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878 lines
22 KiB
878 lines
22 KiB
/*
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* linux/kernel/workqueue.c
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*
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* Generic mechanism for defining kernel helper threads for running
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* arbitrary tasks in process context.
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*
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* Started by Ingo Molnar, Copyright (C) 2002
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*
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* Derived from the taskqueue/keventd code by:
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*
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* David Woodhouse <dwmw2@infradead.org>
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* Andrew Morton <andrewm@uow.edu.au>
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* Kai Petzke <wpp@marie.physik.tu-berlin.de>
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* Theodore Ts'o <tytso@mit.edu>
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*
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* Made to use alloc_percpu by Christoph Lameter <clameter@sgi.com>.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/signal.h>
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#include <linux/completion.h>
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#include <linux/workqueue.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/kthread.h>
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#include <linux/hardirq.h>
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#include <linux/mempolicy.h>
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#include <linux/freezer.h>
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#include <linux/kallsyms.h>
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#include <linux/debug_locks.h>
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#include <linux/lockdep.h>
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/*
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* The per-CPU workqueue (if single thread, we always use the first
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* possible cpu).
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*/
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struct cpu_workqueue_struct {
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spinlock_t lock;
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struct list_head worklist;
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wait_queue_head_t more_work;
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struct work_struct *current_work;
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struct workqueue_struct *wq;
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struct task_struct *thread;
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int run_depth; /* Detect run_workqueue() recursion depth */
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} ____cacheline_aligned;
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/*
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* The externally visible workqueue abstraction is an array of
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* per-CPU workqueues:
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*/
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struct workqueue_struct {
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struct cpu_workqueue_struct *cpu_wq;
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struct list_head list;
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const char *name;
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int singlethread;
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int freezeable; /* Freeze threads during suspend */
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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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};
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/* Serializes the accesses to the list of workqueues. */
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static DEFINE_SPINLOCK(workqueue_lock);
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static LIST_HEAD(workqueues);
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static int singlethread_cpu __read_mostly;
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static cpumask_t cpu_singlethread_map __read_mostly;
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/*
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* _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD
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* flushes cwq->worklist. This means that flush_workqueue/wait_on_work
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* which comes in between can't use for_each_online_cpu(). We could
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* use cpu_possible_map, the cpumask below is more a documentation
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* than optimization.
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*/
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static cpumask_t cpu_populated_map __read_mostly;
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/* If it's single threaded, it isn't in the list of workqueues. */
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static inline int is_single_threaded(struct workqueue_struct *wq)
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{
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return wq->singlethread;
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}
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static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
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{
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return is_single_threaded(wq)
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? &cpu_singlethread_map : &cpu_populated_map;
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}
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static
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struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
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{
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if (unlikely(is_single_threaded(wq)))
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cpu = singlethread_cpu;
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return per_cpu_ptr(wq->cpu_wq, cpu);
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}
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/*
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* Set the workqueue on which a work item is to be run
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* - Must *only* be called if the pending flag is set
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*/
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static inline void set_wq_data(struct work_struct *work,
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struct cpu_workqueue_struct *cwq)
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{
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unsigned long new;
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BUG_ON(!work_pending(work));
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new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
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new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
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atomic_long_set(&work->data, new);
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}
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static inline
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struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
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{
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return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
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}
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static void insert_work(struct cpu_workqueue_struct *cwq,
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struct work_struct *work, int tail)
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{
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set_wq_data(work, cwq);
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/*
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* Ensure that we get the right work->data if we see the
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* result of list_add() below, see try_to_grab_pending().
