wq->pwqs); |
|
mutex_unlock(&wq->mutex); |
|
} |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
put_unbound_pool(pool); |
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
call_rcu(&pwq->rcu, rcu_free_pwq); |
|
|
|
/* |
|
* If we're the last pwq going away, @wq is already dead and no one |
|
* is gonna access it anymore. Schedule RCU free. |
|
*/ |
|
if (is_last) { |
|
wq_unregister_lockdep(wq); |
|
call_rcu(&wq->rcu, rcu_free_wq); |
|
} |
|
} |
|
|
|
/** |
|
* pwq_adjust_max_active - update a pwq's max_active to the current setting |
|
* @pwq: target pool_workqueue |
|
* |
|
* If @pwq isn't freezing, set @pwq->max_active to the associated |
|
* workqueue's saved_max_active and activate inactive work items |
|
* accordingly. If @pwq is freezing, clear @pwq->max_active to zero. |
|
*/ |
|
static void pwq_adjust_max_active(struct pool_workqueue *pwq) |
|
{ |
|
struct workqueue_struct *wq = pwq->wq; |
|
bool freezable = wq->flags & WQ_FREEZABLE; |
|
unsigned long flags; |
|
|
|
/* for @wq->saved_max_active */ |
|
lockdep_assert_held(&wq->mutex); |
|
|
|
/* fast exit for non-freezable wqs */ |
|
if (!freezable && pwq->max_active == wq->saved_max_active) |
|
return; |
|
|
|
/* this function can be called during early boot w/ irq disabled */ |
|
raw_spin_lock_irqsave(&pwq->pool->lock, flags); |
|
|
|
/* |
|
* During [un]freezing, the caller is responsible for ensuring that |
|
* this function is called at least once after @workqueue_freezing |
|
* is updated and visible. |
|
*/ |
|
if (!freezable || !workqueue_freezing) { |
|
bool kick = false; |
|
|
|
pwq->max_active = wq->saved_max_active; |
|
|
|
while (!list_empty(&pwq->inactive_works) && |
|
pwq->nr_active < pwq->max_active) { |
|
pwq_activate_first_inactive(pwq); |
|
kick = true; |
|
} |
|
|
|
/* |
|
* Need to kick a worker after thawed or an unbound wq's |
|
* max_active is bumped. In realtime scenarios, always kicking a |
|
* worker will cause interference on the isolated cpu cores, so |
|
* let's kick iff work items were activated. |
|
*/ |
|
if (kick) |
|
wake_up_worker(pwq->pool); |
|
} else { |
|
pwq->max_active = 0; |
|
} |
|
|
|
raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); |
|
} |
|
|
|
/* initialize newly allocated @pwq which is associated with @wq and @pool */ |
|
static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, |
|
struct worker_pool *pool) |
|
{ |
|
BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
|
|
|
memset(pwq, 0, sizeof(*pwq)); |
|
|
|
pwq->pool = pool; |
|
pwq->wq = wq; |
|
pwq->flush_color = -1; |
|
pwq->refcnt = 1; |
|
INIT_LIST_HEAD(&pwq->inactive_works); |
|
INIT_LIST_HEAD(&pwq->pwqs_node); |
|
INIT_LIST_HEAD(&pwq->mayday_node); |
|
INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); |
|
} |
|
|
|
/* sync @pwq with the current state of its associated wq and link it */ |
|
static void link_pwq(struct pool_workqueue *pwq) |
|
{ |
|
struct workqueue_struct *wq = pwq->wq; |
|
|
|
lockdep_assert_held(&wq->mutex); |
|
|
|
/* may be called multiple times, ignore if already linked */ |
|
if (!list_empty(&pwq->pwqs_node)) |
|
return; |
|
|
|
/* set the matching work_color */ |
|
pwq->work_color = wq->work_color; |
|
|
|
/* sync max_active to the current setting */ |
|
pwq_adjust_max_active(pwq); |
|
|
|
/* link in @pwq */ |
|
list_add_rcu(&pwq->pwqs_node, &wq->pwqs); |
|
} |
|
|
|
/* obtain a pool matching @attr and create a pwq associating the pool and @wq */ |
|
static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, |
|
const struct workqueue_attrs *attrs) |
|
{ |
|
struct worker_pool *pool; |
|
struct pool_workqueue *pwq; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
pool = get_unbound_pool(attrs); |
|
if (!pool) |
|
return NULL; |
|
|
|
pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); |
|
if (!pwq) { |
|
put_unbound_pool(pool); |
|
return NULL; |
|
} |
|
|
|
init_pwq(pwq, wq, pool); |
|
return pwq; |
|
} |
|
|
|
/** |
|
* wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node |
|
* @attrs: the wq_attrs of the default pwq of the target workqueue |
|
* @node: the target NUMA node |
|
* @cpu_going_down: if >= 0, the CPU to consider as offline |
|
* @cpumask: outarg, the resulting cpumask |
|
* |
|
* Calculate the cpumask a workqueue with @attrs should use on @node. If |
|
* @cpu_going_down is >= 0, that cpu is considered offline during |
|
* calculation. The result is stored in @cpumask. |
|
* |
|
* If NUMA affinity is not enabled, @attrs->cpumask is always used. If |
|
* enabled and @node has online CPUs requested by @attrs, the returned |
|
* cpumask is the intersection of the possible CPUs of @node and |
|
* @attrs->cpumask. |
|
* |
|
* The caller is responsible for ensuring that the cpumask of @node stays |
|
* stable. |
|
* |
|
* Return: %true if the resulting @cpumask is different from @attrs->cpumask, |
|
* %false if equal. |
|
*/ |
|
static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, |
|
int cpu_going_down, cpumask_t *cpumask) |
|
{ |
|
if (!wq_numa_enabled || attrs->no_numa) |
|
goto use_dfl; |
|
|
|
/* does @node have any online CPUs @attrs wants? */ |
|
cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); |
|
if (cpu_going_down >= 0) |
|
cpumask_clear_cpu(cpu_going_down, cpumask); |
|
|
|
if (cpumask_empty(cpumask)) |
|
goto use_dfl; |
|
|
|
/* yeap, return possible CPUs in @node that @attrs wants */ |
|
cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); |
|
|
|
if (cpumask_empty(cpumask)) { |
|
pr_warn_once("WARNING: workqueue cpumask: online intersect > " |
|
"possible intersect\n"); |
|
return false; |
|
} |
|
|
|
return !cpumask_equal(cpumask, attrs->cpumask); |
|
|
|
use_dfl: |
|
cpumask_copy(cpumask, attrs->cpumask); |
|
return false; |
|
} |
|
|
|
/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ |
|
static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, |
|
int node, |
|
struct pool_workqueue *pwq) |
|
{ |
|
struct pool_workqueue *old_pwq; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
lockdep_assert_held(&wq->mutex); |
|
|
|
/* link_pwq() can handle duplicate calls */ |
|
link_pwq(pwq); |
|
|
|
old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
|
rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); |
|
return old_pwq; |
|
} |
|
|
|
/* context to store the prepared attrs & pwqs before applying */ |
|
struct apply_wqattrs_ctx { |
|
struct workqueue_struct *wq; /* target workqueue */ |
|
struct workqueue_attrs *attrs; /* attrs to apply */ |
|
struct list_head list; /* queued for batching commit */ |
|
struct pool_workqueue *dfl_pwq; |
|
struct pool_workqueue *pwq_tbl[]; |
|
}; |
|
|
|
/* free the resources after success or abort */ |
|
static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) |
|
{ |
|
if (ctx) { |
|
int node; |
|
|
|
for_each_node(node) |
|
put_pwq_unlocked(ctx->pwq_tbl[node]); |
|
put_pwq_unlocked(ctx->dfl_pwq); |
|
|
|
free_workqueue_attrs(ctx->attrs); |
|
|
|
kfree(ctx); |
|
} |
|
} |
|
|
|
/* allocate the attrs and pwqs for later installation */ |
|
static struct apply_wqattrs_ctx * |
|
apply_wqattrs_prepare(struct workqueue_struct *wq, |
|
const struct workqueue_attrs *attrs) |
|
{ |
|
struct apply_wqattrs_ctx *ctx; |
|
struct workqueue_attrs *new_attrs, *tmp_attrs; |
|
int node; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL); |
|
|
|
new_attrs = alloc_workqueue_attrs(); |
|
tmp_attrs = alloc_workqueue_attrs(); |
|
if (!ctx || !new_attrs || !tmp_attrs) |
|
goto out_free; |
|
|
|
/* |
|
* Calculate the attrs of the default pwq. |
|
* If the user configured cpumask doesn't overlap with the |
|
* wq_unbound_cpumask, we fallback to the wq_unbound_cpumask. |
|
*/ |
|
copy_workqueue_attrs(new_attrs, attrs); |
|
cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask); |
|
if (unlikely(cpumask_empty(new_attrs->cpumask))) |
|
cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask); |
|
|
|
/* |
|
* We may create multiple pwqs with differing cpumasks. Make a |
|
* copy of @new_attrs which will be modified and used to obtain |
|
* pools. |
|
*/ |
|
copy_workqueue_attrs(tmp_attrs, new_attrs); |
|
|
|
/* |
|
* If something goes wrong during CPU up/down, we'll fall back to |
|
* the default pwq covering whole @attrs->cpumask. Always create |
|
* it even if we don't use it immediately. |
|
*/ |
|
ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); |
|
if (!ctx->dfl_pwq) |
|
goto out_free; |
|
|
|
for_each_node(node) { |
|
if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) { |
|
ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); |
|
if (!ctx->pwq_tbl[node]) |
