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1470 lines
40 KiB
1470 lines
40 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* Kernel thread helper functions. |
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* Copyright (C) 2004 IBM Corporation, Rusty Russell. |
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* Copyright (C) 2009 Red Hat, Inc. |
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* |
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* Creation is done via kthreadd, so that we get a clean environment |
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* even if we're invoked from userspace (think modprobe, hotplug cpu, |
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* etc.). |
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*/ |
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#include <uapi/linux/sched/types.h> |
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#include <linux/mm.h> |
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#include <linux/mmu_context.h> |
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#include <linux/sched.h> |
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#include <linux/sched/mm.h> |
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#include <linux/sched/task.h> |
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#include <linux/kthread.h> |
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#include <linux/completion.h> |
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#include <linux/err.h> |
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#include <linux/cgroup.h> |
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#include <linux/cpuset.h> |
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#include <linux/unistd.h> |
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#include <linux/file.h> |
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#include <linux/export.h> |
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#include <linux/mutex.h> |
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#include <linux/slab.h> |
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#include <linux/freezer.h> |
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#include <linux/ptrace.h> |
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#include <linux/uaccess.h> |
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#include <linux/numa.h> |
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#include <linux/sched/isolation.h> |
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#include <trace/events/sched.h> |
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static DEFINE_SPINLOCK(kthread_create_lock); |
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static LIST_HEAD(kthread_create_list); |
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struct task_struct *kthreadd_task; |
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struct kthread_create_info |
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{ |
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/* Information passed to kthread() from kthreadd. */ |
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int (*threadfn)(void *data); |
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void *data; |
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int node; |
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/* Result passed back to kthread_create() from kthreadd. */ |
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struct task_struct *result; |
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struct completion *done; |
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struct list_head list; |
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}; |
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struct kthread { |
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unsigned long flags; |
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unsigned int cpu; |
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int (*threadfn)(void *); |
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void *data; |
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mm_segment_t oldfs; |
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struct completion parked; |
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struct completion exited; |
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#ifdef CONFIG_BLK_CGROUP |
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struct cgroup_subsys_state *blkcg_css; |
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#endif |
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}; |
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enum KTHREAD_BITS { |
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KTHREAD_IS_PER_CPU = 0, |
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KTHREAD_SHOULD_STOP, |
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KTHREAD_SHOULD_PARK, |
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}; |
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|
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static inline struct kthread *to_kthread(struct task_struct *k) |
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{ |
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WARN_ON(!(k->flags & PF_KTHREAD)); |
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return (__force void *)k->set_child_tid; |
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} |
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|
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/* |
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* Variant of to_kthread() that doesn't assume @p is a kthread. |
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* |
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* Per construction; when: |
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* |
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* (p->flags & PF_KTHREAD) && p->set_child_tid |
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* |
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* the task is both a kthread and struct kthread is persistent. However |
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* PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and |
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* begin_new_exec()). |
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*/ |
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static inline struct kthread *__to_kthread(struct task_struct *p) |
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{ |
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void *kthread = (__force void *)p->set_child_tid; |
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if (kthread && !(p->flags & PF_KTHREAD)) |
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kthread = NULL; |
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return kthread; |
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} |
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void set_kthread_struct(struct task_struct *p) |
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{ |
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struct kthread *kthread; |
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|
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if (__to_kthread(p)) |
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return; |
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kthread = kzalloc(sizeof(*kthread), GFP_KERNEL); |
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/* |
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* We abuse ->set_child_tid to avoid the new member and because it |
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* can't be wrongly copied by copy_process(). We also rely on fact |
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* that the caller can't exec, so PF_KTHREAD can't be cleared. |
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*/ |
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p->set_child_tid = (__force void __user *)kthread; |
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} |
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void free_kthread_struct(struct task_struct *k) |
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{ |
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struct kthread *kthread; |
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|
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/* |
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* Can be NULL if this kthread was created by kernel_thread() |
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* or if kmalloc() in kthread() failed. |
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*/ |
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kthread = to_kthread(k); |
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#ifdef CONFIG_BLK_CGROUP |