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*/
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smp_wmb();
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if (tail)
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list_add_tail(&work->entry, &cwq->worklist);
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else
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list_add(&work->entry, &cwq->worklist);
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wake_up(&cwq->more_work);
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}
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/* Preempt must be disabled. */
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static void __queue_work(struct cpu_workqueue_struct *cwq,
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struct work_struct *work)
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{
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unsigned long flags;
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spin_lock_irqsave(&cwq->lock, flags);
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insert_work(cwq, work, 1);
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spin_unlock_irqrestore(&cwq->lock, flags);
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}
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/**
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* queue_work - queue work on a workqueue
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* @wq: workqueue to use
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* @work: work to queue
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*
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* We queue the work to the CPU it was submitted, but there is no
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* guarantee that it will be processed by that CPU.
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*/
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int queue_work(struct workqueue_struct *wq, struct work_struct *work)
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{
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int ret = 0;
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if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
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BUG_ON(!list_empty(&work->entry));
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__queue_work(wq_per_cpu(wq, get_cpu()), work);
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put_cpu();
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ret = 1;
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(queue_work);
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static void delayed_work_timer_fn(unsigned long __data)
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{
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struct delayed_work *dwork = (struct delayed_work *)__data;
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struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
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struct workqueue_struct *wq = cwq->wq;
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__queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
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}
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/**
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* queue_delayed_work - queue work on a workqueue after delay
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* @wq: workqueue to use
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* @dwork: delayable work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*/
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int queue_delayed_work(struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay)
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{
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timer_stats_timer_set_start_info(&dwork->timer);
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if (delay == 0)
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return queue_work(wq, &dwork->work);
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return queue_delayed_work_on(-1, wq, dwork, delay);
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}
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EXPORT_SYMBOL_GPL(queue_delayed_work);
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/**
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* queue_delayed_work_on - queue work on specific CPU after delay
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* @cpu: CPU number to execute work on
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* @wq: workqueue to use
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* @dwork: work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*/
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int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay)
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{
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int ret = 0;
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struct timer_list *timer = &dwork->timer;
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struct work_struct *work = &dwork->work;
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if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
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BUG_ON(timer_pending(timer));
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BUG_ON(!list_empty(&work->entry));
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/* This stores cwq for the moment, for the timer_fn */
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set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
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timer->expires = jiffies + delay;
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timer->data = (unsigned long)dwork;
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timer->function = delayed_work_timer_fn;
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if (unlikely(cpu >= 0))
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add_timer_on(timer, cpu);
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else
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add_timer(timer);
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ret = 1;
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(queue_delayed_work_on);
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static void run_workqueue(struct cpu_workqueue_struct *cwq)
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{
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spin_lock_irq(&cwq->lock);
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cwq->run_depth++;
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if (cwq->run_depth > 3) {
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/* morton gets to eat his hat */
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printk("%s: recursion depth exceeded: %d\n",
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__FUNCTION__, cwq->run_depth);
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dump_stack();
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}
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while (!list_empty(&cwq->worklist)) {
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struct work_struct *work = list_entry(cwq->worklist.next,
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struct work_struct, entry);
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work_func_t f = work->func;
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#ifdef CONFIG_LOCKDEP
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/*
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* It is permissible to free the struct work_struct
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* from inside the function that is called from it,
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* this we need to take into account for lockdep too.
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* To avoid bogus "held lock freed" warnings as well
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* as problems when looking into work->lockdep_map,
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* make a copy and use that here.