|
goto out_free; |
|
} else { |
|
ctx->dfl_pwq->refcnt++; |
|
ctx->pwq_tbl[node] = ctx->dfl_pwq; |
|
} |
|
} |
|
|
|
/* save the user configured attrs and sanitize it. */ |
|
copy_workqueue_attrs(new_attrs, attrs); |
|
cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); |
|
ctx->attrs = new_attrs; |
|
|
|
ctx->wq = wq; |
|
free_workqueue_attrs(tmp_attrs); |
|
return ctx; |
|
|
|
out_free: |
|
free_workqueue_attrs(tmp_attrs); |
|
free_workqueue_attrs(new_attrs); |
|
apply_wqattrs_cleanup(ctx); |
|
return NULL; |
|
} |
|
|
|
/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ |
|
static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) |
|
{ |
|
int node; |
|
|
|
/* all pwqs have been created successfully, let's install'em */ |
|
mutex_lock(&ctx->wq->mutex); |
|
|
|
copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); |
|
|
|
/* save the previous pwq and install the new one */ |
|
for_each_node(node) |
|
ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node, |
|
ctx->pwq_tbl[node]); |
|
|
|
/* @dfl_pwq might not have been used, ensure it's linked */ |
|
link_pwq(ctx->dfl_pwq); |
|
swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); |
|
|
|
mutex_unlock(&ctx->wq->mutex); |
|
} |
|
|
|
static void apply_wqattrs_lock(void) |
|
{ |
|
/* CPUs should stay stable across pwq creations and installations */ |
|
cpus_read_lock(); |
|
mutex_lock(&wq_pool_mutex); |
|
} |
|
|
|
static void apply_wqattrs_unlock(void) |
|
{ |
|
mutex_unlock(&wq_pool_mutex); |
|
cpus_read_unlock(); |
|
} |
|
|
|
static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, |
|
const struct workqueue_attrs *attrs) |
|
{ |
|
struct apply_wqattrs_ctx *ctx; |
|
|
|
/* only unbound workqueues can change attributes */ |
|
if (WARN_ON(!(wq->flags & WQ_UNBOUND))) |
|
return -EINVAL; |
|
|
|
/* creating multiple pwqs breaks ordering guarantee */ |
|
if (!list_empty(&wq->pwqs)) { |
|
if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
|
return -EINVAL; |
|
|
|
wq->flags &= ~__WQ_ORDERED; |
|
} |
|
|
|
ctx = apply_wqattrs_prepare(wq, attrs); |
|
if (!ctx) |
|
return -ENOMEM; |
|
|
|
/* the ctx has been prepared successfully, let's commit it */ |
|
apply_wqattrs_commit(ctx); |
|
apply_wqattrs_cleanup(ctx); |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue |
|
* @wq: the target workqueue |
|
* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() |
|
* |
|
* Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA |
|
* machines, this function maps a separate pwq to each NUMA node with |
|
* possibles CPUs in @attrs->cpumask so that work items are affine to the |
|
* NUMA node it was issued on. Older pwqs are released as in-flight work |
|
* items finish. Note that a work item which repeatedly requeues itself |
|
* back-to-back will stay on its current pwq. |
|
* |
|
* Performs GFP_KERNEL allocations. |
|
* |
|
* Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock(). |
|
* |
|
* Return: 0 on success and -errno on failure. |
|
*/ |
|
int apply_workqueue_attrs(struct workqueue_struct *wq, |
|
const struct workqueue_attrs *attrs) |
|
{ |
|
int ret; |
|
|
|
lockdep_assert_cpus_held(); |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
ret = apply_workqueue_attrs_locked(wq, attrs); |
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug |
|
* @wq: the target workqueue |
|
* @cpu: the CPU coming up or going down |
|
* @online: whether @cpu is coming up or going down |
|
* |
|
* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and |
|
* %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of |
|
* @wq accordingly. |
|
* |
|
* If NUMA affinity can't be adjusted due to memory allocation failure, it |
|
* falls back to @wq->dfl_pwq which may not be optimal but is always |
|
* correct. |
|
* |
|
* Note that when the last allowed CPU of a NUMA node goes offline for a |
|
* workqueue with a cpumask spanning multiple nodes, the workers which were |
|
* already executing the work items for the workqueue will lose their CPU |
|
* affinity and may execute on any CPU. This is similar to how per-cpu |
|
* workqueues behave on CPU_DOWN. If a workqueue user wants strict |
|
* affinity, it's the user's responsibility to flush the work item from |
|
* CPU_DOWN_PREPARE. |
|
*/ |
|
static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, |
|
bool online) |
|
{ |
|
int node = cpu_to_node(cpu); |
|
int cpu_off = online ? -1 : cpu; |
|
struct pool_workqueue *old_pwq = NULL, *pwq; |
|
struct workqueue_attrs *target_attrs; |
|
cpumask_t *cpumask; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) || |
|
wq->unbound_attrs->no_numa) |
|
return; |
|
|
|
/* |
|
* We don't wanna alloc/free wq_attrs for each wq for each CPU. |
|
* Let's use a preallocated one. The following buf is protected by |
|
* CPU hotplug exclusion. |
|
*/ |
|
target_attrs = wq_update_unbound_numa_attrs_buf; |
|
cpumask = target_attrs->cpumask; |
|
|
|
copy_workqueue_attrs(target_attrs, wq->unbound_attrs); |
|
pwq = unbound_pwq_by_node(wq, node); |
|
|
|
/* |
|
* Let's determine what needs to be done. If the target cpumask is |
|
* different from the default pwq's, we need to compare it to @pwq's |
|
* and create a new one if they don't match. If the target cpumask |
|
* equals the default pwq's, the default pwq should be used. |
|
*/ |
|
if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) { |
|
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) |
|
return; |
|
} else { |
|
goto use_dfl_pwq; |
|
} |
|
|
|
/* create a new pwq */ |
|
pwq = alloc_unbound_pwq(wq, target_attrs); |
|
if (!pwq) { |
|
pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", |
|
wq->name); |
|
goto use_dfl_pwq; |
|
} |
|
|
|
/* Install the new pwq. */ |
|
mutex_lock(&wq->mutex); |
|
old_pwq = numa_pwq_tbl_install(wq, node, pwq); |
|
goto out_unlock; |
|
|
|
use_dfl_pwq: |
|
mutex_lock(&wq->mutex); |
|
raw_spin_lock_irq(&wq->dfl_pwq->pool->lock); |
|
get_pwq(wq->dfl_pwq); |
|
raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock); |
|
old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); |
|
out_unlock: |
|
mutex_unlock(&wq->mutex); |
|
put_pwq_unlocked(old_pwq); |
|
} |
|
|
|
static int alloc_and_link_pwqs(struct workqueue_struct *wq) |
|
{ |
|
bool highpri = wq->flags & WQ_HIGHPRI; |
|
int cpu, ret; |
|
|
|
if (!(wq->flags & WQ_UNBOUND)) { |
|
wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); |
|
if (!wq->cpu_pwqs) |
|
return -ENOMEM; |
|
|
|
for_each_possible_cpu(cpu) { |
|
struct pool_workqueue *pwq = |
|
per_cpu_ptr(wq->cpu_pwqs, cpu); |
|
struct worker_pool *cpu_pools = |
|
per_cpu(cpu_worker_pools, cpu); |
|
|
|
init_pwq(pwq, wq, &cpu_pools[highpri]); |
|
|
|
mutex_lock(&wq->mutex); |
|
link_pwq(pwq); |
|
mutex_unlock(&wq->mutex); |
|
} |
|
return 0; |
|
} |
|
|
|
cpus_read_lock(); |
|
if (wq->flags & __WQ_ORDERED) { |
|
ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); |
|
/* there should only be single pwq for ordering guarantee */ |
|
WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || |
|
wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), |
|
"ordering guarantee broken for workqueue %s\n", wq->name); |
|
} else { |
|
ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); |
|
} |
|
cpus_read_unlock(); |
|
|
|
return ret; |
|
} |
|
|
|
static int wq_clamp_max_active(int max_active, unsigned int flags, |
|
const char *name) |
|
{ |
|
int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
|
|
|
if (max_active < 1 || max_active > lim) |
|
pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
|
max_active, name, 1, lim); |
|
|
|
return clamp_val(max_active, 1, lim); |
|
} |
|
|
|
/* |
|
* Workqueues which may be used during memory reclaim should have a rescuer |
|
* to guarantee forward progress. |
|
*/ |
|
static int init_rescuer(struct workqueue_struct *wq) |
|
{ |
|
struct worker *rescuer; |
|
int ret; |
|
|
|
if (!(wq->flags & WQ_MEM_RECLAIM)) |
|
return 0; |
|
|
|
rescuer = alloc_worker(NUMA_NO_NODE); |
|
if (!rescuer) |
|
return -ENOMEM; |
|
|
|
rescuer->rescue_wq = wq; |
|
rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name); |
|
if (IS_ERR(rescuer->task)) { |
|
ret = PTR_ERR(rescuer->task); |
|
kfree(rescuer); |
|
return ret; |
|
} |
|
|
|
wq->rescuer = rescuer; |
|
kthread_bind_mask(rescuer->task, cpu_possible_mask); |
|
wake_up_process(rescuer->task); |
|
|
|
return 0; |
|
} |
|
|
|
__printf(1, 4) |
|
struct workqueue_struct *alloc_workqueue(const char *fmt, |
|
unsigned int flags, |
|
int max_active, ...) |
|
{ |
|
size_t tbl_size = 0; |
|
va_list args; |
|
struct workqueue_struct *wq; |