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WARN_ON_ONCE(kthread && kthread->blkcg_css); |
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#endif |
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kfree(kthread); |
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} |
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/** |
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* kthread_should_stop - should this kthread return now? |
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* |
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* When someone calls kthread_stop() on your kthread, it will be woken |
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* and this will return true. You should then return, and your return |
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* value will be passed through to kthread_stop(). |
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*/ |
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bool kthread_should_stop(void) |
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{ |
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return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
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} |
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EXPORT_SYMBOL(kthread_should_stop); |
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bool __kthread_should_park(struct task_struct *k) |
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{ |
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return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); |
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} |
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EXPORT_SYMBOL_GPL(__kthread_should_park); |
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|
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/** |
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* kthread_should_park - should this kthread park now? |
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* |
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* When someone calls kthread_park() on your kthread, it will be woken |
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* and this will return true. You should then do the necessary |
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* cleanup and call kthread_parkme() |
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* |
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* Similar to kthread_should_stop(), but this keeps the thread alive |
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* and in a park position. kthread_unpark() "restarts" the thread and |
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* calls the thread function again. |
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*/ |
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bool kthread_should_park(void) |
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{ |
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return __kthread_should_park(current); |
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} |
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EXPORT_SYMBOL_GPL(kthread_should_park); |
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|
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/** |
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* kthread_freezable_should_stop - should this freezable kthread return now? |
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* @was_frozen: optional out parameter, indicates whether %current was frozen |
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* |
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* kthread_should_stop() for freezable kthreads, which will enter |
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* refrigerator if necessary. This function is safe from kthread_stop() / |
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* freezer deadlock and freezable kthreads should use this function instead |
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* of calling try_to_freeze() directly. |
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*/ |
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bool kthread_freezable_should_stop(bool *was_frozen) |
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{ |
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bool frozen = false; |
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might_sleep(); |
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if (unlikely(freezing(current))) |
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frozen = __refrigerator(true); |
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if (was_frozen) |
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*was_frozen = frozen; |
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return kthread_should_stop(); |
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} |
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EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); |
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/** |
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* kthread_func - return the function specified on kthread creation |
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* @task: kthread task in question |
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* |
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* Returns NULL if the task is not a kthread. |
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*/ |
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void *kthread_func(struct task_struct *task) |
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{ |
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struct kthread *kthread = __to_kthread(task); |
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if (kthread) |
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return kthread->threadfn; |
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return NULL; |
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} |
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EXPORT_SYMBOL_GPL(kthread_func); |
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|
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/** |
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* kthread_data - return data value specified on kthread creation |
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* @task: kthread task in question |
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* |
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* Return the data value specified when kthread @task was created. |
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* The caller is responsible for ensuring the validity of @task when |
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* calling this function. |
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*/ |
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void *kthread_data(struct task_struct *task) |
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{ |
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return to_kthread(task)->data; |
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} |
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EXPORT_SYMBOL_GPL(kthread_data); |
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|
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/** |
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* kthread_probe_data - speculative version of kthread_data() |
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* @task: possible kthread task in question |
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* |
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* @task could be a kthread task. Return the data value specified when it |
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* was created if accessible. If @task isn't a kthread task or its data is |
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* inaccessible for any reason, %NULL is returned. This function requires |
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* that @task itself is safe to dereference. |
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*/ |
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void *kthread_probe_data(struct task_struct *task) |
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{ |
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struct kthread *kthread = __to_kthread(task); |
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void *data = NULL; |
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if (kthread) |
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copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); |
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return data; |
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} |
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static void __kthread_parkme(struct kthread *self) |