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*/
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struct lockdep_map lockdep_map = work->lockdep_map;
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#endif
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cwq->current_work = work;
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list_del_init(cwq->worklist.next);
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spin_unlock_irq(&cwq->lock);
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BUG_ON(get_wq_data(work) != cwq);
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work_clear_pending(work);
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lock_acquire(&cwq->wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
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lock_acquire(&lockdep_map, 0, 0, 0, 2, _THIS_IP_);
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f(work);
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lock_release(&lockdep_map, 1, _THIS_IP_);
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lock_release(&cwq->wq->lockdep_map, 1, _THIS_IP_);
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if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
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printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
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"%s/0x%08x/%d\n",
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current->comm, preempt_count(),
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task_pid_nr(current));
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printk(KERN_ERR " last function: ");
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print_symbol("%s\n", (unsigned long)f);
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debug_show_held_locks(current);
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dump_stack();
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}
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spin_lock_irq(&cwq->lock);
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cwq->current_work = NULL;
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}
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cwq->run_depth--;
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spin_unlock_irq(&cwq->lock);
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}
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static int worker_thread(void *__cwq)
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{
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struct cpu_workqueue_struct *cwq = __cwq;
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DEFINE_WAIT(wait);
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if (cwq->wq->freezeable)
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set_freezable();
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set_user_nice(current, -5);
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for (;;) {
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prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
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if (!freezing(current) &&
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!kthread_should_stop() &&
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list_empty(&cwq->worklist))
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schedule();
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finish_wait(&cwq->more_work, &wait);
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try_to_freeze();
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if (kthread_should_stop())
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break;
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run_workqueue(cwq);
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}
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return 0;
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}
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struct wq_barrier {
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struct work_struct work;
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struct completion done;
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};
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static void wq_barrier_func(struct work_struct *work)
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{
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struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
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complete(&barr->done);
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}
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static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
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struct wq_barrier *barr, int tail)
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{
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INIT_WORK(&barr->work, wq_barrier_func);
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__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
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init_completion(&barr->done);
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insert_work(cwq, &barr->work, tail);
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}
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static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
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{
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int active;
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if (cwq->thread == current) {
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/*
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* Probably keventd trying to flush its own queue. So simply run
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* it by hand rather than deadlocking.
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*/
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run_workqueue(cwq);
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active = 1;
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} else {
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struct wq_barrier barr;
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active = 0;
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spin_lock_irq(&cwq->lock);
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if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
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insert_wq_barrier(cwq, &barr, 1);
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active = 1;
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}
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spin_unlock_irq(&cwq->lock);
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if (active)
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wait_for_completion(&barr.done);
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}
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return active;
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}
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/**
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* flush_workqueue - ensure that any scheduled work has run to completion.
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* @wq: workqueue to flush
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*
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* Forces execution of the workqueue and blocks until its completion.
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* This is typically used in driver shutdown handlers.
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*
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* We sleep until all works which were queued on entry have been handled,
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* but we are not livelocked by new incoming ones.
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*
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* This function used to run the workqueues itself. Now we just wait for the
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* helper threads to do it.
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*/
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void flush_workqueue(struct workqueue_struct *wq)
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{
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const cpumask_t *cpu_map = wq_cpu_map(wq);
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int cpu;
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might_sleep();
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lock_acquire(&wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
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lock_release(&wq->lockdep_map, 1, _THIS_IP_);
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for_each_cpu_mask(cpu, *cpu_map)
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flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
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}
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EXPORT_SYMBOL_GPL(flush_workqueue);
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/*
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* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
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* so this work can't be re-armed in any way.
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*/
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static int try_to_grab_pending(struct work_struct *work)
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{
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struct cpu_workqueue_struct *cwq;
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int ret = -1;
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if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
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return 0;
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/*
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* The queueing is in progress, or it is already queued. Try to
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* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
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*/
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cwq = get_wq_data(work);
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if (!cwq)
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return ret;
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spin_lock_irq(&cwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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* This work is queued, but perhaps we locked the wrong cwq.
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* In that case we must see the new value after rmb(), see
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* insert_work()->wmb().