|
struct pool_workqueue *pwq; |
|
|
|
/* |
|
* Unbound && max_active == 1 used to imply ordered, which is no |
|
* longer the case on NUMA machines due to per-node pools. While |
|
* alloc_ordered_workqueue() is the right way to create an ordered |
|
* workqueue, keep the previous behavior to avoid subtle breakages |
|
* on NUMA. |
|
*/ |
|
if ((flags & WQ_UNBOUND) && max_active == 1) |
|
flags |= __WQ_ORDERED; |
|
|
|
/* see the comment above the definition of WQ_POWER_EFFICIENT */ |
|
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) |
|
flags |= WQ_UNBOUND; |
|
|
|
/* allocate wq and format name */ |
|
if (flags & WQ_UNBOUND) |
|
tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]); |
|
|
|
wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); |
|
if (!wq) |
|
return NULL; |
|
|
|
if (flags & WQ_UNBOUND) { |
|
wq->unbound_attrs = alloc_workqueue_attrs(); |
|
if (!wq->unbound_attrs) |
|
goto err_free_wq; |
|
} |
|
|
|
va_start(args, max_active); |
|
vsnprintf(wq->name, sizeof(wq->name), fmt, args); |
|
va_end(args); |
|
|
|
max_active = max_active ?: WQ_DFL_ACTIVE; |
|
max_active = wq_clamp_max_active(max_active, flags, wq->name); |
|
|
|
/* init wq */ |
|
wq->flags = flags; |
|
wq->saved_max_active = max_active; |
|
mutex_init(&wq->mutex); |
|
atomic_set(&wq->nr_pwqs_to_flush, 0); |
|
INIT_LIST_HEAD(&wq->pwqs); |
|
INIT_LIST_HEAD(&wq->flusher_queue); |
|
INIT_LIST_HEAD(&wq->flusher_overflow); |
|
INIT_LIST_HEAD(&wq->maydays); |
|
|
|
wq_init_lockdep(wq); |
|
INIT_LIST_HEAD(&wq->list); |
|
|
|
if (alloc_and_link_pwqs(wq) < 0) |
|
goto err_unreg_lockdep; |
|
|
|
if (wq_online && init_rescuer(wq) < 0) |
|
goto err_destroy; |
|
|
|
if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) |
|
goto err_destroy; |
|
|
|
/* |
|
* wq_pool_mutex protects global freeze state and workqueues list. |
|
* Grab it, adjust max_active and add the new @wq to workqueues |
|
* list. |
|
*/ |
|
mutex_lock(&wq_pool_mutex); |
|
|
|
mutex_lock(&wq->mutex); |
|
for_each_pwq(pwq, wq) |
|
pwq_adjust_max_active(pwq); |
|
mutex_unlock(&wq->mutex); |
|
|
|
list_add_tail_rcu(&wq->list, &workqueues); |
|
|
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
return wq; |
|
|
|
err_unreg_lockdep: |
|
wq_unregister_lockdep(wq); |
|
wq_free_lockdep(wq); |
|
err_free_wq: |
|
free_workqueue_attrs(wq->unbound_attrs); |
|
kfree(wq); |
|
return NULL; |
|
err_destroy: |
|
destroy_workqueue(wq); |
|
return NULL; |
|
} |
|
EXPORT_SYMBOL_GPL(alloc_workqueue); |
|
|
|
static bool pwq_busy(struct pool_workqueue *pwq) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < WORK_NR_COLORS; i++) |
|
if (pwq->nr_in_flight[i]) |
|
return true; |
|
|
|
if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) |
|
return true; |
|
if (pwq->nr_active || !list_empty(&pwq->inactive_works)) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
/** |
|
* destroy_workqueue - safely terminate a workqueue |
|
* @wq: target workqueue |
|
* |
|
* Safely destroy a workqueue. All work currently pending will be done first. |
|
*/ |
|
void destroy_workqueue(struct workqueue_struct *wq) |
|
{ |
|
struct pool_workqueue *pwq; |
|
int node; |
|
|
|
/* |
|
* Remove it from sysfs first so that sanity check failure doesn't |
|
* lead to sysfs name conflicts. |
|
*/ |
|
workqueue_sysfs_unregister(wq); |
|
|
|
/* drain it before proceeding with destruction */ |
|
drain_workqueue(wq); |
|
|
|
/* kill rescuer, if sanity checks fail, leave it w/o rescuer */ |
|
if (wq->rescuer) { |
|
struct worker *rescuer = wq->rescuer; |
|
|
|
/* this prevents new queueing */ |
|
raw_spin_lock_irq(&wq_mayday_lock); |
|
wq->rescuer = NULL; |
|
raw_spin_unlock_irq(&wq_mayday_lock); |
|
|
|
/* rescuer will empty maydays list before exiting */ |
|
kthread_stop(rescuer->task); |
|
kfree(rescuer); |
|
} |
|
|
|
/* |
|
* Sanity checks - grab all the locks so that we wait for all |
|
* in-flight operations which may do put_pwq(). |
|
*/ |
|
mutex_lock(&wq_pool_mutex); |
|
mutex_lock(&wq->mutex); |
|
for_each_pwq(pwq, wq) { |
|
raw_spin_lock_irq(&pwq->pool->lock); |
|
if (WARN_ON(pwq_busy(pwq))) { |
|
pr_warn("%s: %s has the following busy pwq\n", |
|
__func__, wq->name); |
|
show_pwq(pwq); |
|
raw_spin_unlock_irq(&pwq->pool->lock); |
|
mutex_unlock(&wq->mutex); |
|
mutex_unlock(&wq_pool_mutex); |
|
show_workqueue_state(); |
|
return; |
|
} |
|
raw_spin_unlock_irq(&pwq->pool->lock); |
|
} |
|
mutex_unlock(&wq->mutex); |
|
|
|
/* |
|
* wq list is used to freeze wq, remove from list after |
|
* flushing is complete in case freeze races us. |
|
*/ |
|
list_del_rcu(&wq->list); |
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
if (!(wq->flags & WQ_UNBOUND)) { |
|
wq_unregister_lockdep(wq); |
|
/* |
|
* The base ref is never dropped on per-cpu pwqs. Directly |
|
* schedule RCU free. |
|
*/ |
|
call_rcu(&wq->rcu, rcu_free_wq); |
|
} else { |
|
/* |
|
* We're the sole accessor of @wq at this point. Directly |
|
* access numa_pwq_tbl[] and dfl_pwq to put the base refs. |
|
* @wq will be freed when the last pwq is released. |
|
*/ |
|
for_each_node(node) { |
|
pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
|
RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); |
|
put_pwq_unlocked(pwq); |
|
} |
|
|
|
/* |
|
* Put dfl_pwq. @wq may be freed any time after dfl_pwq is |
|
* put. Don't access it afterwards. |
|
*/ |
|
pwq = wq->dfl_pwq; |
|
wq->dfl_pwq = NULL; |
|
put_pwq_unlocked(pwq); |
|
} |
|
} |
|
EXPORT_SYMBOL_GPL(destroy_workqueue); |
|
|
|
/** |
|
* workqueue_set_max_active - adjust max_active of a workqueue |
|
* @wq: target workqueue |
|
* @max_active: new max_active value. |
|
* |
|
* Set max_active of @wq to @max_active. |
|
* |
|
* CONTEXT: |
|
* Don't call from IRQ context. |
|
*/ |
|
void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
|
{ |
|
struct pool_workqueue *pwq; |
|
|
|
/* disallow meddling with max_active for ordered workqueues */ |
|
if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
|
return; |
|
|
|
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
|
|
|
mutex_lock(&wq->mutex); |
|
|
|
wq->flags &= ~__WQ_ORDERED; |
|
wq->saved_max_active = max_active; |
|
|
|
for_each_pwq(pwq, wq) |
|
pwq_adjust_max_active(pwq); |
|
|
|
mutex_unlock(&wq->mutex); |
|
} |
|
EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
|
|
|
/** |
|
* current_work - retrieve %current task's work struct |
|
* |
|
* Determine if %current task is a workqueue worker and what it's working on. |
|
* Useful to find out the context that the %current task is running in. |
|
* |
|
* Return: work struct if %current task is a workqueue worker, %NULL otherwise. |
|
*/ |
|
struct work_struct *current_work(void) |
|
{ |
|
struct worker *worker = current_wq_worker(); |
|
|
|
return worker ? worker->current_work : NULL; |
|
} |
|
EXPORT_SYMBOL(current_work); |
|
|
|
/** |
|
* current_is_workqueue_rescuer - is %current workqueue rescuer? |
|
* |
|
* Determine whether %current is a workqueue rescuer. Can be used from |
|
* work functions to determine whether it's being run off the rescuer task. |
|
* |
|
* Return: %true if %current is a workqueue rescuer. %false otherwise. |
|
*/ |
|
bool current_is_workqueue_rescuer(void) |
|
{ |
|
struct worker *worker = current_wq_worker(); |
|
|
|
return worker && worker->rescue_wq; |
|
} |
|
|
|
/** |
|
* workqueue_congested - test whether a workqueue is congested |
|
* @cpu: CPU in question |
|
* @wq: target workqueue |
|
* |
|
* Test whether @wq's cpu workqueue for @cpu is congested. There is |
|
* no synchronization around this function and the test result is |
|
* unreliable and only useful as advisory hints or for debugging. |
|
* |
|
* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. |
|
* Note that both per-cpu and unbound workqueues may be associated with |
|
* multiple pool_workqueues which have separate congested states. A |
|
* workqueue being congested on one CPU doesn't mean the workqueue is also |
|
* contested on other CPUs / NUMA nodes. |
|
* |
|
* Return: |
|
* %true if congested, %false otherwise. |
|
*/ |
|
bool workqueue_congested(int cpu, struct workqueue_struct *wq) |
|
{ |
|
struct pool_workqueue *pwq; |
|
bool ret; |
|
|
|
rcu_read_lock(); |
|
preempt_disable(); |
|
|
|
if (cpu == WORK_CPU_UNBOUND) |
|
cpu = smp_processor_id(); |
|
|
|
if (!(wq->flags & WQ_UNBOUND)) |
|
pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
|
else |
|
pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
|
|
|
ret = !list_empty(&pwq->inactive_works); |
|
preempt_enable(); |
|
rcu_read_unlock(); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(workqueue_congested); |