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{ |
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for (;;) { |
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/* |
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* TASK_PARKED is a special state; we must serialize against |
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* possible pending wakeups to avoid store-store collisions on |
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* task->state. |
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* |
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* Such a collision might possibly result in the task state |
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* changin from TASK_PARKED and us failing the |
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* wait_task_inactive() in kthread_park(). |
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*/ |
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set_special_state(TASK_PARKED); |
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if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
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break; |
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/* |
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* Thread is going to call schedule(), do not preempt it, |
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* or the caller of kthread_park() may spend more time in |
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* wait_task_inactive(). |
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*/ |
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preempt_disable(); |
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complete(&self->parked); |
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schedule_preempt_disabled(); |
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preempt_enable(); |
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} |
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__set_current_state(TASK_RUNNING); |
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} |
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void kthread_parkme(void) |
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{ |
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__kthread_parkme(to_kthread(current)); |
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} |
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EXPORT_SYMBOL_GPL(kthread_parkme); |
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static int kthread(void *_create) |
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{ |
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/* Copy data: it's on kthread's stack */ |
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struct kthread_create_info *create = _create; |
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int (*threadfn)(void *data) = create->threadfn; |
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void *data = create->data; |
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struct completion *done; |
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struct kthread *self; |
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int ret; |
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set_kthread_struct(current); |
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self = to_kthread(current); |
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/* If user was SIGKILLed, I release the structure. */ |
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done = xchg(&create->done, NULL); |
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if (!done) { |
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kfree(create); |
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do_exit(-EINTR); |
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} |
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if (!self) { |
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create->result = ERR_PTR(-ENOMEM); |
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complete(done); |
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do_exit(-ENOMEM); |
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} |
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self->threadfn = threadfn; |
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self->data = data; |
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init_completion(&self->exited); |
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init_completion(&self->parked); |
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current->vfork_done = &self->exited; |
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|
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/* OK, tell user we're spawned, wait for stop or wakeup */ |
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__set_current_state(TASK_UNINTERRUPTIBLE); |
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create->result = current; |
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/* |
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* Thread is going to call schedule(), do not preempt it, |
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* or the creator may spend more time in wait_task_inactive(). |
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*/ |
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preempt_disable(); |
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complete(done); |
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schedule_preempt_disabled(); |
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preempt_enable(); |
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ret = -EINTR; |
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if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
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cgroup_kthread_ready(); |
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__kthread_parkme(self); |
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ret = threadfn(data); |
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} |
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do_exit(ret); |
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} |
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/* called from kernel_clone() to get node information for about to be created task */ |
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int tsk_fork_get_node(struct task_struct *tsk) |
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{ |
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#ifdef CONFIG_NUMA |
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if (tsk == kthreadd_task) |
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return tsk->pref_node_fork; |
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#endif |
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return NUMA_NO_NODE; |
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} |
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static void create_kthread(struct kthread_create_info *create) |
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{ |
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int pid; |
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#ifdef CONFIG_NUMA |
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current->pref_node_fork = create->node; |
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#endif |
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/* We want our own signal handler (we take no signals by default). */ |
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pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); |
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if (pid < 0) { |
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/* If user was SIGKILLed, I release the structure. */ |
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struct completion *done = xchg(&create->done, NULL); |
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if (!done) { |
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kfree(create); |
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return; |
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} |
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create->result = ERR_PTR(pid); |
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complete(done); |
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} |
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} |
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static __printf(4, 0) |
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struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), |
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void *data, int node, |
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const char namefmt[], |
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va_list args) |
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{ |