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*/
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smp_rmb();
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if (cwq == get_wq_data(work)) {
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list_del_init(&work->entry);
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ret = 1;
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}
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}
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spin_unlock_irq(&cwq->lock);
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return ret;
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}
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static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
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struct work_struct *work)
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{
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struct wq_barrier barr;
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int running = 0;
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spin_lock_irq(&cwq->lock);
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if (unlikely(cwq->current_work == work)) {
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insert_wq_barrier(cwq, &barr, 0);
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running = 1;
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}
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spin_unlock_irq(&cwq->lock);
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if (unlikely(running))
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wait_for_completion(&barr.done);
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}
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static void wait_on_work(struct work_struct *work)
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{
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struct cpu_workqueue_struct *cwq;
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struct workqueue_struct *wq;
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const cpumask_t *cpu_map;
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int cpu;
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might_sleep();
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lock_acquire(&work->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
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lock_release(&work->lockdep_map, 1, _THIS_IP_);
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cwq = get_wq_data(work);
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if (!cwq)
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return;
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wq = cwq->wq;
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cpu_map = wq_cpu_map(wq);
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for_each_cpu_mask(cpu, *cpu_map)
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wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
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}
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static int __cancel_work_timer(struct work_struct *work,
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struct timer_list* timer)
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{
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int ret;
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do {
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ret = (timer && likely(del_timer(timer)));
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if (!ret)
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ret = try_to_grab_pending(work);
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wait_on_work(work);
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} while (unlikely(ret < 0));
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work_clear_pending(work);
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return ret;
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}
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/**
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* cancel_work_sync - block until a work_struct's callback has terminated
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* @work: the work which is to be flushed
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*
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* Returns true if @work was pending.
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*
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* cancel_work_sync() will cancel the work if it is queued. If the work's
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* callback appears to be running, cancel_work_sync() will block until it
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* has completed.
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*
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* It is possible to use this function if the work re-queues itself. It can
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* cancel the work even if it migrates to another workqueue, however in that
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* case it only guarantees that work->func() has completed on the last queued
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* workqueue.
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*
|
|
* cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
|
|
* pending, otherwise it goes into a busy-wait loop until the timer expires.
|
|
*
|
|
* The caller must ensure that workqueue_struct on which this work was last
|
|
* queued can't be destroyed before this function returns.
|
|
*/
|
|
int cancel_work_sync(struct work_struct *work)
|
|
{
|
|
return __cancel_work_timer(work, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cancel_work_sync);
|
|
|
|
/**
|
|
* cancel_delayed_work_sync - reliably kill off a delayed work.
|
|
* @dwork: the delayed work struct
|
|
*
|
|
* Returns true if @dwork was pending.
|
|
*
|
|
* It is possible to use this function if @dwork rearms itself via queue_work()
|
|
* or queue_delayed_work(). See also the comment for cancel_work_sync().
|
|
*/
|
|
int cancel_delayed_work_sync(struct delayed_work *dwork)
|
|
{
|
|
return __cancel_work_timer(&dwork->work, &dwork->timer);
|
|
}
|
|
EXPORT_SYMBOL(cancel_delayed_work_sync);
|
|
|
|
static struct workqueue_struct *keventd_wq __read_mostly;
|
|
|
|
/**
|
|
* schedule_work - put work task in global workqueue
|
|
* @work: job to be done
|
|
*
|
|
* This puts a job in the kernel-global workqueue.
|
|
*/
|
|
int schedule_work(struct work_struct *work)
|
|
{
|
|
return queue_work(keventd_wq, work);
|
|
}
|
|
EXPORT_SYMBOL(schedule_work);
|
|
|
|
/**
|
|
* schedule_delayed_work - put work task in global workqueue after delay
|
|
* @dwork: job to be done
|
|
* @delay: number of jiffies to wait or 0 for immediate execution
|
|
*
|
|
* After waiting for a given time this puts a job in the kernel-global
|
|
* workqueue.
|
|
*/
|
|
int schedule_delayed_work(struct delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
timer_stats_timer_set_start_info(&dwork->timer);
|
|
return queue_delayed_work(keventd_wq, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL(schedule_delayed_work);
|
|
|
|
/**
|
|
* schedule_delayed_work_on - queue work in global workqueue on CPU after delay
|
|
* @cpu: cpu to use
|
|
* @dwork: job to be done
|
|
* @delay: number of jiffies to wait
|
|
*
|
|
* After waiting for a given time this puts a job in the kernel-global
|
|
* workqueue on the specified CPU.
