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675 lines
22 KiB
675 lines
22 KiB
/* |
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* Sleepable Read-Copy Update mechanism for mutual exclusion. |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, you can access it online at |
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* http://www.gnu.org/licenses/gpl-2.0.html. |
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* |
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* Copyright (C) IBM Corporation, 2006 |
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* Copyright (C) Fujitsu, 2012 |
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* |
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* Author: Paul McKenney <[email protected]> |
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* Lai Jiangshan <[email protected]> |
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* |
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* For detailed explanation of Read-Copy Update mechanism see - |
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* Documentation/RCU/ *.txt |
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* |
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*/ |
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#include <linux/export.h> |
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#include <linux/mutex.h> |
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#include <linux/percpu.h> |
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#include <linux/preempt.h> |
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#include <linux/rcupdate.h> |
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#include <linux/sched.h> |
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#include <linux/smp.h> |
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#include <linux/delay.h> |
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#include <linux/srcu.h> |
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#include "rcu.h" |
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/* |
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* Initialize an rcu_batch structure to empty. |
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*/ |
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static inline void rcu_batch_init(struct rcu_batch *b) |
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{ |
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b->head = NULL; |
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b->tail = &b->head; |
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} |
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/* |
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* Enqueue a callback onto the tail of the specified rcu_batch structure. |
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*/ |
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static inline void rcu_batch_queue(struct rcu_batch *b, struct rcu_head *head) |
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{ |
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*b->tail = head; |
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b->tail = &head->next; |
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} |
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/* |
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* Is the specified rcu_batch structure empty? |
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*/ |
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static inline bool rcu_batch_empty(struct rcu_batch *b) |
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{ |
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return b->tail == &b->head; |
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} |
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/* |
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* Remove the callback at the head of the specified rcu_batch structure |
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* and return a pointer to it, or return NULL if the structure is empty. |
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*/ |
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static inline struct rcu_head *rcu_batch_dequeue(struct rcu_batch *b) |
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{ |
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struct rcu_head *head; |
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|
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if (rcu_batch_empty(b)) |
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return NULL; |
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head = b->head; |
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b->head = head->next; |
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if (b->tail == &head->next) |
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rcu_batch_init(b); |
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return head; |
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} |
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/* |
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* Move all callbacks from the rcu_batch structure specified by "from" to |
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* the structure specified by "to". |
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*/ |
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static inline void rcu_batch_move(struct rcu_batch *to, struct rcu_batch *from) |
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{ |
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if (!rcu_batch_empty(from)) { |
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*to->tail = from->head; |
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to->tail = from->tail; |
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rcu_batch_init(from); |
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} |
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} |
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static int init_srcu_struct_fields(struct srcu_struct *sp) |
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{ |
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sp->completed = 0; |
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spin_lock_init(&sp->queue_lock); |
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sp->running = false; |
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rcu_batch_init(&sp->batch_queue); |
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rcu_batch_init(&sp->batch_check0); |
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rcu_batch_init(&sp->batch_check1); |
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rcu_batch_init(&sp->batch_done); |
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INIT_DELAYED_WORK(&sp->work, process_srcu); |
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sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array); |
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return sp->per_cpu_ref ? 0 : -ENOMEM; |
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} |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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int __init_srcu_struct(struct srcu_struct *sp, const char *name, |
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struct lock_class_key *key) |
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{ |
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/* Don't re-initialize a lock while it is held. */ |
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debug_check_no_locks_freed((void *)sp, sizeof(*sp)); |
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lockdep_init_map(&sp->dep_map, name, key, 0); |
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return init_srcu_struct_fields(sp); |