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DECLARE_COMPLETION_ONSTACK(done); |
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struct task_struct *task; |
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struct kthread_create_info *create = kmalloc(sizeof(*create), |
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GFP_KERNEL); |
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if (!create) |
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return ERR_PTR(-ENOMEM); |
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create->threadfn = threadfn; |
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create->data = data; |
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create->node = node; |
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create->done = &done; |
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spin_lock(&kthread_create_lock); |
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list_add_tail(&create->list, &kthread_create_list); |
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spin_unlock(&kthread_create_lock); |
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wake_up_process(kthreadd_task); |
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/* |
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* Wait for completion in killable state, for I might be chosen by |
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* the OOM killer while kthreadd is trying to allocate memory for |
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* new kernel thread. |
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*/ |
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if (unlikely(wait_for_completion_killable(&done))) { |
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/* |
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* If I was SIGKILLed before kthreadd (or new kernel thread) |
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* calls complete(), leave the cleanup of this structure to |
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* that thread. |
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*/ |
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if (xchg(&create->done, NULL)) |
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return ERR_PTR(-EINTR); |
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/* |
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* kthreadd (or new kernel thread) will call complete() |
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* shortly. |
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*/ |
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wait_for_completion(&done); |
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} |
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task = create->result; |
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if (!IS_ERR(task)) { |
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static const struct sched_param param = { .sched_priority = 0 }; |
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char name[TASK_COMM_LEN]; |
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/* |
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* task is already visible to other tasks, so updating |
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* COMM must be protected. |
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*/ |
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vsnprintf(name, sizeof(name), namefmt, args); |
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set_task_comm(task, name); |
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/* |
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* root may have changed our (kthreadd's) priority or CPU mask. |
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* The kernel thread should not inherit these properties. |
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*/ |
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sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
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set_cpus_allowed_ptr(task, |
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housekeeping_cpumask(HK_FLAG_KTHREAD)); |
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} |
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kfree(create); |
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return task; |
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} |
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|
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/** |
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* kthread_create_on_node - create a kthread. |
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* @threadfn: the function to run until signal_pending(current). |
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* @data: data ptr for @threadfn. |
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* @node: task and thread structures for the thread are allocated on this node |
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* @namefmt: printf-style name for the thread. |
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* |
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* Description: This helper function creates and names a kernel |
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* thread. The thread will be stopped: use wake_up_process() to start |
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* it. See also kthread_run(). The new thread has SCHED_NORMAL policy and |
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* is affine to all CPUs. |
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* |
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* If thread is going to be bound on a particular cpu, give its node |
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* in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. |
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* When woken, the thread will run @threadfn() with @data as its |
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* argument. @threadfn() can either call do_exit() directly if it is a |
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* standalone thread for which no one will call kthread_stop(), or |
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* return when 'kthread_should_stop()' is true (which means |
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* kthread_stop() has been called). The return value should be zero |
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* or a negative error number; it will be passed to kthread_stop(). |
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* |
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* Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). |
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*/ |
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struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), |
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void *data, int node, |
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const char namefmt[], |
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...) |
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{ |
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struct task_struct *task; |
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va_list args; |
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|
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va_start(args, namefmt); |
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task = __kthread_create_on_node(threadfn, data, node, namefmt, args); |
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va_end(args); |
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return task; |
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} |
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EXPORT_SYMBOL(kthread_create_on_node); |
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static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, unsigned int state) |
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{ |
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unsigned long flags; |
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|
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if (!wait_task_inactive(p, state)) { |
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WARN_ON(1); |
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return; |
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} |
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|
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/* It's safe because the task is inactive. */ |
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raw_spin_lock_irqsave(&p->pi_lock, flags); |
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do_set_cpus_allowed(p, mask); |
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p->flags |= PF_NO_SETAFFINITY; |