|
|
*/
|
|
int schedule_delayed_work_on(int cpu,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL(schedule_delayed_work_on);
|
|
|
|
/**
|
|
* schedule_on_each_cpu - call a function on each online CPU from keventd
|
|
* @func: the function to call
|
|
*
|
|
* Returns zero on success.
|
|
* Returns -ve errno on failure.
|
|
*
|
|
* schedule_on_each_cpu() is very slow.
|
|
*/
|
|
int schedule_on_each_cpu(work_func_t func)
|
|
{
|
|
int cpu;
|
|
struct work_struct *works;
|
|
|
|
works = alloc_percpu(struct work_struct);
|
|
if (!works)
|
|
return -ENOMEM;
|
|
|
|
get_online_cpus();
|
|
for_each_online_cpu(cpu) {
|
|
struct work_struct *work = per_cpu_ptr(works, cpu);
|
|
|
|
INIT_WORK(work, func);
|
|
set_bit(WORK_STRUCT_PENDING, work_data_bits(work));
|
|
__queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work);
|
|
}
|
|
flush_workqueue(keventd_wq);
|
|
put_online_cpus();
|
|
free_percpu(works);
|
|
return 0;
|
|
}
|
|
|
|
void flush_scheduled_work(void)
|
|
{
|
|
flush_workqueue(keventd_wq);
|
|
}
|
|
EXPORT_SYMBOL(flush_scheduled_work);
|
|
|
|
/**
|
|
* execute_in_process_context - reliably execute the routine with user context
|
|
* @fn: the function to execute
|
|
* @ew: guaranteed storage for the execute work structure (must
|
|
* be available when the work executes)
|
|
*
|
|
* Executes the function immediately if process context is available,
|
|
* otherwise schedules the function for delayed execution.
|
|
*
|
|
* Returns: 0 - function was executed
|
|
* 1 - function was scheduled for execution
|
|
*/
|
|
int execute_in_process_context(work_func_t fn, struct execute_work *ew)
|
|
{
|
|
if (!in_interrupt()) {
|
|
fn(&ew->work);
|
|
return 0;
|
|
}
|
|
|
|
INIT_WORK(&ew->work, fn);
|
|
schedule_work(&ew->work);
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(execute_in_process_context);
|
|
|
|
int keventd_up(void)
|
|
{
|
|
return keventd_wq != NULL;
|
|
}
|
|
|
|
int current_is_keventd(void)
|
|
{
|
|
struct cpu_workqueue_struct *cwq;
|
|
int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */
|
|
int ret = 0;
|
|
|
|
BUG_ON(!keventd_wq);
|
|
|
|
cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
|
|
if (current == cwq->thread)
|
|
ret = 1;
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
static struct cpu_workqueue_struct *
|
|
init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
|
|
{
|
|
struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
|
|
|
|
cwq->wq = wq;
|
|
spin_lock_init(&cwq->lock);
|
|
INIT_LIST_HEAD(&cwq->worklist);
|
|
init_waitqueue_head(&cwq->more_work);
|
|
|
|
return cwq;
|
|
}
|
|
|
|
static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
|
|
{
|
|
struct workqueue_struct *wq = cwq->wq;
|
|
const char *fmt = is_single_threaded(wq) ? "%s" : "%s/%d";
|
|
struct task_struct *p;
|
|
|
|
p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
|
|
/*
|
|
* Nobody can add the work_struct to this cwq,
|
|
* if (caller is __create_workqueue)
|
|
* nobody should see this wq
|
|
* else // caller is CPU_UP_PREPARE
|
|
* cpu is not on cpu_online_map
|
|
* so we can abort safely.