|
|
|
/** |
|
* work_busy - test whether a work is currently pending or running |
|
* @work: the work to be tested |
|
* |
|
* Test whether @work is currently pending or running. There is no |
|
* synchronization around this function and the test result is |
|
* unreliable and only useful as advisory hints or for debugging. |
|
* |
|
* Return: |
|
* OR'd bitmask of WORK_BUSY_* bits. |
|
*/ |
|
unsigned int work_busy(struct work_struct *work) |
|
{ |
|
struct worker_pool *pool; |
|
unsigned long flags; |
|
unsigned int ret = 0; |
|
|
|
if (work_pending(work)) |
|
ret |= WORK_BUSY_PENDING; |
|
|
|
rcu_read_lock(); |
|
pool = get_work_pool(work); |
|
if (pool) { |
|
raw_spin_lock_irqsave(&pool->lock, flags); |
|
if (find_worker_executing_work(pool, work)) |
|
ret |= WORK_BUSY_RUNNING; |
|
raw_spin_unlock_irqrestore(&pool->lock, flags); |
|
} |
|
rcu_read_unlock(); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(work_busy); |
|
|
|
/** |
|
* set_worker_desc - set description for the current work item |
|
* @fmt: printf-style format string |
|
* @...: arguments for the format string |
|
* |
|
* This function can be called by a running work function to describe what |
|
* the work item is about. If the worker task gets dumped, this |
|
* information will be printed out together to help debugging. The |
|
* description can be at most WORKER_DESC_LEN including the trailing '\0'. |
|
*/ |
|
void set_worker_desc(const char *fmt, ...) |
|
{ |
|
struct worker *worker = current_wq_worker(); |
|
va_list args; |
|
|
|
if (worker) { |
|
va_start(args, fmt); |
|
vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); |
|
va_end(args); |
|
} |
|
} |
|
EXPORT_SYMBOL_GPL(set_worker_desc); |
|
|
|
/** |
|
* print_worker_info - print out worker information and description |
|
* @log_lvl: the log level to use when printing |
|
* @task: target task |
|
* |
|
* If @task is a worker and currently executing a work item, print out the |
|
* name of the workqueue being serviced and worker description set with |
|
* set_worker_desc() by the currently executing work item. |
|
* |
|
* This function can be safely called on any task as long as the |
|
* task_struct itself is accessible. While safe, this function isn't |
|
* synchronized and may print out mixups or garbages of limited length. |
|
*/ |
|
void print_worker_info(const char *log_lvl, struct task_struct *task) |
|
{ |
|
work_func_t *fn = NULL; |
|
char name[WQ_NAME_LEN] = { }; |
|
char desc[WORKER_DESC_LEN] = { }; |
|
struct pool_workqueue *pwq = NULL; |
|
struct workqueue_struct *wq = NULL; |
|
struct worker *worker; |
|
|
|
if (!(task->flags & PF_WQ_WORKER)) |
|
return; |
|
|
|
/* |
|
* This function is called without any synchronization and @task |
|
* could be in any state. Be careful with dereferences. |
|
*/ |
|
worker = kthread_probe_data(task); |
|
|
|
/* |
|
* Carefully copy the associated workqueue's workfn, name and desc. |
|
* Keep the original last '\0' in case the original is garbage. |
|
*/ |
|
copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn)); |
|
copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq)); |
|
copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq)); |
|
copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1); |
|
copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1); |
|
|
|
if (fn || name[0] || desc[0]) { |
|
printk("%sWorkqueue: %s %ps", log_lvl, name, fn); |
|
if (strcmp(name, desc)) |
|
pr_cont(" (%s)", desc); |
|
pr_cont("\n"); |
|
} |
|
} |
|
|
|
static void pr_cont_pool_info(struct worker_pool *pool) |
|
{ |
|
pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); |
|
if (pool->node != NUMA_NO_NODE) |
|
pr_cont(" node=%d", pool->node); |
|
pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); |
|
} |
|
|
|
static void pr_cont_work(bool comma, struct work_struct *work) |
|
{ |
|
if (work->func == wq_barrier_func) { |
|
struct wq_barrier *barr; |
|
|
|
barr = container_of(work, struct wq_barrier, work); |
|
|
|
pr_cont("%s BAR(%d)", comma ? "," : "", |
|
task_pid_nr(barr->task)); |
|
} else { |
|
pr_cont("%s %ps", comma ? "," : "", work->func); |
|
} |
|
} |
|
|
|
static void show_pwq(struct pool_workqueue *pwq) |
|
{ |
|
struct worker_pool *pool = pwq->pool; |
|
struct work_struct *work; |
|
struct worker *worker; |
|
bool has_in_flight = false, has_pending = false; |
|
int bkt; |
|
|
|
pr_info(" pwq %d:", pool->id); |
|
pr_cont_pool_info(pool); |
|
|
|
pr_cont(" active=%d/%d refcnt=%d%s\n", |
|
pwq->nr_active, pwq->max_active, pwq->refcnt, |
|
!list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); |
|
|
|
hash_for_each(pool->busy_hash, bkt, worker, hentry) { |
|
if (worker->current_pwq == pwq) { |
|
has_in_flight = true; |
|
break; |
|
} |
|
} |
|
if (has_in_flight) { |
|
bool comma = false; |
|
|
|
pr_info(" in-flight:"); |
|
hash_for_each(pool->busy_hash, bkt, worker, hentry) { |
|
if (worker->current_pwq != pwq) |
|
continue; |
|
|
|
pr_cont("%s %d%s:%ps", comma ? "," : "", |
|
task_pid_nr(worker->task), |
|
worker->rescue_wq ? "(RESCUER)" : "", |
|
worker->current_func); |
|
list_for_each_entry(work, &worker->scheduled, entry) |
|
pr_cont_work(false, work); |
|
comma = true; |
|
} |
|
pr_cont("\n"); |
|
} |
|
|
|
list_for_each_entry(work, &pool->worklist, entry) { |
|
if (get_work_pwq(work) == pwq) { |
|
has_pending = true; |
|
break; |
|
} |
|
} |
|
if (has_pending) { |
|
bool comma = false; |
|
|
|
pr_info(" pending:"); |
|
list_for_each_entry(work, &pool->worklist, entry) { |
|
if (get_work_pwq(work) != pwq) |
|
continue; |
|
|
|
pr_cont_work(comma, work); |
|
comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
|
} |
|
pr_cont("\n"); |
|
} |
|
|
|
if (!list_empty(&pwq->inactive_works)) { |
|
bool comma = false; |
|
|
|
pr_info(" inactive:"); |
|
list_for_each_entry(work, &pwq->inactive_works, entry) { |
|
pr_cont_work(comma, work); |
|
comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
|
} |
|
pr_cont("\n"); |
|
} |
|
} |
|
|
|
/** |
|
* show_workqueue_state - dump workqueue state |
|
* |
|
* Called from a sysrq handler or try_to_freeze_tasks() and prints out |
|
* all busy workqueues and pools. |
|
*/ |
|
void show_workqueue_state(void) |
|
{ |
|
struct workqueue_struct *wq; |
|
struct worker_pool *pool; |
|
unsigned long flags; |
|
int pi; |
|
|
|
rcu_read_lock(); |
|
|
|
pr_info("Showing busy workqueues and worker pools:\n"); |
|
|
|
list_for_each_entry_rcu(wq, &workqueues, list) { |
|
struct pool_workqueue *pwq; |
|
bool idle = true; |
|
|
|
for_each_pwq(pwq, wq) { |
|
if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { |
|
idle = false; |
|
break; |
|
} |
|
} |
|
if (idle) |
|
continue; |
|
|
|
pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); |
|
|
|
for_each_pwq(pwq, wq) { |
|
raw_spin_lock_irqsave(&pwq->pool->lock, flags); |
|
if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { |
|
/* |
|
* Defer printing to avoid deadlocks in console |
|
* drivers that queue work while holding locks |
|
* also taken in their write paths. |
|
*/ |
|
printk_deferred_enter(); |
|
show_pwq(pwq); |
|
printk_deferred_exit(); |
|
} |
|
raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); |
|
/* |
|
* We could be printing a lot from atomic context, e.g. |
|
* sysrq-t -> show_workqueue_state(). Avoid triggering |
|
* hard lockup. |
|
*/ |
|
touch_nmi_watchdog(); |
|
} |
|
} |
|
|
|
for_each_pool(pool, pi) { |
|
struct worker *worker; |
|
bool first = true; |
|
|
|
raw_spin_lock_irqsave(&pool->lock, flags); |
|
if (pool->nr_workers == pool->nr_idle) |
|
goto next_pool; |
|
/* |
|
* Defer printing to avoid deadlocks in console drivers that |
|
* queue work while holding locks also taken in their write |
|
* paths. |
|
*/ |
|
printk_deferred_enter(); |
|
pr_info("pool %d:", pool->id); |
|
pr_cont_pool_info(pool); |
|
pr_cont(" hung=%us workers=%d", |
|
jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000, |
|
pool->nr_workers); |
|
if (pool->manager) |
|
pr_cont(" manager: %d", |
|
task_pid_nr(pool->manager->task)); |
|
list_for_each_entry(worker, &pool->idle_list, entry) { |
|
pr_cont(" %s%d", first ? "idle: " : "", |
|
task_pid_nr(worker->task)); |
|
first = false; |
|
} |
|
pr_cont("\n"); |
|
printk_deferred_exit(); |
|
next_pool: |
|
raw_spin_unlock_irqrestore(&pool->lock, flags); |
|
/* |
|
* We could be printing a lot from atomic context, e.g. |
|
* sysrq-t -> show_workqueue_state(). Avoid triggering |
|
* hard lockup. |
|
*/ |
|
touch_nmi_watchdog(); |
|
} |
|
|
|
rcu_read_unlock(); |
|
} |
|
|
|