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raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
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} |
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static void __kthread_bind(struct task_struct *p, unsigned int cpu, unsigned int state) |
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{ |
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__kthread_bind_mask(p, cpumask_of(cpu), state); |
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} |
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|
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void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) |
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{ |
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__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); |
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} |
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|
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/** |
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* kthread_bind - bind a just-created kthread to a cpu. |
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* @p: thread created by kthread_create(). |
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* @cpu: cpu (might not be online, must be possible) for @k to run on. |
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* |
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* Description: This function is equivalent to set_cpus_allowed(), |
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* except that @cpu doesn't need to be online, and the thread must be |
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* stopped (i.e., just returned from kthread_create()). |
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*/ |
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void kthread_bind(struct task_struct *p, unsigned int cpu) |
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{ |
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__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
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} |
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EXPORT_SYMBOL(kthread_bind); |
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|
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/** |
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* kthread_create_on_cpu - Create a cpu bound kthread |
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* @threadfn: the function to run until signal_pending(current). |
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* @data: data ptr for @threadfn. |
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* @cpu: The cpu on which the thread should be bound, |
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* @namefmt: printf-style name for the thread. Format is restricted |
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* to "name.*%u". Code fills in cpu number. |
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* |
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* Description: This helper function creates and names a kernel thread |
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*/ |
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struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), |
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void *data, unsigned int cpu, |
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const char *namefmt) |
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{ |
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struct task_struct *p; |
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|
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p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
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cpu); |
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if (IS_ERR(p)) |
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return p; |
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kthread_bind(p, cpu); |
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/* CPU hotplug need to bind once again when unparking the thread. */ |
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to_kthread(p)->cpu = cpu; |
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return p; |
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} |
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|
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void kthread_set_per_cpu(struct task_struct *k, int cpu) |
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{ |
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struct kthread *kthread = to_kthread(k); |
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if (!kthread) |
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return; |
|
|
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WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY)); |
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|
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if (cpu < 0) { |
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clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
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return; |
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} |
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|
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kthread->cpu = cpu; |
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set_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
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} |
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|
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bool kthread_is_per_cpu(struct task_struct *p) |
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{ |
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struct kthread *kthread = __to_kthread(p); |
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if (!kthread) |
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return false; |
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|
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return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
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} |
|
|
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/** |
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* kthread_unpark - unpark a thread created by kthread_create(). |
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* @k: thread created by kthread_create(). |
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* |
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* Sets kthread_should_park() for @k to return false, wakes it, and |
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* waits for it to return. If the thread is marked percpu then its |
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* bound to the cpu again. |
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*/ |
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void kthread_unpark(struct task_struct *k) |
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{ |
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struct kthread *kthread = to_kthread(k); |
|
|
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/* |
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* Newly created kthread was parked when the CPU was offline. |
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* The binding was lost and we need to set it again. |
|
*/ |
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if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
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__kthread_bind(k, kthread->cpu, TASK_PARKED); |
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|
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clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
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/* |
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* __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. |
|
*/ |
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wake_up_state(k, TASK_PARKED); |
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} |
|
EXPORT_SYMBOL_GPL(kthread_unpark); |
|
|
|
/** |
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* kthread_park - park a thread created by kthread_create(). |
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* @k: thread created by kthread_create(). |
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* |
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* Sets kthread_should_park() for @k to return true, wakes it, and |
|
* waits for it to return. This can also be called after kthread_create() |
|
* instead of calling wake_up_process(): the thread will park without |
|
* calling threadfn(). |
|
* |
|
* Returns 0 if the thread is parked, -ENOSYS if the thread exited. |
|