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} |
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EXPORT_SYMBOL_GPL(__init_srcu_struct); |
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
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/** |
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* init_srcu_struct - initialize a sleep-RCU structure |
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* @sp: structure to initialize. |
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* |
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* Must invoke this on a given srcu_struct before passing that srcu_struct |
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* to any other function. Each srcu_struct represents a separate domain |
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* of SRCU protection. |
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*/ |
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int init_srcu_struct(struct srcu_struct *sp) |
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{ |
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return init_srcu_struct_fields(sp); |
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} |
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EXPORT_SYMBOL_GPL(init_srcu_struct); |
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
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/* |
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* Returns approximate total of the readers' ->seq[] values for the |
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* rank of per-CPU counters specified by idx. |
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*/ |
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static unsigned long srcu_readers_seq_idx(struct srcu_struct *sp, int idx) |
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{ |
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int cpu; |
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unsigned long sum = 0; |
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unsigned long t; |
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for_each_possible_cpu(cpu) { |
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t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]); |
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sum += t; |
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} |
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return sum; |
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} |
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/* |
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* Returns approximate number of readers active on the specified rank |
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* of the per-CPU ->c[] counters. |
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*/ |
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static unsigned long srcu_readers_active_idx(struct srcu_struct *sp, int idx) |
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{ |
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int cpu; |
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unsigned long sum = 0; |
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unsigned long t; |
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for_each_possible_cpu(cpu) { |
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t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]); |
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sum += t; |
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} |
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return sum; |
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} |
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/* |
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* Return true if the number of pre-existing readers is determined to |
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* be stably zero. An example unstable zero can occur if the call |
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* to srcu_readers_active_idx() misses an __srcu_read_lock() increment, |
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* but due to task migration, sees the corresponding __srcu_read_unlock() |
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* decrement. This can happen because srcu_readers_active_idx() takes |
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* time to sum the array, and might in fact be interrupted or preempted |
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* partway through the summation. |
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*/ |
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static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx) |
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{ |
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unsigned long seq; |
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seq = srcu_readers_seq_idx(sp, idx); |
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/* |
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* The following smp_mb() A pairs with the smp_mb() B located in |
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* __srcu_read_lock(). This pairing ensures that if an |
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* __srcu_read_lock() increments its counter after the summation |
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* in srcu_readers_active_idx(), then the corresponding SRCU read-side |
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* critical section will see any changes made prior to the start |
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* of the current SRCU grace period. |
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* |
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* Also, if the above call to srcu_readers_seq_idx() saw the |
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* increment of ->seq[], then the call to srcu_readers_active_idx() |
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* must see the increment of ->c[]. |
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*/ |
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smp_mb(); /* A */ |
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/* |
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* Note that srcu_readers_active_idx() can incorrectly return |
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* zero even though there is a pre-existing reader throughout. |
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* To see this, suppose that task A is in a very long SRCU |
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* read-side critical section that started on CPU 0, and that |
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* no other reader exists, so that the sum of the counters |
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* is equal to one. Then suppose that task B starts executing |
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* srcu_readers_active_idx(), summing up to CPU 1, and then that |
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* task C starts reading on CPU 0, so that its increment is not |
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* summed, but finishes reading on CPU 2, so that its decrement |
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* -is- summed. Then when task B completes its sum, it will |
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* incorrectly get zero, despite the fact that task A has been |
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* in its SRCU read-side critical section the whole time. |
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* |
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* We therefore do a validation step should srcu_readers_active_idx() |