/* used to show worker information through /proc/PID/{comm,stat,status} */ |
|
void wq_worker_comm(char *buf, size_t size, struct task_struct *task) |
|
{ |
|
int off; |
|
|
|
/* always show the actual comm */ |
|
off = strscpy(buf, task->comm, size); |
|
if (off < 0) |
|
return; |
|
|
|
/* stabilize PF_WQ_WORKER and worker pool association */ |
|
mutex_lock(&wq_pool_attach_mutex); |
|
|
|
if (task->flags & PF_WQ_WORKER) { |
|
struct worker *worker = kthread_data(task); |
|
struct worker_pool *pool = worker->pool; |
|
|
|
if (pool) { |
|
raw_spin_lock_irq(&pool->lock); |
|
/* |
|
* ->desc tracks information (wq name or |
|
* set_worker_desc()) for the latest execution. If |
|
* current, prepend '+', otherwise '-'. |
|
*/ |
|
if (worker->desc[0] != '\0') { |
|
if (worker->current_work) |
|
scnprintf(buf + off, size - off, "+%s", |
|
worker->desc); |
|
else |
|
scnprintf(buf + off, size - off, "-%s", |
|
worker->desc); |
|
} |
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
} |
|
|
|
mutex_unlock(&wq_pool_attach_mutex); |
|
} |
|
|
|
#ifdef CONFIG_SMP |
|
|
|
/* |
|
* CPU hotplug. |
|
* |
|
* There are two challenges in supporting CPU hotplug. Firstly, there |
|
* are a lot of assumptions on strong associations among work, pwq and |
|
* pool which make migrating pending and scheduled works very |
|
* difficult to implement without impacting hot paths. Secondly, |
|
* worker pools serve mix of short, long and very long running works making |
|
* blocked draining impractical. |
|
* |
|
* This is solved by allowing the pools to be disassociated from the CPU |
|
* running as an unbound one and allowing it to be reattached later if the |
|
* cpu comes back online. |
|
*/ |
|
|
|
static void unbind_workers(int cpu) |
|
{ |
|
struct worker_pool *pool; |
|
struct worker *worker; |
|
|
|
for_each_cpu_worker_pool(pool, cpu) { |
|
mutex_lock(&wq_pool_attach_mutex); |
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
/* |
|
* We've blocked all attach/detach operations. Make all workers |
|
* unbound and set DISASSOCIATED. Before this, all workers |
|
* except for the ones which are still executing works from |
|
* before the last CPU down must be on the cpu. After |
|
* this, they may become diasporas. |
|
*/ |
|
for_each_pool_worker(worker, pool) |
|
worker->flags |= WORKER_UNBOUND; |
|
|
|
pool->flags |= POOL_DISASSOCIATED; |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
|
|
for_each_pool_worker(worker, pool) { |
|
kthread_set_per_cpu(worker->task, -1); |
|
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); |
|
} |
|
|
|
mutex_unlock(&wq_pool_attach_mutex); |
|
|
|
/* |
|
* Call schedule() so that we cross rq->lock and thus can |
|
* guarantee sched callbacks see the %WORKER_UNBOUND flag. |
|
* This is necessary as scheduler callbacks may be invoked |
|
* from other cpus. |
|
*/ |
|
schedule(); |
|
|
|
/* |
|
* Sched callbacks are disabled now. Zap nr_running. |
|
* After this, nr_running stays zero and need_more_worker() |
|
* and keep_working() are always true as long as the |
|
* worklist is not empty. This pool now behaves as an |
|
* unbound (in terms of concurrency management) pool which |
|
* are served by workers tied to the pool. |
|
*/ |
|
atomic_set(&pool->nr_running, 0); |
|
|
|
/* |
|
* With concurrency management just turned off, a busy |
|
* worker blocking could lead to lengthy stalls. Kick off |
|
* unbound chain execution of currently pending work items. |
|
*/ |
|
raw_spin_lock_irq(&pool->lock); |
|
wake_up_worker(pool); |
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
} |
|
|
|
/** |
|
* rebind_workers - rebind all workers of a pool to the associated CPU |
|
* @pool: pool of interest |
|
* |
|
* @pool->cpu is coming online. Rebind all workers to the CPU. |
|
*/ |
|
static void rebind_workers(struct worker_pool *pool) |
|
{ |
|
struct worker *worker; |
|
|
|
lockdep_assert_held(&wq_pool_attach_mutex); |
|
|
|
/* |
|
* Restore CPU affinity of all workers. As all idle workers should |
|
* be on the run-queue of the associated CPU before any local |
|
* wake-ups for concurrency management happen, restore CPU affinity |
|
* of all workers first and then clear UNBOUND. As we're called |
|
* from CPU_ONLINE, the following shouldn't fail. |
|
*/ |
|
for_each_pool_worker(worker, pool) { |
|
kthread_set_per_cpu(worker->task, pool->cpu); |
|
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
|
pool->attrs->cpumask) < 0); |
|
} |
|
|
|
raw_spin_lock_irq(&pool->lock); |
|
|
|
pool->flags &= ~POOL_DISASSOCIATED; |
|
|
|
for_each_pool_worker(worker, pool) { |
|
unsigned int worker_flags = worker->flags; |
|
|
|
/* |
|
* A bound idle worker should actually be on the runqueue |
|
* of the associated CPU for local wake-ups targeting it to |
|
* work. Kick all idle workers so that they migrate to the |
|
* associated CPU. Doing this in the same loop as |
|
* replacing UNBOUND with REBOUND is safe as no worker will |
|
* be bound before @pool->lock is released. |
|
*/ |
|
if (worker_flags & WORKER_IDLE) |
|
wake_up_process(worker->task); |
|
|
|
/* |
|
* We want to clear UNBOUND but can't directly call |
|
* worker_clr_flags() or adjust nr_running. Atomically |
|
* replace UNBOUND with another NOT_RUNNING flag REBOUND. |
|
* @worker will clear REBOUND using worker_clr_flags() when |
|
* it initiates the next execution cycle thus restoring |
|
* concurrency management. Note that when or whether |
|
* @worker clears REBOUND doesn't affect correctness. |
|
* |
|
* WRITE_ONCE() is necessary because @worker->flags may be |
|
* tested without holding any lock in |
|
* wq_worker_running(). Without it, NOT_RUNNING test may |
|
* fail incorrectly leading to premature concurrency |
|
* management operations. |
|
*/ |
|
WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); |
|
worker_flags |= WORKER_REBOUND; |
|
worker_flags &= ~WORKER_UNBOUND; |
|
WRITE_ONCE(worker->flags, worker_flags); |
|
} |
|
|
|
raw_spin_unlock_irq(&pool->lock); |
|
} |
|
|
|
/** |
|
* restore_unbound_workers_cpumask - restore cpumask of unbound workers |
|
* @pool: unbound pool of interest |
|
* @cpu: the CPU which is coming up |
|
* |
|
* An unbound pool may end up with a cpumask which doesn't have any online |
|
* CPUs. When a worker of such pool get scheduled, the scheduler resets |
|
* its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any |
|
* online CPU before, cpus_allowed of all its workers should be restored. |
|
*/ |
|
static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) |
|
{ |
|
static cpumask_t cpumask; |
|
struct worker *worker; |
|
|
|
lockdep_assert_held(&wq_pool_attach_mutex); |
|
|
|
/* is @cpu allowed for @pool? */ |
|
if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) |
|
return; |
|
|
|
cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); |
|
|
|
/* as we're called from CPU_ONLINE, the following shouldn't fail */ |
|
for_each_pool_worker(worker, pool) |
|
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); |
|
} |
|
|
|
int workqueue_prepare_cpu(unsigned int cpu) |
|
{ |
|
struct worker_pool *pool; |
|
|
|
for_each_cpu_worker_pool(pool, cpu) { |
|
if (pool->nr_workers) |
|
continue; |
|
if (!create_worker(pool)) |
|
return -ENOMEM; |
|
} |
|
return 0; |
|
} |
|
|
|
int workqueue_online_cpu(unsigned int cpu) |
|
{ |
|
struct worker_pool *pool; |
|
struct workqueue_struct *wq; |
|
int pi; |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
|
|
for_each_pool(pool, pi) { |
|
mutex_lock(&wq_pool_attach_mutex); |
|
|
|
if (pool->cpu == cpu) |
|
rebind_workers(pool); |
|
else if (pool->cpu < 0) |
|
restore_unbound_workers_cpumask(pool, cpu); |
|
|
|
mutex_unlock(&wq_pool_attach_mutex); |
|
} |
|
|
|
/* update NUMA affinity of unbound workqueues */ |
|
list_for_each_entry(wq, &workqueues, list) |
|
wq_update_unbound_numa(wq, cpu, true); |
|
|
|
mutex_unlock(&wq_pool_mutex); |
|
return 0; |
|
} |
|
|
|
int workqueue_offline_cpu(unsigned int cpu) |
|
{ |
|
struct workqueue_struct *wq; |
|
|
|
/* unbinding per-cpu workers should happen on the local CPU */ |
|
if (WARN_ON(cpu != smp_processor_id())) |
|
return -1; |
|
|
|
unbind_workers(cpu); |
|
|
|
/* update NUMA affinity of unbound workqueues */ |
|
mutex_lock(&wq_pool_mutex); |
|
list_for_each_entry(wq, &workqueues, list) |
|
wq_update_unbound_numa(wq, cpu, false); |
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
return 0; |
|
} |
|
|
|
struct work_for_cpu { |
|
struct work_struct work; |
|
long (*fn)(void *); |
|
void *arg; |
|
long ret; |
|
}; |
|
|
|
static void work_for_cpu_fn(struct work_struct *work) |