* If called by the kthread itself just the park bit is set. |
|
*/ |
|
int kthread_park(struct task_struct *k) |
|
{ |
|
struct kthread *kthread = to_kthread(k); |
|
|
|
if (WARN_ON(k->flags & PF_EXITING)) |
|
return -ENOSYS; |
|
|
|
if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
|
return -EBUSY; |
|
|
|
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
|
if (k != current) { |
|
wake_up_process(k); |
|
/* |
|
* Wait for __kthread_parkme() to complete(), this means we |
|
* _will_ have TASK_PARKED and are about to call schedule(). |
|
*/ |
|
wait_for_completion(&kthread->parked); |
|
/* |
|
* Now wait for that schedule() to complete and the task to |
|
* get scheduled out. |
|
*/ |
|
WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); |
|
} |
|
|
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_park); |
|
|
|
/** |
|
* kthread_stop - stop a thread created by kthread_create(). |
|
* @k: thread created by kthread_create(). |
|
* |
|
* Sets kthread_should_stop() for @k to return true, wakes it, and |
|
* waits for it to exit. This can also be called after kthread_create() |
|
* instead of calling wake_up_process(): the thread will exit without |
|
* calling threadfn(). |
|
* |
|
* If threadfn() may call do_exit() itself, the caller must ensure |
|
* task_struct can't go away. |
|
* |
|
* Returns the result of threadfn(), or %-EINTR if wake_up_process() |
|
* was never called. |
|
*/ |
|
int kthread_stop(struct task_struct *k) |
|
{ |
|
struct kthread *kthread; |
|
int ret; |
|
|
|
trace_sched_kthread_stop(k); |
|
|
|
get_task_struct(k); |
|
kthread = to_kthread(k); |
|
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); |
|
kthread_unpark(k); |
|
wake_up_process(k); |
|
wait_for_completion(&kthread->exited); |
|
ret = k->exit_code; |
|
put_task_struct(k); |
|
|
|
trace_sched_kthread_stop_ret(ret); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(kthread_stop); |
|
|
|
int kthreadd(void *unused) |
|
{ |
|
struct task_struct *tsk = current; |
|
|
|
/* Setup a clean context for our children to inherit. */ |
|
set_task_comm(tsk, "kthreadd"); |
|
ignore_signals(tsk); |
|
set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_FLAG_KTHREAD)); |
|
set_mems_allowed(node_states[N_MEMORY]); |
|
|
|
current->flags |= PF_NOFREEZE; |
|
cgroup_init_kthreadd(); |
|
|
|
for (;;) { |
|
set_current_state(TASK_INTERRUPTIBLE); |
|
if (list_empty(&kthread_create_list)) |
|
schedule(); |
|
__set_current_state(TASK_RUNNING); |
|
|
|
spin_lock(&kthread_create_lock); |
|
while (!list_empty(&kthread_create_list)) { |
|
struct kthread_create_info *create; |
|
|
|
create = list_entry(kthread_create_list.next, |
|
struct kthread_create_info, list); |
|
list_del_init(&create->list); |
|
spin_unlock(&kthread_create_lock); |
|
|
|
create_kthread(create); |
|
|
|
spin_lock(&kthread_create_lock); |
|
} |
|
spin_unlock(&kthread_create_lock); |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
void __kthread_init_worker(struct kthread_worker *worker, |
|
const char *name, |
|
struct lock_class_key *key) |
|
{ |
|
memset(worker, 0, sizeof(struct kthread_worker)); |
|
raw_spin_lock_init(&worker->lock); |
|
lockdep_set_class_and_name(&worker->lock, key, name); |
|
INIT_LIST_HEAD(&worker->work_list); |
|
INIT_LIST_HEAD(&worker->delayed_work_list); |
|
} |
|
EXPORT_SYMBOL_GPL(__kthread_init_worker); |
|
|
|
/** |
|
* kthread_worker_fn - kthread function to process kthread_worker |
|
* @worker_ptr: pointer to initialized kthread_worker |
|
* |
|
* This function implements the main cycle of kthread worker. It processes |
|
* work_list until it is stopped with kthread_stop(). It sleeps when the queue |
|
* is empty. |
|
* |
|
* The works are not allowed to keep any locks, disable preemption or interrupts |
|
* when they finish. There is defined a safe point for freezing when one work |
|
* finishes and before a new one is started. |
|
* |
|
* Also the works must not be handled by more than one worker at the same time, |
|
* see also kthread_queue_work(). |
|
*/ |
|
int kthread_worker_fn(void *worker_ptr) |
|
{ |
|
struct kthread_worker *worker = worker_ptr; |
|
struct kthread_work *work; |
|
|
|
/* |
|
* FIXME: Update the check and remove the assignment when all kthread |
|
* worker users are created using kthread_create_worker*() functions. |
|
*/ |
|
WARN_ON(worker->task && worker->task != current); |
|
worker->task = current; |
|
|
|
if (worker->flags & KTW_FREEZABLE) |
|
set_freezable(); |
|
|
|
repeat: |
|
set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ |
|
|
|
if (kthread_should_stop()) { |
|
__set_current_state(TASK_RUNNING); |
|
raw_spin_lock_irq(&worker->lock); |
|
worker->task = NULL; |
|
raw_spin_unlock_irq(&worker->lock); |
|
return 0; |
|
} |
|
|
|
work = NULL; |
|
raw_spin_lock_irq(&worker->lock); |
|
if (!list_empty(&worker->work_list)) { |
|
work = list_first_entry(&worker->work_list, |
|
struct kthread_work, node); |
|
list_del_init(&work->node); |
|
} |
|
worker->current_work = work; |
|
raw_spin_unlock_irq(&worker->lock); |
|
|
|
if (work) { |
|
kthread_work_func_t func = work->func; |
|
__set_current_state(TASK_RUNNING); |
|
trace_sched_kthread_work_execute_start(work); |
|
work->func(work); |
|
/* |
|
* Avoid dereferencing work after this point. The trace |
|
* event only cares about the address. |
|
*/ |
|
trace_sched_kthread_work_execute_end(work, func); |
|
} else if (!freezing(current)) |
|
schedule(); |
|
|
|
try_to_freeze(); |
|
cond_resched(); |
|
goto repeat; |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_worker_fn); |
|
|
|
static __printf(3, 0) struct kthread_worker * |
|
__kthread_create_worker(int cpu, unsigned int flags, |
|
const char namefmt[], va_list args) |
|
{ |
|
struct kthread_worker *worker; |
|
struct task_struct *task; |
|
int node = NUMA_NO_NODE; |
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
|
if (!worker) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
kthread_init_worker(worker); |
|
|
|
if (cpu >= 0) |
|
node = cpu_to_node(cpu); |
|
|
|
task = __kthread_create_on_node(kthread_worker_fn, worker, |
|
node, namefmt, args); |
|
if (IS_ERR(task)) |
|
goto fail_task; |
|
|
|
if (cpu >= 0) |
|
kthread_bind(task, cpu); |
|
|
|
worker->flags = flags; |
|
worker->task = task; |
|
wake_up_process(task); |
|
return worker; |
|
|
|
fail_task: |
|
kfree(worker); |
|
return ERR_CAST(task); |
|
} |
|
|
|
/** |
|
* kthread_create_worker - create a kthread worker |
|
* @flags: flags modifying the default behavior of the worker |
|
* @namefmt: printf-style name for the kthread worker (task). |
|
* |
|
* Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) |
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR) |
|
* when the worker was SIGKILLed. |
|
*/ |
|
struct kthread_worker * |
|
kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
|
{ |
|
struct kthread_worker *worker; |
|
va_list args; |
|
|
|
va_start(args, namefmt); |
|
worker = __kthread_create_worker(-1, flags, namefmt, args); |
|
va_end(args); |
|
|
|
return worker; |
|
} |
|
EXPORT_SYMBOL(kthread_create_worker); |
|
|
|
/** |
|
* kthread_create_worker_on_cpu - create a kthread worker and bind it |
|
* to a given CPU and the associated NUMA node. |
|
* @cpu: CPU number |
|
* @flags: flags modifying the default behavior of the worker |
|
* @namefmt: printf-style name for the kthread worker (task). |
|
* |
|
* Use a valid CPU number if you want to bind the kthread worker |
|
* to the given CPU and the associated NUMA node. |
|
* |
|
* A good practice is to add the cpu number also into the worker name. |
|
* For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). |
|
* |
|
* CPU hotplug: |
|
* The kthread worker API is simple and generic. It just provides a way |
|
* to create, use, and destroy workers. |
|
* |
|
* It is up to the API user how to handle CPU hotplug. They have to decide |
|
* how to handle pending work items, prevent queuing new ones, and |
|
* restore the functionality when the CPU goes off and on. There are a |
|
* few catches: |
|
* |
|
* - CPU affinity gets lost when it is scheduled on an offline CPU. |
|
* |
|
* - The worker might not exist when the CPU was off when the user |
|
* created the workers. |
|
* |
|
* Good practice is to implement two CPU hotplug callbacks and to |
|
* destroy/create the worker when the CPU goes down/up. |
|
* |
|
* Return: |
|
* The pointer to the allocated worker on success, ERR_PTR(-ENOMEM) |
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR) |
|
* when the worker was SIGKILLed. |
|
*/ |
|
struct kthread_worker * |
|
kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
|
const char namefmt[], ...) |
|
{ |
|
struct kthread_worker *worker; |
|
va_list args; |
|
|
|
va_start(args, namefmt); |
|
worker = __kthread_create_worker(cpu, flags, namefmt, args); |
|
va_end(args); |
|
|
|
return worker; |
|
} |
|
EXPORT_SYMBOL(kthread_create_worker_on_cpu); |
|
|
|
/* |
|
* Returns true when the work could not be queued at the moment. |
|