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* return zero. |
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*/ |
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if (srcu_readers_active_idx(sp, idx) != 0) |
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return false; |
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/* |
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* The remainder of this function is the validation step. |
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* The following smp_mb() D pairs with the smp_mb() C in |
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* __srcu_read_unlock(). If the __srcu_read_unlock() was seen |
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* by srcu_readers_active_idx() above, then any destructive |
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* operation performed after the grace period will happen after |
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* the corresponding SRCU read-side critical section. |
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* |
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* Note that there can be at most NR_CPUS worth of readers using |
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* the old index, which is not enough to overflow even a 32-bit |
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* integer. (Yes, this does mean that systems having more than |
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* a billion or so CPUs need to be 64-bit systems.) Therefore, |
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* the sum of the ->seq[] counters cannot possibly overflow. |
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* Therefore, the only way that the return values of the two |
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* calls to srcu_readers_seq_idx() can be equal is if there were |
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* no increments of the corresponding rank of ->seq[] counts |
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* in the interim. But the missed-increment scenario laid out |
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* above includes an increment of the ->seq[] counter by |
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* the corresponding __srcu_read_lock(). Therefore, if this |
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* scenario occurs, the return values from the two calls to |
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* srcu_readers_seq_idx() will differ, and thus the validation |
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* step below suffices. |
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*/ |
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smp_mb(); /* D */ |
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return srcu_readers_seq_idx(sp, idx) == seq; |
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} |
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/** |
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* srcu_readers_active - returns true if there are readers. and false |
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* otherwise |
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* @sp: which srcu_struct to count active readers (holding srcu_read_lock). |
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* |
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* Note that this is not an atomic primitive, and can therefore suffer |
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* severe errors when invoked on an active srcu_struct. That said, it |
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* can be useful as an error check at cleanup time. |
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*/ |
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static bool srcu_readers_active(struct srcu_struct *sp) |
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{ |
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int cpu; |
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unsigned long sum = 0; |
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for_each_possible_cpu(cpu) { |
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sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]); |
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sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]); |
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} |
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return sum; |
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} |
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/** |
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* cleanup_srcu_struct - deconstruct a sleep-RCU structure |
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* @sp: structure to clean up. |
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* |
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* Must invoke this after you are finished using a given srcu_struct that |
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* was initialized via init_srcu_struct(), else you leak memory. |
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*/ |
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void cleanup_srcu_struct(struct srcu_struct *sp) |
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{ |
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if (WARN_ON(srcu_readers_active(sp))) |
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return; /* Leakage unless caller handles error. */ |
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free_percpu(sp->per_cpu_ref); |
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sp->per_cpu_ref = NULL; |
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} |
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EXPORT_SYMBOL_GPL(cleanup_srcu_struct); |
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/* |
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* Counts the new reader in the appropriate per-CPU element of the |
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* srcu_struct. Must be called from process context. |
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* Returns an index that must be passed to the matching srcu_read_unlock(). |
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*/ |
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int __srcu_read_lock(struct srcu_struct *sp) |
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{ |
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int idx; |
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idx = READ_ONCE(sp->completed) & 0x1; |
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__this_cpu_inc(sp->per_cpu_ref->c[idx]); |
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smp_mb(); /* B */ /* Avoid leaking the critical section. */ |
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__this_cpu_inc(sp->per_cpu_ref->seq[idx]); |
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return idx; |
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} |
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EXPORT_SYMBOL_GPL(__srcu_read_lock); |
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/* |
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* Removes the count for the old reader from the appropriate per-CPU |
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* element of the srcu_struct. Note that this may well be a different |
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* CPU than that which was incremented by the corresponding srcu_read_lock(). |
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* Must be called from process context. |
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*/ |
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void __srcu_read_unlock(struct srcu_struct *sp, int idx) |