|
{ |
|
struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
|
|
|
wfc->ret = wfc->fn(wfc->arg); |
|
} |
|
|
|
/** |
|
* work_on_cpu - run a function in thread context on a particular cpu |
|
* @cpu: the cpu to run on |
|
* @fn: the function to run |
|
* @arg: the function arg |
|
* |
|
* It is up to the caller to ensure that the cpu doesn't go offline. |
|
* The caller must not hold any locks which would prevent @fn from completing. |
|
* |
|
* Return: The value @fn returns. |
|
*/ |
|
long work_on_cpu(int cpu, long (*fn)(void *), void *arg) |
|
{ |
|
struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
|
|
|
INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
|
schedule_work_on(cpu, &wfc.work); |
|
flush_work(&wfc.work); |
|
destroy_work_on_stack(&wfc.work); |
|
return wfc.ret; |
|
} |
|
EXPORT_SYMBOL_GPL(work_on_cpu); |
|
|
|
/** |
|
* work_on_cpu_safe - run a function in thread context on a particular cpu |
|
* @cpu: the cpu to run on |
|
* @fn: the function to run |
|
* @arg: the function argument |
|
* |
|
* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold |
|
* any locks which would prevent @fn from completing. |
|
* |
|
* Return: The value @fn returns. |
|
*/ |
|
long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg) |
|
{ |
|
long ret = -ENODEV; |
|
|
|
cpus_read_lock(); |
|
if (cpu_online(cpu)) |
|
ret = work_on_cpu(cpu, fn, arg); |
|
cpus_read_unlock(); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(work_on_cpu_safe); |
|
#endif /* CONFIG_SMP */ |
|
|
|
#ifdef CONFIG_FREEZER |
|
|
|
/** |
|
* freeze_workqueues_begin - begin freezing workqueues |
|
* |
|
* Start freezing workqueues. After this function returns, all freezable |
|
* workqueues will queue new works to their inactive_works list instead of |
|
* pool->worklist. |
|
* |
|
* CONTEXT: |
|
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
|
*/ |
|
void freeze_workqueues_begin(void) |
|
{ |
|
struct workqueue_struct *wq; |
|
struct pool_workqueue *pwq; |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
|
|
WARN_ON_ONCE(workqueue_freezing); |
|
workqueue_freezing = true; |
|
|
|
list_for_each_entry(wq, &workqueues, list) { |
|
mutex_lock(&wq->mutex); |
|
for_each_pwq(pwq, wq) |
|
pwq_adjust_max_active(pwq); |
|
mutex_unlock(&wq->mutex); |
|
} |
|
|
|
mutex_unlock(&wq_pool_mutex); |
|
} |
|
|
|
/** |
|
* freeze_workqueues_busy - are freezable workqueues still busy? |
|
* |
|
* Check whether freezing is complete. This function must be called |
|
* between freeze_workqueues_begin() and thaw_workqueues(). |
|
* |
|
* CONTEXT: |
|
* Grabs and releases wq_pool_mutex. |
|
* |
|
* Return: |
|
* %true if some freezable workqueues are still busy. %false if freezing |
|
* is complete. |
|
*/ |
|
bool freeze_workqueues_busy(void) |
|
{ |
|
bool busy = false; |
|
struct workqueue_struct *wq; |
|
struct pool_workqueue *pwq; |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
|
|
WARN_ON_ONCE(!workqueue_freezing); |
|
|
|
list_for_each_entry(wq, &workqueues, list) { |
|
if (!(wq->flags & WQ_FREEZABLE)) |
|
continue; |
|
/* |
|
* nr_active is monotonically decreasing. It's safe |
|
* to peek without lock. |
|
*/ |
|
rcu_read_lock(); |
|
for_each_pwq(pwq, wq) { |
|
WARN_ON_ONCE(pwq->nr_active < 0); |
|
if (pwq->nr_active) { |
|
busy = true; |
|
rcu_read_unlock(); |
|
goto out_unlock; |
|
} |
|
} |
|
rcu_read_unlock(); |
|
} |
|
out_unlock: |
|
mutex_unlock(&wq_pool_mutex); |
|
return busy; |
|
} |
|
|
|
/** |
|
* thaw_workqueues - thaw workqueues |
|
* |
|
* Thaw workqueues. Normal queueing is restored and all collected |
|
* frozen works are transferred to their respective pool worklists. |
|
* |
|
* CONTEXT: |
|
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
|
*/ |
|
void thaw_workqueues(void) |
|
{ |
|
struct workqueue_struct *wq; |
|
struct pool_workqueue *pwq; |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
|
|
if (!workqueue_freezing) |
|
goto out_unlock; |
|
|
|
workqueue_freezing = false; |
|
|
|
/* restore max_active and repopulate worklist */ |
|
list_for_each_entry(wq, &workqueues, list) { |
|
mutex_lock(&wq->mutex); |
|
for_each_pwq(pwq, wq) |
|
pwq_adjust_max_active(pwq); |
|
mutex_unlock(&wq->mutex); |
|
} |
|
|
|
out_unlock: |
|
mutex_unlock(&wq_pool_mutex); |
|
} |
|
#endif /* CONFIG_FREEZER */ |
|
|
|
static int workqueue_apply_unbound_cpumask(void) |
|
{ |
|
LIST_HEAD(ctxs); |
|
int ret = 0; |
|
struct workqueue_struct *wq; |
|
struct apply_wqattrs_ctx *ctx, *n; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
list_for_each_entry(wq, &workqueues, list) { |
|
if (!(wq->flags & WQ_UNBOUND)) |
|
continue; |
|
/* creating multiple pwqs breaks ordering guarantee */ |
|
if (wq->flags & __WQ_ORDERED) |
|
continue; |
|
|
|
ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs); |
|
if (!ctx) { |
|
ret = -ENOMEM; |
|
break; |
|
} |
|
|
|
list_add_tail(&ctx->list, &ctxs); |
|
} |
|
|
|
list_for_each_entry_safe(ctx, n, &ctxs, list) { |
|
if (!ret) |
|
apply_wqattrs_commit(ctx); |
|
apply_wqattrs_cleanup(ctx); |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* workqueue_set_unbound_cpumask - Set the low-level unbound cpumask |
|
* @cpumask: the cpumask to set |
|
* |
|
* The low-level workqueues cpumask is a global cpumask that limits |
|
* the affinity of all unbound workqueues. This function check the @cpumask |
|
* and apply it to all unbound workqueues and updates all pwqs of them. |
|
* |
|
* Return: 0 - Success |
|
* -EINVAL - Invalid @cpumask |
|
* -ENOMEM - Failed to allocate memory for attrs or pwqs. |
|
*/ |
|
int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) |
|
{ |
|
int ret = -EINVAL; |
|
cpumask_var_t saved_cpumask; |
|
|
|
if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL)) |
|
return -ENOMEM; |
|
|
|
/* |
|
* Not excluding isolated cpus on purpose. |
|
* If the user wishes to include them, we allow that. |
|
*/ |
|
cpumask_and(cpumask, cpumask, cpu_possible_mask); |
|
if (!cpumask_empty(cpumask)) { |
|
apply_wqattrs_lock(); |
|
|
|
/* save the old wq_unbound_cpumask. */ |
|
cpumask_copy(saved_cpumask, wq_unbound_cpumask); |
|
|
|
/* update wq_unbound_cpumask at first and apply it to wqs. */ |
|
cpumask_copy(wq_unbound_cpumask, cpumask); |
|
ret = workqueue_apply_unbound_cpumask(); |
|
|
|
/* restore the wq_unbound_cpumask when failed. */ |
|
if (ret < 0) |
|
cpumask_copy(wq_unbound_cpumask, saved_cpumask); |
|
|
|
apply_wqattrs_unlock(); |
|
} |
|
|
|
free_cpumask_var(saved_cpumask); |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_SYSFS |
|
/* |
|
* Workqueues with WQ_SYSFS flag set is visible to userland via |
|
* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the |
|
* following attributes. |
|
* |
|
* per_cpu RO bool : whether the workqueue is per-cpu or unbound |
|
* max_active RW int : maximum number of in-flight work items |
|
* |
|
* Unbound workqueues have the following extra attributes. |
|
* |
|
* pool_ids RO int : the associated pool IDs for each node |
|
* nice RW int : nice value of the workers |
|
* cpumask RW mask : bitmask of allowed CPUs for the workers |
|
* numa RW bool : whether enable NUMA affinity |
|
*/ |
|
struct wq_device { |
|
struct workqueue_struct *wq; |
|
struct device dev; |
|
}; |
|
|
|
static struct workqueue_struct *dev_to_wq(struct device *dev) |
|
{ |
|
struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
|
|
|
return wq_dev->wq; |
|
} |
|
|
|
static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, |
|
char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
|
|
return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); |
|
} |
|
static DEVICE_ATTR_RO(per_cpu); |
|
|
|
static ssize_t max_active_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
|
|
return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); |
|
} |
|
|
|
static ssize_t max_active_store(struct device *dev, |
|
struct device_attribute *attr, const char *buf, |
|
size_t count) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
int val; |
|
|
|
if (sscanf(buf, "%d", &val) != 1 || val <= 0) |
|
return -EINVAL; |
|
|
|
workqueue_set_max_active(wq, val); |
|
return count; |
|
} |
|
static DEVICE_ATTR_RW(max_active); |
|
|
|
static struct attribute *wq_sysfs_attrs[] = { |
|
&dev_attr_per_cpu.attr, |
|
&dev_attr_max_active.attr, |
|
NULL, |
|
}; |
|
ATTRIBUTE_GROUPS(wq_sysfs); |
|
|
|
static ssize_t wq_pool_ids_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
const char *delim = ""; |
|
int node, written = 0; |
|
|
|
cpus_read_lock(); |
|
rcu_read_lock(); |
|
for_each_node(node) { |
|