* It happens when it is already pending in a worker list |
|
* or when it is being cancelled. |
|
*/ |
|
static inline bool queuing_blocked(struct kthread_worker *worker, |
|
struct kthread_work *work) |
|
{ |
|
lockdep_assert_held(&worker->lock); |
|
|
|
return !list_empty(&work->node) || work->canceling; |
|
} |
|
|
|
static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
|
struct kthread_work *work) |
|
{ |
|
lockdep_assert_held(&worker->lock); |
|
WARN_ON_ONCE(!list_empty(&work->node)); |
|
/* Do not use a work with >1 worker, see kthread_queue_work() */ |
|
WARN_ON_ONCE(work->worker && work->worker != worker); |
|
} |
|
|
|
/* insert @work before @pos in @worker */ |
|
static void kthread_insert_work(struct kthread_worker *worker, |
|
struct kthread_work *work, |
|
struct list_head *pos) |
|
{ |
|
kthread_insert_work_sanity_check(worker, work); |
|
|
|
trace_sched_kthread_work_queue_work(worker, work); |
|
|
|
list_add_tail(&work->node, pos); |
|
work->worker = worker; |
|
if (!worker->current_work && likely(worker->task)) |
|
wake_up_process(worker->task); |
|
} |
|
|
|
/** |
|
* kthread_queue_work - queue a kthread_work |
|
* @worker: target kthread_worker |
|
* @work: kthread_work to queue |
|
* |
|
* Queue @work to work processor @task for async execution. @task |
|
* must have been created with kthread_worker_create(). Returns %true |
|
* if @work was successfully queued, %false if it was already pending. |
|
* |
|
* Reinitialize the work if it needs to be used by another worker. |
|
* For example, when the worker was stopped and started again. |
|
*/ |
|
bool kthread_queue_work(struct kthread_worker *worker, |
|
struct kthread_work *work) |
|
{ |
|
bool ret = false; |
|
unsigned long flags; |
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
if (!queuing_blocked(worker, work)) { |
|
kthread_insert_work(worker, work, &worker->work_list); |
|
ret = true; |
|
} |
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_queue_work); |
|
|
|
/** |
|
* kthread_delayed_work_timer_fn - callback that queues the associated kthread |
|
* delayed work when the timer expires. |
|
* @t: pointer to the expired timer |
|
* |
|
* The format of the function is defined by struct timer_list. |
|
* It should have been called from irqsafe timer with irq already off. |
|
*/ |
|
void kthread_delayed_work_timer_fn(struct timer_list *t) |
|
{ |
|
struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
|
struct kthread_work *work = &dwork->work; |
|
struct kthread_worker *worker = work->worker; |
|
unsigned long flags; |
|
|
|
/* |
|
* This might happen when a pending work is reinitialized. |
|
* It means that it is used a wrong way. |
|
*/ |
|
if (WARN_ON_ONCE(!worker)) |
|
return; |
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */ |
|
WARN_ON_ONCE(work->worker != worker); |
|
|
|
/* Move the work from worker->delayed_work_list. */ |
|
WARN_ON_ONCE(list_empty(&work->node)); |
|
list_del_init(&work->node); |
|
if (!work->canceling) |
|
kthread_insert_work(worker, work, &worker->work_list); |
|
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
} |
|
EXPORT_SYMBOL(kthread_delayed_work_timer_fn); |
|
|
|
static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
|
struct kthread_delayed_work *dwork, |
|
unsigned long delay) |
|
{ |
|
struct timer_list *timer = &dwork->timer; |
|
struct kthread_work *work = &dwork->work; |
|
|
|
WARN_ON_FUNCTION_MISMATCH(timer->function, |
|
kthread_delayed_work_timer_fn); |
|
|
|
/* |
|
* 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) { |
|
kthread_insert_work(worker, work, &worker->work_list); |
|
return; |
|
} |
|
|
|
/* Be paranoid and try to detect possible races already now. */ |
|
kthread_insert_work_sanity_check(worker, work); |
|
|
|
list_add(&work->node, &worker->delayed_work_list); |
|
work->worker = worker; |
|
timer->expires = jiffies + delay; |
|
add_timer(timer); |
|
} |
|
|
|
/** |
|
* kthread_queue_delayed_work - queue the associated kthread work |
|
* after a delay. |
|
* @worker: target kthread_worker |
|
* @dwork: kthread_delayed_work to queue |
|
* @delay: number of jiffies to wait before queuing |
|
* |
|
* If the work has not been pending it starts a timer that will queue |
|
* the work after the given @delay. If @delay is zero, it queues the |
|
* work immediately. |
|
* |
|
* Return: %false if the @work has already been pending. It means that |
|
* either the timer was running or the work was queued. It returns %true |
|
* otherwise. |
|
*/ |
|
bool kthread_queue_delayed_work(struct kthread_worker *worker, |
|
struct kthread_delayed_work *dwork, |
|
unsigned long delay) |
|
{ |
|
struct kthread_work *work = &dwork->work; |
|
unsigned long flags; |
|
bool ret = false; |
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
|
|
if (!queuing_blocked(worker, work)) { |
|
__kthread_queue_delayed_work(worker, dwork, delay); |
|
ret = true; |
|
} |
|
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); |
|
|
|
struct kthread_flush_work { |
|
struct kthread_work work; |
|
struct completion done; |
|
}; |
|
|
|
static void kthread_flush_work_fn(struct kthread_work *work) |
|
{ |
|
struct kthread_flush_work *fwork = |
|
container_of(work, struct kthread_flush_work, work); |
|
complete(&fwork->done); |
|
} |
|
|
|
/** |
|
* kthread_flush_work - flush a kthread_work |
|
* @work: work to flush |
|
* |
|
* If @work is queued or executing, wait for it to finish execution. |
|
*/ |
|
void kthread_flush_work(struct kthread_work *work) |
|
{ |
|
struct kthread_flush_work fwork = { |
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), |
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done), |
|
}; |
|
struct kthread_worker *worker; |
|
bool noop = false; |
|
|
|
worker = work->worker; |
|
if (!worker) |
|
return; |
|
|
|
raw_spin_lock_irq(&worker->lock); |
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */ |
|
WARN_ON_ONCE(work->worker != worker); |
|
|
|
if (!list_empty(&work->node)) |
|
kthread_insert_work(worker, &fwork.work, work->node.next); |
|
else if (worker->current_work == work) |
|
kthread_insert_work(worker, &fwork.work, |
|
worker->work_list.next); |
|
else |
|
noop = true; |
|
|
|
raw_spin_unlock_irq(&worker->lock); |
|
|
|
if (!noop) |
|
wait_for_completion(&fwork.done); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_flush_work); |
|
|
|
/* |
|
* Make sure that the timer is neither set nor running and could |
|
* not manipulate the work list_head any longer. |
|
* |
|
* The function is called under worker->lock. The lock is temporary |
|
* released but the timer can't be set again in the meantime. |
|
*/ |
|
static void kthread_cancel_delayed_work_timer(struct kthread_work *work, |
|
unsigned long *flags) |
|
{ |
|
struct kthread_delayed_work *dwork = |
|
container_of(work, struct kthread_delayed_work, work); |
|
struct kthread_worker *worker = work->worker; |
|
|
|
/* |
|
* del_timer_sync() must be called to make sure that the timer |
|
* callback is not running. The lock must be temporary released |
|
* to avoid a deadlock with the callback. In the meantime, |
|
* any queuing is blocked by setting the canceling counter. |
|
*/ |
|
work->canceling++; |
|
raw_spin_unlock_irqrestore(&worker->lock, *flags); |
|
del_timer_sync(&dwork->timer); |
|
raw_spin_lock_irqsave(&worker->lock, *flags); |
|
work->canceling--; |
|
} |
|
|
|
/* |
|
* This function removes the work from the worker queue. |
|
* |
|
* It is called under worker->lock. The caller must make sure that |
|
* the timer used by delayed work is not running, e.g. by calling |
|
* kthread_cancel_delayed_work_timer(). |
|
* |
|
* The work might still be in use when this function finishes. See the |
|
* current_work proceed by the worker. |
|
* |
|
* Return: %true if @work was pending and successfully canceled, |
|
* %false if @work was not pending |
|
*/ |
|
static bool __kthread_cancel_work(struct kthread_work *work) |
|
{ |
|
/* |
|
* Try to remove the work from a worker list. It might either |
|
* be from worker->work_list or from worker->delayed_work_list. |
|
*/ |
|
if (!list_empty(&work->node)) { |
|
list_del_init(&work->node); |
|
return true; |
|
} |
|
|
|
return false; |
|
} |
|
|
|
/** |
|
* kthread_mod_delayed_work - modify delay of or queue a kthread delayed work |
|
* @worker: kthread worker to use |
|
* @dwork: kthread delayed work to queue |
|
* @delay: number of jiffies to wait before queuing |
|
* |
|
* If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, |
|
* modify @dwork's timer so that it expires after @delay. If @delay is zero, |
|
* @work is guaranteed to be queued immediately. |
|
* |
|
* Return: %false if @dwork was idle and queued, %true otherwise. |
|
* |
|
* A special case is when the work is being canceled in parallel. |
|
* It might be caused either by the real kthread_cancel_delayed_work_sync() |
|
* or yet another kthread_mod_delayed_work() call. We let the other command |
|
* win and return %true here. The return value can be used for reference |
|