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{ |
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smp_mb(); /* C */ /* Avoid leaking the critical section. */ |
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this_cpu_dec(sp->per_cpu_ref->c[idx]); |
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} |
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EXPORT_SYMBOL_GPL(__srcu_read_unlock); |
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/* |
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* We use an adaptive strategy for synchronize_srcu() and especially for |
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* synchronize_srcu_expedited(). We spin for a fixed time period |
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* (defined below) to allow SRCU readers to exit their read-side critical |
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* sections. If there are still some readers after 10 microseconds, |
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* we repeatedly block for 1-millisecond time periods. This approach |
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* has done well in testing, so there is no need for a config parameter. |
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*/ |
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#define SRCU_RETRY_CHECK_DELAY 5 |
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#define SYNCHRONIZE_SRCU_TRYCOUNT 2 |
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#define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 12 |
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/* |
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* @@@ Wait until all pre-existing readers complete. Such readers |
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* will have used the index specified by "idx". |
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* the caller should ensures the ->completed is not changed while checking |
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* and idx = (->completed & 1) ^ 1 |
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*/ |
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static bool try_check_zero(struct srcu_struct *sp, int idx, int trycount) |
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{ |
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for (;;) { |
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if (srcu_readers_active_idx_check(sp, idx)) |
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return true; |
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if (--trycount <= 0) |
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return false; |
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udelay(SRCU_RETRY_CHECK_DELAY); |
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} |
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} |
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/* |
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* Increment the ->completed counter so that future SRCU readers will |
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* use the other rank of the ->c[] and ->seq[] arrays. This allows |
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* us to wait for pre-existing readers in a starvation-free manner. |
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*/ |
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static void srcu_flip(struct srcu_struct *sp) |
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{ |
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sp->completed++; |
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} |
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/* |
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* Enqueue an SRCU callback on the specified srcu_struct structure, |
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* initiating grace-period processing if it is not already running. |
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* |
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* Note that all CPUs must agree that the grace period extended beyond |
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* all pre-existing SRCU read-side critical section. On systems with |
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* more than one CPU, this means that when "func()" is invoked, each CPU |
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* is guaranteed to have executed a full memory barrier since the end of |
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* its last corresponding SRCU read-side critical section whose beginning |
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* preceded the call to call_rcu(). It also means that each CPU executing |
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* an SRCU read-side critical section that continues beyond the start of |
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* "func()" must have executed a memory barrier after the call_rcu() |
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* but before the beginning of that SRCU read-side critical section. |
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* Note that these guarantees include CPUs that are offline, idle, or |
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* executing in user mode, as well as CPUs that are executing in the kernel. |
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* |
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* Furthermore, if CPU A invoked call_rcu() and CPU B invoked the |
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* resulting SRCU callback function "func()", then both CPU A and CPU |
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* B are guaranteed to execute a full memory barrier during the time |
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* interval between the call to call_rcu() and the invocation of "func()". |
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* This guarantee applies even if CPU A and CPU B are the same CPU (but |
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* again only if the system has more than one CPU). |
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* |
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* Of course, these guarantees apply only for invocations of call_srcu(), |
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* srcu_read_lock(), and srcu_read_unlock() that are all passed the same |
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* srcu_struct structure. |
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*/ |
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void call_srcu(struct srcu_struct *sp, struct rcu_head *head, |
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rcu_callback_t func) |
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{ |
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unsigned long flags; |
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head->next = NULL; |
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head->func = func; |
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spin_lock_irqsave(&sp->queue_lock, flags); |
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rcu_batch_queue(&sp->batch_queue, head); |
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if (!sp->running) { |
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sp->running = true; |
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queue_delayed_work(system_power_efficient_wq, &sp->work, 0); |
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} |
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spin_unlock_irqrestore(&sp->queue_lock, flags); |
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} |
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EXPORT_SYMBOL_GPL(call_srcu); |