written += scnprintf(buf + written, PAGE_SIZE - written, |
|
"%s%d:%d", delim, node, |
|
unbound_pwq_by_node(wq, node)->pool->id); |
|
delim = " "; |
|
} |
|
written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); |
|
rcu_read_unlock(); |
|
cpus_read_unlock(); |
|
|
|
return written; |
|
} |
|
|
|
static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, |
|
char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
int written; |
|
|
|
mutex_lock(&wq->mutex); |
|
written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); |
|
mutex_unlock(&wq->mutex); |
|
|
|
return written; |
|
} |
|
|
|
/* prepare workqueue_attrs for sysfs store operations */ |
|
static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) |
|
{ |
|
struct workqueue_attrs *attrs; |
|
|
|
lockdep_assert_held(&wq_pool_mutex); |
|
|
|
attrs = alloc_workqueue_attrs(); |
|
if (!attrs) |
|
return NULL; |
|
|
|
copy_workqueue_attrs(attrs, wq->unbound_attrs); |
|
return attrs; |
|
} |
|
|
|
static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
struct workqueue_attrs *attrs; |
|
int ret = -ENOMEM; |
|
|
|
apply_wqattrs_lock(); |
|
|
|
attrs = wq_sysfs_prep_attrs(wq); |
|
if (!attrs) |
|
goto out_unlock; |
|
|
|
if (sscanf(buf, "%d", &attrs->nice) == 1 && |
|
attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) |
|
ret = apply_workqueue_attrs_locked(wq, attrs); |
|
else |
|
ret = -EINVAL; |
|
|
|
out_unlock: |
|
apply_wqattrs_unlock(); |
|
free_workqueue_attrs(attrs); |
|
return ret ?: count; |
|
} |
|
|
|
static ssize_t wq_cpumask_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
int written; |
|
|
|
mutex_lock(&wq->mutex); |
|
written = scnprintf(buf, PAGE_SIZE, "%*pb\n", |
|
cpumask_pr_args(wq->unbound_attrs->cpumask)); |
|
mutex_unlock(&wq->mutex); |
|
return written; |
|
} |
|
|
|
static ssize_t wq_cpumask_store(struct device *dev, |
|
struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
struct workqueue_attrs *attrs; |
|
int ret = -ENOMEM; |
|
|
|
apply_wqattrs_lock(); |
|
|
|
attrs = wq_sysfs_prep_attrs(wq); |
|
if (!attrs) |
|
goto out_unlock; |
|
|
|
ret = cpumask_parse(buf, attrs->cpumask); |
|
if (!ret) |
|
ret = apply_workqueue_attrs_locked(wq, attrs); |
|
|
|
out_unlock: |
|
apply_wqattrs_unlock(); |
|
free_workqueue_attrs(attrs); |
|
return ret ?: count; |
|
} |
|
|
|
static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, |
|
char *buf) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
int written; |
|
|
|
mutex_lock(&wq->mutex); |
|
written = scnprintf(buf, PAGE_SIZE, "%d\n", |
|
!wq->unbound_attrs->no_numa); |
|
mutex_unlock(&wq->mutex); |
|
|
|
return written; |
|
} |
|
|
|
static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
struct workqueue_struct *wq = dev_to_wq(dev); |
|
struct workqueue_attrs *attrs; |
|
int v, ret = -ENOMEM; |
|
|
|
apply_wqattrs_lock(); |
|
|
|
attrs = wq_sysfs_prep_attrs(wq); |
|
if (!attrs) |
|
goto out_unlock; |
|
|
|
ret = -EINVAL; |
|
if (sscanf(buf, "%d", &v) == 1) { |
|
attrs->no_numa = !v; |
|
ret = apply_workqueue_attrs_locked(wq, attrs); |
|
} |
|
|
|
out_unlock: |
|
apply_wqattrs_unlock(); |
|
free_workqueue_attrs(attrs); |
|
return ret ?: count; |
|
} |
|
|
|
static struct device_attribute wq_sysfs_unbound_attrs[] = { |
|
__ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), |
|
__ATTR(nice, 0644, wq_nice_show, wq_nice_store), |
|
__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), |
|
__ATTR(numa, 0644, wq_numa_show, wq_numa_store), |
|
__ATTR_NULL, |
|
}; |
|
|
|
static struct bus_type wq_subsys = { |
|
.name = "workqueue", |
|
.dev_groups = wq_sysfs_groups, |
|
}; |
|
|
|
static ssize_t wq_unbound_cpumask_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
int written; |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
written = scnprintf(buf, PAGE_SIZE, "%*pb\n", |
|
cpumask_pr_args(wq_unbound_cpumask)); |
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
return written; |
|
} |
|
|
|
static ssize_t wq_unbound_cpumask_store(struct device *dev, |
|
struct device_attribute *attr, const char *buf, size_t count) |
|
{ |
|
cpumask_var_t cpumask; |
|
int ret; |
|
|
|
if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) |
|
return -ENOMEM; |
|
|
|
ret = cpumask_parse(buf, cpumask); |
|
if (!ret) |
|
ret = workqueue_set_unbound_cpumask(cpumask); |
|
|
|
free_cpumask_var(cpumask); |
|
return ret ? ret : count; |
|
} |
|
|
|
static struct device_attribute wq_sysfs_cpumask_attr = |
|
__ATTR(cpumask, 0644, wq_unbound_cpumask_show, |
|
wq_unbound_cpumask_store); |
|
|
|
static int __init wq_sysfs_init(void) |
|
{ |
|
int err; |
|
|
|
err = subsys_virtual_register(&wq_subsys, NULL); |
|
if (err) |
|
return err; |
|
|
|
return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr); |
|
} |
|
core_initcall(wq_sysfs_init); |
|
|
|
static void wq_device_release(struct device *dev) |
|
{ |
|
struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
|
|
|
kfree(wq_dev); |
|
} |
|
|
|
/** |
|
* workqueue_sysfs_register - make a workqueue visible in sysfs |
|
* @wq: the workqueue to register |
|
* |
|
* Expose @wq in sysfs under /sys/bus/workqueue/devices. |
|
* alloc_workqueue*() automatically calls this function if WQ_SYSFS is set |
|
* which is the preferred method. |
|
* |
|
* Workqueue user should use this function directly iff it wants to apply |
|
* workqueue_attrs before making the workqueue visible in sysfs; otherwise, |
|
* apply_workqueue_attrs() may race against userland updating the |
|
* attributes. |
|
* |
|
* Return: 0 on success, -errno on failure. |
|
*/ |
|
int workqueue_sysfs_register(struct workqueue_struct *wq) |
|
{ |
|
struct wq_device *wq_dev; |
|
int ret; |
|
|
|
/* |
|
* Adjusting max_active or creating new pwqs by applying |
|
* attributes breaks ordering guarantee. Disallow exposing ordered |
|
* workqueues. |
|
*/ |
|
if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
|
return -EINVAL; |
|
|
|
wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); |
|
if (!wq_dev) |
|
return -ENOMEM; |
|
|
|
wq_dev->wq = wq; |
|
wq_dev->dev.bus = &wq_subsys; |
|
wq_dev->dev.release = wq_device_release; |
|
dev_set_name(&wq_dev->dev, "%s", wq->name); |
|
|
|
/* |
|
* unbound_attrs are created separately. Suppress uevent until |
|
* everything is ready. |
|
*/ |
|
dev_set_uevent_suppress(&wq_dev->dev, true); |
|
|
|
ret = device_register(&wq_dev->dev); |
|
if (ret) { |
|
put_device(&wq_dev->dev); |
|
wq->wq_dev = NULL; |
|
return ret; |
|
} |
|
|
|
if (wq->flags & WQ_UNBOUND) { |
|
struct device_attribute *attr; |
|
|
|
for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { |
|
ret = device_create_file(&wq_dev->dev, attr); |
|
if (ret) { |
|
device_unregister(&wq_dev->dev); |
|
wq->wq_dev = NULL; |
|
return ret; |
|
} |
|
} |
|
} |
|
|
|
dev_set_uevent_suppress(&wq_dev->dev, false); |
|
kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); |
|
return 0; |
|
} |
|
|
|
/** |
|
* workqueue_sysfs_unregister - undo workqueue_sysfs_register() |
|
* @wq: the workqueue to unregister |
|
* |
|
* If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. |
|
*/ |
|
static void workqueue_sysfs_unregister(struct workqueue_struct *wq) |
|
{ |
|
struct wq_device *wq_dev = wq->wq_dev; |
|
|
|
if (!wq->wq_dev) |
|
return; |
|
|
|
wq->wq_dev = NULL; |
|
device_unregister(&wq_dev->dev); |
|
} |
|
#else /* CONFIG_SYSFS */ |
|
static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } |
|
#endif /* CONFIG_SYSFS */ |
|
|
|
/* |
|
* Workqueue watchdog. |
|
* |
|
* Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal |
|
* flush dependency, a concurrency managed work item which stays RUNNING |
|
* indefinitely. Workqueue stalls can be very difficult to debug as the |
|
* usual warning mechanisms don't trigger and internal workqueue state is |
|
* largely opaque. |
|
* |
|
* Workqueue watchdog monitors all worker pools periodically and dumps |
|
* state if some pools failed to make forward progress for a while where |
|
* forward progress is defined as the first item on ->worklist changing. |
|
* |
|
* This mechanism is controlled through the kernel parameter |
|
* "workqueue.watchdog_thresh" which can be updated at runtime through the |
|
* corresponding sysfs parameter file. |
|
*/ |
|
#ifdef CONFIG_WQ_WATCHDOG |
|
|
|
static unsigned long wq_watchdog_thresh = 30; |
|
static struct timer_list wq_watchdog_timer; |
|
|
|
static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; |
|
static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; |
|
|
|
static void wq_watchdog_reset_touched(void) |
|
{ |
|
int cpu; |
|
|
|