* counting and the number of queued works stays the same. Anyway, the caller |
|
* is supposed to synchronize these operations a reasonable way. |
|
* |
|
* This function is safe to call from any context including IRQ handler. |
|
* See __kthread_cancel_work() and kthread_delayed_work_timer_fn() |
|
* for details. |
|
*/ |
|
bool kthread_mod_delayed_work(struct kthread_worker *worker, |
|
struct kthread_delayed_work *dwork, |
|
unsigned long delay) |
|
{ |
|
struct kthread_work *work = &dwork->work; |
|
unsigned long flags; |
|
int ret; |
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
|
|
/* Do not bother with canceling when never queued. */ |
|
if (!work->worker) { |
|
ret = false; |
|
goto fast_queue; |
|
} |
|
|
|
/* Work must not be used with >1 worker, see kthread_queue_work() */ |
|
WARN_ON_ONCE(work->worker != worker); |
|
|
|
/* |
|
* Temporary cancel the work but do not fight with another command |
|
* that is canceling the work as well. |
|
* |
|
* It is a bit tricky because of possible races with another |
|
* mod_delayed_work() and cancel_delayed_work() callers. |
|
* |
|
* The timer must be canceled first because worker->lock is released |
|
* when doing so. But the work can be removed from the queue (list) |
|
* only when it can be queued again so that the return value can |
|
* be used for reference counting. |
|
*/ |
|
kthread_cancel_delayed_work_timer(work, &flags); |
|
if (work->canceling) { |
|
/* The number of works in the queue does not change. */ |
|
ret = true; |
|
goto out; |
|
} |
|
ret = __kthread_cancel_work(work); |
|
|
|
fast_queue: |
|
__kthread_queue_delayed_work(worker, dwork, delay); |
|
out: |
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); |
|
|
|
static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
|
{ |
|
struct kthread_worker *worker = work->worker; |
|
unsigned long flags; |
|
int ret = false; |
|
|
|
if (!worker) |
|
goto out; |
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */ |
|
WARN_ON_ONCE(work->worker != worker); |
|
|
|
if (is_dwork) |
|
kthread_cancel_delayed_work_timer(work, &flags); |
|
|
|
ret = __kthread_cancel_work(work); |
|
|
|
if (worker->current_work != work) |
|
goto out_fast; |
|
|
|
/* |
|
* The work is in progress and we need to wait with the lock released. |
|
* In the meantime, block any queuing by setting the canceling counter. |
|
*/ |
|
work->canceling++; |
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
kthread_flush_work(work); |
|
raw_spin_lock_irqsave(&worker->lock, flags); |
|
work->canceling--; |
|
|
|
out_fast: |
|
raw_spin_unlock_irqrestore(&worker->lock, flags); |
|
out: |
|
return ret; |
|
} |
|
|
|
/** |
|
* kthread_cancel_work_sync - cancel a kthread work and wait for it to finish |
|
* @work: the kthread work to cancel |
|
* |
|
* Cancel @work and wait for its execution to finish. This function |
|
* can be used even if the work re-queues itself. On return from this |
|
* function, @work is guaranteed to be not pending or executing on any CPU. |
|
* |
|
* kthread_cancel_work_sync(&delayed_work->work) must not be used for |
|
* delayed_work's. Use kthread_cancel_delayed_work_sync() instead. |
|
* |
|
* The caller must ensure that the worker on which @work was last |
|
* queued can't be destroyed before this function returns. |
|
* |
|
* Return: %true if @work was pending, %false otherwise. |
|
*/ |
|
bool kthread_cancel_work_sync(struct kthread_work *work) |
|
{ |
|
return __kthread_cancel_work_sync(work, false); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); |
|
|
|
/** |
|
* kthread_cancel_delayed_work_sync - cancel a kthread delayed work and |
|
* wait for it to finish. |
|
* @dwork: the kthread delayed work to cancel |
|
* |
|
* This is kthread_cancel_work_sync() for delayed works. |
|
* |
|
* Return: %true if @dwork was pending, %false otherwise. |
|
*/ |
|
bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) |
|
{ |
|
return __kthread_cancel_work_sync(&dwork->work, true); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); |
|
|
|
/** |
|
* kthread_flush_worker - flush all current works on a kthread_worker |
|
* @worker: worker to flush |
|
* |
|
* Wait until all currently executing or pending works on @worker are |
|
* finished. |
|
*/ |
|
void kthread_flush_worker(struct kthread_worker *worker) |
|
{ |
|
struct kthread_flush_work fwork = { |
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), |
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done), |
|
}; |
|
|
|
kthread_queue_work(worker, &fwork.work); |
|
wait_for_completion(&fwork.done); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_flush_worker); |
|
|
|
/** |
|
* kthread_destroy_worker - destroy a kthread worker |
|
* @worker: worker to be destroyed |
|
* |
|
* Flush and destroy @worker. The simple flush is enough because the kthread |
|
* worker API is used only in trivial scenarios. There are no multi-step state |
|
* machines needed. |
|
*/ |
|
void kthread_destroy_worker(struct kthread_worker *worker) |
|
{ |
|
struct task_struct *task; |
|
|
|
task = worker->task; |
|
if (WARN_ON(!task)) |
|
return; |
|
|
|
kthread_flush_worker(worker); |
|
kthread_stop(task); |
|
WARN_ON(!list_empty(&worker->work_list)); |
|
kfree(worker); |
|
} |
|
EXPORT_SYMBOL(kthread_destroy_worker); |
|
|
|
/** |
|
* kthread_use_mm - make the calling kthread operate on an address space |
|
* @mm: address space to operate on |
|
*/ |
|
void kthread_use_mm(struct mm_struct *mm) |
|
{ |
|
struct mm_struct *active_mm; |
|
struct task_struct *tsk = current; |
|
|
|
WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
|
WARN_ON_ONCE(tsk->mm); |
|
|
|
task_lock(tsk); |
|
/* Hold off tlb flush IPIs while switching mm's */ |
|
local_irq_disable(); |
|
active_mm = tsk->active_mm; |
|
if (active_mm != mm) { |
|
mmgrab(mm); |
|
tsk->active_mm = mm; |
|
} |
|
tsk->mm = mm; |
|
membarrier_update_current_mm(mm); |
|
switch_mm_irqs_off(active_mm, mm, tsk); |
|
local_irq_enable(); |
|
task_unlock(tsk); |
|
#ifdef finish_arch_post_lock_switch |
|
finish_arch_post_lock_switch(); |
|
#endif |
|
|
|
/* |
|
* When a kthread starts operating on an address space, the loop |
|
* in membarrier_{private,global}_expedited() may not observe |
|
* that tsk->mm, and not issue an IPI. Membarrier requires a |
|
* memory barrier after storing to tsk->mm, before accessing |
|
* user-space memory. A full memory barrier for membarrier |
|
* {PRIVATE,GLOBAL}_EXPEDITED is implicitly provided by |
|
* mmdrop(), or explicitly with smp_mb(). |
|
*/ |
|
if (active_mm != mm) |
|
mmdrop(active_mm); |
|
else |
|
smp_mb(); |
|
|
|
to_kthread(tsk)->oldfs = force_uaccess_begin(); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_use_mm); |
|
|
|
/** |
|
* kthread_unuse_mm - reverse the effect of kthread_use_mm() |
|
* @mm: address space to operate on |
|
*/ |
|
void kthread_unuse_mm(struct mm_struct *mm) |
|
{ |
|
struct task_struct *tsk = current; |
|
|
|
WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
|
WARN_ON_ONCE(!tsk->mm); |
|
|
|
force_uaccess_end(to_kthread(tsk)->oldfs); |
|
|
|
task_lock(tsk); |
|
/* |
|
* When a kthread stops operating on an address space, the loop |
|
* in membarrier_{private,global}_expedited() may not observe |
|
* that tsk->mm, and not issue an IPI. Membarrier requires a |
|
* memory barrier after accessing user-space memory, before |
|
* clearing tsk->mm. |
|
*/ |
|
smp_mb__after_spinlock(); |
|
sync_mm_rss(mm); |
|
local_irq_disable(); |
|
tsk->mm = NULL; |
|
membarrier_update_current_mm(NULL); |
|
/* active_mm is still 'mm' */ |
|
enter_lazy_tlb(mm, tsk); |
|
local_irq_enable(); |
|
task_unlock(tsk); |
|
} |
|
EXPORT_SYMBOL_GPL(kthread_unuse_mm); |
|
|
|
#ifdef CONFIG_BLK_CGROUP |
|
/** |
|
* kthread_associate_blkcg - associate blkcg to current kthread |
|
* @css: the cgroup info |
|
* |
|
* Current thread must be a kthread. The thread is running jobs on behalf of |
|
* other threads. In some cases, we expect the jobs attach cgroup info of |
|
* original threads instead of that of current thread. This function stores |
|
* original thread's cgroup info in current kthread context for later |
|
* retrieval. |
|
*/ |
|
void kthread_associate_blkcg(struct cgroup_subsys_state *css) |
|
{ |
|
struct kthread *kthread; |
|
|
|
if (!(current->flags & PF_KTHREAD)) |
|
return; |
|
kthread = to_kthread(current); |
|
if (!kthread) |
|
return; |
|
|
|
if (kthread->blkcg_css) { |
|
css_put(kthread->blkcg_css); |
|
kthread->blkcg_css = NULL; |
|
} |
|
if (css) { |
|
css_get(css); |
|
kthread->blkcg_css = css; |
|
} |
|
} |
|
EXPORT_SYMBOL(kthread_associate_blkcg); |
|
|
|
/** |
|
* kthread_blkcg - get associated blkcg css of current kthread |
|
* |
|
* Current thread must be a kthread. |
|
*/ |
|
struct cgroup_subsys_state *kthread_blkcg(void) |
|
{ |
|
struct kthread *kthread; |
|
|
|
if (current->flags & PF_KTHREAD) { |
|
kthread = to_kthread(current); |
|
if (kthread) |
|
return kthread->blkcg_css; |
|
} |
|
return NULL; |
|
} |
|
EXPORT_SYMBOL(kthread_blkcg); |
|
#endif
|
|
|