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static void srcu_advance_batches(struct srcu_struct *sp, int trycount); |
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static void srcu_reschedule(struct srcu_struct *sp); |
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/* |
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* Helper function for synchronize_srcu() and synchronize_srcu_expedited(). |
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*/ |
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static void __synchronize_srcu(struct srcu_struct *sp, int trycount) |
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{ |
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struct rcu_synchronize rcu; |
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struct rcu_head *head = &rcu.head; |
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bool done = false; |
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RCU_LOCKDEP_WARN(lock_is_held(&sp->dep_map) || |
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lock_is_held(&rcu_bh_lock_map) || |
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lock_is_held(&rcu_lock_map) || |
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lock_is_held(&rcu_sched_lock_map), |
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"Illegal synchronize_srcu() in same-type SRCU (or in RCU) read-side critical section"); |
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might_sleep(); |
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init_completion(&rcu.completion); |
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head->next = NULL; |
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head->func = wakeme_after_rcu; |
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spin_lock_irq(&sp->queue_lock); |
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if (!sp->running) { |
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/* steal the processing owner */ |
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sp->running = true; |
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rcu_batch_queue(&sp->batch_check0, head); |
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spin_unlock_irq(&sp->queue_lock); |
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srcu_advance_batches(sp, trycount); |
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if (!rcu_batch_empty(&sp->batch_done)) { |
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BUG_ON(sp->batch_done.head != head); |
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rcu_batch_dequeue(&sp->batch_done); |
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done = true; |
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} |
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/* give the processing owner to work_struct */ |
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srcu_reschedule(sp); |
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} else { |
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rcu_batch_queue(&sp->batch_queue, head); |
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spin_unlock_irq(&sp->queue_lock); |
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} |
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if (!done) |
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wait_for_completion(&rcu.completion); |
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} |
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/** |
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* synchronize_srcu - wait for prior SRCU read-side critical-section completion |
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* @sp: srcu_struct with which to synchronize. |
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* |
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* Wait for the count to drain to zero of both indexes. To avoid the |
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* possible starvation of synchronize_srcu(), it waits for the count of |
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* the index=((->completed & 1) ^ 1) to drain to zero at first, |
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* and then flip the completed and wait for the count of the other index. |
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* |
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* Can block; must be called from process context. |
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* |
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* Note that it is illegal to call synchronize_srcu() from the corresponding |
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* SRCU read-side critical section; doing so will result in deadlock. |
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* However, it is perfectly legal to call synchronize_srcu() on one |
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* srcu_struct from some other srcu_struct's read-side critical section, |
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* as long as the resulting graph of srcu_structs is acyclic. |
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* |
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* There are memory-ordering constraints implied by synchronize_srcu(). |
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* On systems with more than one CPU, when synchronize_srcu() returns, |
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* each CPU is guaranteed to have executed a full memory barrier since |
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* the end of its last corresponding SRCU-sched read-side critical section |
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* whose beginning preceded the call to synchronize_srcu(). In addition, |
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* each CPU having an SRCU read-side critical section that extends beyond |
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* the return from synchronize_srcu() is guaranteed to have executed a |
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* full memory barrier after the beginning of synchronize_srcu() and before |
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* the beginning of that SRCU read-side critical section. Note that these |
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* guarantees include CPUs that are offline, idle, or executing in user mode, |
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* as well as CPUs that are executing in the kernel. |
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* |
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* Furthermore, if CPU A invoked synchronize_srcu(), which returned |
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* to its caller on CPU B, then both CPU A and CPU B are guaranteed |
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* to have executed a full memory barrier during the execution of |
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* synchronize_srcu(). This guarantee applies even if CPU A and CPU B |
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* are the same CPU, but again only if the system has more than one CPU. |
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* |
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* Of course, these memory-ordering guarantees apply only when |
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* synchronize_srcu(), srcu_read_lock(), and srcu_read_unlock() are |
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* passed the same srcu_struct structure. |
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*/ |
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void synchronize_srcu(struct srcu_struct *sp) |
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{ |