wq_watchdog_touched = jiffies; |
|
for_each_possible_cpu(cpu) |
|
per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; |
|
} |
|
|
|
static void wq_watchdog_timer_fn(struct timer_list *unused) |
|
{ |
|
unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; |
|
bool lockup_detected = false; |
|
unsigned long now = jiffies; |
|
struct worker_pool *pool; |
|
int pi; |
|
|
|
if (!thresh) |
|
return; |
|
|
|
rcu_read_lock(); |
|
|
|
for_each_pool(pool, pi) { |
|
unsigned long pool_ts, touched, ts; |
|
|
|
if (list_empty(&pool->worklist)) |
|
continue; |
|
|
|
/* |
|
* If a virtual machine is stopped by the host it can look to |
|
* the watchdog like a stall. |
|
*/ |
|
kvm_check_and_clear_guest_paused(); |
|
|
|
/* get the latest of pool and touched timestamps */ |
|
if (pool->cpu >= 0) |
|
touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); |
|
else |
|
touched = READ_ONCE(wq_watchdog_touched); |
|
pool_ts = READ_ONCE(pool->watchdog_ts); |
|
|
|
if (time_after(pool_ts, touched)) |
|
ts = pool_ts; |
|
else |
|
ts = touched; |
|
|
|
/* did we stall? */ |
|
if (time_after(now, ts + thresh)) { |
|
lockup_detected = true; |
|
pr_emerg("BUG: workqueue lockup - pool"); |
|
pr_cont_pool_info(pool); |
|
pr_cont(" stuck for %us!\n", |
|
jiffies_to_msecs(now - pool_ts) / 1000); |
|
} |
|
} |
|
|
|
rcu_read_unlock(); |
|
|
|
if (lockup_detected) |
|
show_workqueue_state(); |
|
|
|
wq_watchdog_reset_touched(); |
|
mod_timer(&wq_watchdog_timer, jiffies + thresh); |
|
} |
|
|
|
notrace void wq_watchdog_touch(int cpu) |
|
{ |
|
if (cpu >= 0) |
|
per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; |
|
|
|
wq_watchdog_touched = jiffies; |
|
} |
|
|
|
static void wq_watchdog_set_thresh(unsigned long thresh) |
|
{ |
|
wq_watchdog_thresh = 0; |
|
del_timer_sync(&wq_watchdog_timer); |
|
|
|
if (thresh) { |
|
wq_watchdog_thresh = thresh; |
|
wq_watchdog_reset_touched(); |
|
mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); |
|
} |
|
} |
|
|
|
static int wq_watchdog_param_set_thresh(const char *val, |
|
const struct kernel_param *kp) |
|
{ |
|
unsigned long thresh; |
|
int ret; |
|
|
|
ret = kstrtoul(val, 0, &thresh); |
|
if (ret) |
|
return ret; |
|
|
|
if (system_wq) |
|
wq_watchdog_set_thresh(thresh); |
|
else |
|
wq_watchdog_thresh = thresh; |
|
|
|
return 0; |
|
} |
|
|
|
static const struct kernel_param_ops wq_watchdog_thresh_ops = { |
|
.set = wq_watchdog_param_set_thresh, |
|
.get = param_get_ulong, |
|
}; |
|
|
|
module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, |
|
0644); |
|
|
|
static void wq_watchdog_init(void) |
|
{ |
|
timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); |
|
wq_watchdog_set_thresh(wq_watchdog_thresh); |
|
} |
|
|
|
#else /* CONFIG_WQ_WATCHDOG */ |
|
|
|
static inline void wq_watchdog_init(void) { } |
|
|
|
#endif /* CONFIG_WQ_WATCHDOG */ |
|
|
|
static void __init wq_numa_init(void) |
|
{ |
|
cpumask_var_t *tbl; |
|
int node, cpu; |
|
|
|
if (num_possible_nodes() <= 1) |
|
return; |
|
|
|
if (wq_disable_numa) { |
|
pr_info("workqueue: NUMA affinity support disabled\n"); |
|
return; |
|
} |
|
|
|
for_each_possible_cpu(cpu) { |
|
if (WARN_ON(cpu_to_node(cpu) == NUMA_NO_NODE)) { |
|
pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); |
|
return; |
|
} |
|
} |
|
|
|
wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(); |
|
BUG_ON(!wq_update_unbound_numa_attrs_buf); |
|
|
|
/* |
|
* We want masks of possible CPUs of each node which isn't readily |
|
* available. Build one from cpu_to_node() which should have been |
|
* fully initialized by now. |
|
*/ |
|
tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL); |
|
BUG_ON(!tbl); |
|
|
|
for_each_node(node) |
|
BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, |
|
node_online(node) ? node : NUMA_NO_NODE)); |
|
|
|
for_each_possible_cpu(cpu) { |
|
node = cpu_to_node(cpu); |
|
cpumask_set_cpu(cpu, tbl[node]); |
|
} |
|
|
|
wq_numa_possible_cpumask = tbl; |
|
wq_numa_enabled = true; |
|
} |
|
|
|
/** |
|
* workqueue_init_early - early init for workqueue subsystem |
|
* |
|
* This is the first half of two-staged workqueue subsystem initialization |
|
* and invoked as soon as the bare basics - memory allocation, cpumasks and |
|
* idr are up. It sets up all the data structures and system workqueues |
|
* and allows early boot code to create workqueues and queue/cancel work |
|
* items. Actual work item execution starts only after kthreads can be |
|
* created and scheduled right before early initcalls. |
|
*/ |
|
void __init workqueue_init_early(void) |
|
{ |
|
int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; |
|
int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; |
|
int i, cpu; |
|
|
|
BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); |
|
|
|
BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); |
|
cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags)); |
|
|
|
pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); |
|
|
|
/* initialize CPU pools */ |
|
for_each_possible_cpu(cpu) { |
|
struct worker_pool *pool; |
|
|
|
i = 0; |
|
for_each_cpu_worker_pool(pool, cpu) { |
|
BUG_ON(init_worker_pool(pool)); |
|
pool->cpu = cpu; |
|
cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); |
|
pool->attrs->nice = std_nice[i++]; |
|
pool->node = cpu_to_node(cpu); |
|
|
|
/* alloc pool ID */ |
|
mutex_lock(&wq_pool_mutex); |
|
BUG_ON(worker_pool_assign_id(pool)); |
|
mutex_unlock(&wq_pool_mutex); |
|
} |
|
} |
|
|
|
/* create default unbound and ordered wq attrs */ |
|
for (i = 0; i < NR_STD_WORKER_POOLS; i++) { |
|
struct workqueue_attrs *attrs; |
|
|
|
BUG_ON(!(attrs = alloc_workqueue_attrs())); |
|
attrs->nice = std_nice[i]; |
|
unbound_std_wq_attrs[i] = attrs; |
|
|
|
/* |
|
* An ordered wq should have only one pwq as ordering is |
|
* guaranteed by max_active which is enforced by pwqs. |
|
* Turn off NUMA so that dfl_pwq is used for all nodes. |
|
*/ |
|
BUG_ON(!(attrs = alloc_workqueue_attrs())); |
|
attrs->nice = std_nice[i]; |
|
attrs->no_numa = true; |
|
ordered_wq_attrs[i] = attrs; |
|
} |
|
|
|
system_wq = alloc_workqueue("events", 0, 0); |
|
system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
|
system_long_wq = alloc_workqueue("events_long", 0, 0); |
|
system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
|
WQ_UNBOUND_MAX_ACTIVE); |
|
system_freezable_wq = alloc_workqueue("events_freezable", |
|
WQ_FREEZABLE, 0); |
|
system_power_efficient_wq = alloc_workqueue("events_power_efficient", |
|
WQ_POWER_EFFICIENT, 0); |
|
system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", |
|
WQ_FREEZABLE | WQ_POWER_EFFICIENT, |
|
0); |
|
BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
|
!system_unbound_wq || !system_freezable_wq || |
|
!system_power_efficient_wq || |
|
!system_freezable_power_efficient_wq); |
|
} |
|
|
|
/** |
|
* workqueue_init - bring workqueue subsystem fully online |
|
* |
|
* This is the latter half of two-staged workqueue subsystem initialization |
|
* and invoked as soon as kthreads can be created and scheduled. |
|
* Workqueues have been created and work items queued on them, but there |
|
* are no kworkers executing the work items yet. Populate the worker pools |
|
* with the initial workers and enable future kworker creations. |
|
*/ |
|
void __init workqueue_init(void) |
|
{ |
|
struct workqueue_struct *wq; |
|
struct worker_pool *pool; |
|
int cpu, bkt; |
|
|
|
/* |
|
* It'd be simpler to initialize NUMA in workqueue_init_early() but |
|
* CPU to node mapping may not be available that early on some |
|
* archs such as power and arm64. As per-cpu pools created |
|
* previously could be missing node hint and unbound pools NUMA |
|
* affinity, fix them up. |
|
* |
|
* Also, while iterating workqueues, create rescuers if requested. |
|
*/ |
|
wq_numa_init(); |
|
|
|
mutex_lock(&wq_pool_mutex); |
|
|
|
for_each_possible_cpu(cpu) { |
|
for_each_cpu_worker_pool(pool, cpu) { |
|
pool->node = cpu_to_node(cpu); |
|
} |
|
} |
|
|
|
list_for_each_entry(wq, &workqueues, list) { |
|
wq_update_unbound_numa(wq, smp_processor_id(), true); |
|
WARN(init_rescuer(wq), |
|
"workqueue: failed to create early rescuer for %s", |
|
wq->name); |
|
} |
|
|
|
mutex_unlock(&wq_pool_mutex); |
|
|
|
/* create the initial workers */ |
|
for_each_online_cpu(cpu) { |
|
for_each_cpu_worker_pool(pool, cpu) { |
|
pool->flags &= ~POOL_DISASSOCIATED; |
|
BUG_ON(!create_worker(pool)); |
|
} |
|
} |
|
|
|
hash_for_each(unbound_pool_hash, bkt, pool, hash_node) |
|
BUG_ON(!create_worker(pool)); |
|
|
|
wq_online = true; |
|
wq_watchdog_init(); |
|
}
|
|
|