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__synchronize_srcu(sp, (rcu_gp_is_expedited() && !rcu_gp_is_normal()) |
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? SYNCHRONIZE_SRCU_EXP_TRYCOUNT |
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: SYNCHRONIZE_SRCU_TRYCOUNT); |
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} |
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EXPORT_SYMBOL_GPL(synchronize_srcu); |
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|
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/** |
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* synchronize_srcu_expedited - Brute-force SRCU grace period |
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* @sp: srcu_struct with which to synchronize. |
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* |
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* Wait for an SRCU grace period to elapse, but be more aggressive about |
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* spinning rather than blocking when waiting. |
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* |
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* Note that synchronize_srcu_expedited() has the same deadlock and |
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* memory-ordering properties as does synchronize_srcu(). |
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*/ |
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void synchronize_srcu_expedited(struct srcu_struct *sp) |
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{ |
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__synchronize_srcu(sp, SYNCHRONIZE_SRCU_EXP_TRYCOUNT); |
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} |
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EXPORT_SYMBOL_GPL(synchronize_srcu_expedited); |
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/** |
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* srcu_barrier - Wait until all in-flight call_srcu() callbacks complete. |
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* @sp: srcu_struct on which to wait for in-flight callbacks. |
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*/ |
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void srcu_barrier(struct srcu_struct *sp) |
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{ |
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synchronize_srcu(sp); |
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} |
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EXPORT_SYMBOL_GPL(srcu_barrier); |
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|
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/** |
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* srcu_batches_completed - return batches completed. |
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* @sp: srcu_struct on which to report batch completion. |
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* |
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* Report the number of batches, correlated with, but not necessarily |
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* precisely the same as, the number of grace periods that have elapsed. |
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*/ |
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unsigned long srcu_batches_completed(struct srcu_struct *sp) |
|
{ |
|
return sp->completed; |
|
} |
|
EXPORT_SYMBOL_GPL(srcu_batches_completed); |
|
|
|
#define SRCU_CALLBACK_BATCH 10 |
|
#define SRCU_INTERVAL 1 |
|
|
|
/* |
|
* Move any new SRCU callbacks to the first stage of the SRCU grace |
|
* period pipeline. |
|
*/ |
|
static void srcu_collect_new(struct srcu_struct *sp) |
|
{ |
|
if (!rcu_batch_empty(&sp->batch_queue)) { |
|
spin_lock_irq(&sp->queue_lock); |
|
rcu_batch_move(&sp->batch_check0, &sp->batch_queue); |
|
spin_unlock_irq(&sp->queue_lock); |
|
} |
|
} |
|
|
|
/* |
|
* Core SRCU state machine. Advance callbacks from ->batch_check0 to |
|
* ->batch_check1 and then to ->batch_done as readers drain. |
|
*/ |
|
static void srcu_advance_batches(struct srcu_struct *sp, int trycount) |
|
{ |
|
int idx = 1 ^ (sp->completed & 1); |
|
|
|
/* |
|
* Because readers might be delayed for an extended period after |
|
* fetching ->completed for their index, at any point in time there |
|
* might well be readers using both idx=0 and idx=1. We therefore |
|
* need to wait for readers to clear from both index values before |
|
* invoking a callback. |
|
*/ |
|
|
|
if (rcu_batch_empty(&sp->batch_check0) && |
|
rcu_batch_empty(&sp->batch_check1)) |
|
return; /* no callbacks need to be advanced */ |
|
|
|
if (!try_check_zero(sp, idx, trycount)) |
|
return; /* failed to advance, will try after SRCU_INTERVAL */ |
|
|
|
/* |
|
* The callbacks in ->batch_check1 have already done with their |
|
* first zero check and flip back when they were enqueued on |
|
* ->batch_check0 in a previous invocation of srcu_advance_batches(). |
|
* (Presumably try_check_zero() returned false during that |
|
* invocation, leaving the callbacks stranded on ->batch_check1.) |
|
* They are therefore ready to invoke, so move them to ->batch_done. |
|
*/ |
|
rcu_batch_move(&sp->batch_done, &sp->batch_check1); |
|
|
|
if (rcu_batch_empty(&sp->batch_check0)) |
|
return; /* no callbacks need to be advanced */ |
|
srcu_flip(sp); |
|
|
|
/* |
|
* The callbacks in ->batch_check0 just finished their |
|
* first check zero and flip, so move them to ->batch_check1 |
|
* for future checking on the other idx. |
|
*/ |
|
rcu_batch_move(&sp->batch_check1, &sp->batch_check0); |
|
|
|
/* |
|
* SRCU read-side critical sections are normally short, so check |
|
* at least twice in quick succession after a flip. |
|
*/ |
|
trycount = trycount < 2 ? 2 : trycount; |
|
if (!try_check_zero(sp, idx^1, trycount)) |
|
return; /* failed to advance, will try after SRCU_INTERVAL */ |
|
|
|
/* |
|
* The callbacks in ->batch_check1 have now waited for all |
|
* pre-existing readers using both idx values. They are therefore |
|
* ready to invoke, so move them to ->batch_done. |
|
*/ |
|
rcu_batch_move(&sp->batch_done, &sp->batch_check1); |
|
} |
|
|
|
/* |
|
* Invoke a limited number of SRCU callbacks that have passed through |
|
* their grace period. If there are more to do, SRCU will reschedule |
|
* the workqueue. |
|
*/ |
|
static void srcu_invoke_callbacks(struct srcu_struct *sp) |
|
{ |
|
int i; |
|
struct rcu_head *head; |
|
|
|
for (i = 0; i < SRCU_CALLBACK_BATCH; i++) { |
|
head = rcu_batch_dequeue(&sp->batch_done); |
|
if (!head) |
|
break; |
|
local_bh_disable(); |
|
head->func(head); |
|
local_bh_enable(); |
|
} |
|
} |
|
|
|
/* |
|
* Finished one round of SRCU grace period. Start another if there are |
|
* more SRCU callbacks queued, otherwise put SRCU into not-running state. |
|
*/ |
|
static void srcu_reschedule(struct srcu_struct *sp) |
|
{ |
|
bool pending = true; |
|
|
|
if (rcu_batch_empty(&sp->batch_done) && |
|
rcu_batch_empty(&sp->batch_check1) && |
|
rcu_batch_empty(&sp->batch_check0) && |
|
rcu_batch_empty(&sp->batch_queue)) { |
|
spin_lock_irq(&sp->queue_lock); |
|
if (rcu_batch_empty(&sp->batch_done) && |
|
rcu_batch_empty(&sp->batch_check1) && |
|
rcu_batch_empty(&sp->batch_check0) && |
|
rcu_batch_empty(&sp->batch_queue)) { |
|
sp->running = false; |
|
pending = false; |
|
} |
|
spin_unlock_irq(&sp->queue_lock); |
|
} |
|
|
|
if (pending) |
|
queue_delayed_work(system_power_efficient_wq, |
|
&sp->work, SRCU_INTERVAL); |
|
} |
|
|
|
/* |
|
* This is the work-queue function that handles SRCU grace periods. |
|
*/ |
|
void process_srcu(struct work_struct *work) |
|
{ |
|
struct srcu_struct *sp; |
|
|
|
sp = container_of(work, struct srcu_struct, work.work); |
|
|
|
srcu_collect_new(sp); |
|
srcu_advance_batches(sp, 1); |
|
srcu_invoke_callbacks(sp); |
|
srcu_reschedule(sp); |
|
} |
|
EXPORT_SYMBOL_GPL(process_srcu);
|
|
|