|
|
*/
|
|
if (IS_ERR(p))
|
|
return PTR_ERR(p);
|
|
|
|
cwq->thread = p;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
|
|
{
|
|
struct task_struct *p = cwq->thread;
|
|
|
|
if (p != NULL) {
|
|
if (cpu >= 0)
|
|
kthread_bind(p, cpu);
|
|
wake_up_process(p);
|
|
}
|
|
}
|
|
|
|
struct workqueue_struct *__create_workqueue_key(const char *name,
|
|
int singlethread,
|
|
int freezeable,
|
|
struct lock_class_key *key,
|
|
const char *lock_name)
|
|
{
|
|
struct workqueue_struct *wq;
|
|
struct cpu_workqueue_struct *cwq;
|
|
int err = 0, cpu;
|
|
|
|
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
|
|
if (!wq)
|
|
return NULL;
|
|
|
|
wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
|
|
if (!wq->cpu_wq) {
|
|
kfree(wq);
|
|
return NULL;
|
|
}
|
|
|
|
wq->name = name;
|
|
lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
|
|
wq->singlethread = singlethread;
|
|
wq->freezeable = freezeable;
|
|
INIT_LIST_HEAD(&wq->list);
|
|
|
|
if (singlethread) {
|
|
cwq = init_cpu_workqueue(wq, singlethread_cpu);
|
|
err = create_workqueue_thread(cwq, singlethread_cpu);
|
|
start_workqueue_thread(cwq, -1);
|
|
} else {
|
|
get_online_cpus();
|
|
spin_lock(&workqueue_lock);
|
|
list_add(&wq->list, &workqueues);
|
|
spin_unlock(&workqueue_lock);
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
cwq = init_cpu_workqueue(wq, cpu);
|
|
if (err || !cpu_online(cpu))
|
|
continue;
|
|
err = create_workqueue_thread(cwq, cpu);
|
|
start_workqueue_thread(cwq, cpu);
|
|
}
|
|
put_online_cpus();
|
|
}
|
|
|
|
if (err) {
|
|
destroy_workqueue(wq);
|
|
wq = NULL;
|
|
}
|
|
return wq;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__create_workqueue_key);
|
|
|
|
static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
|
|
{
|
|
/*
|
|
* Our caller is either destroy_workqueue() or CPU_DEAD,
|
|
* get_online_cpus() protects cwq->thread.
|
|
*/
|
|
if (cwq->thread == NULL)
|
|
return;
|
|
|
|
lock_acquire(&cwq->wq->lockdep_map, 0, 0, 0, 2, _THIS_IP_);
|
|
lock_release(&cwq->wq->lockdep_map, 1, _THIS_IP_);
|
|
|
|
flush_cpu_workqueue(cwq);
|
|
/*
|
|
* If the caller is CPU_DEAD and cwq->worklist was not empty,
|
|
* a concurrent flush_workqueue() can insert a barrier after us.
|
|
* However, in that case run_workqueue() won't return and check
|
|
* kthread_should_stop() until it flushes all work_struct's.
|
|
* When ->worklist becomes empty it is safe to exit because no
|
|
* more work_structs can be queued on this cwq: flush_workqueue
|
|
* checks list_empty(), and a "normal" queue_work() can't use
|
|
* a dead CPU.
|
|
*/
|
|
kthread_stop(cwq->thread);
|
|
cwq->thread = NULL;
|
|
}
|
|
|
|
/**
|
|
* destroy_workqueue - safely terminate a workqueue
|
|
* @wq: target workqueue
|
|
*
|
|
* Safely destroy a workqueue. All work currently pending will be done first.
|
|
*/
|
|
void destroy_workqueue(struct workqueue_struct *wq)
|
|
{
|
|
const cpumask_t *cpu_map = wq_cpu_map(wq);
|
|
struct cpu_workqueue_struct *cwq;
|
|
int cpu;
|
|
|
|
get_online_cpus();
|
|
spin_lock(&workqueue_lock);
|
|
list_del(&wq->list);
|
|
spin_unlock(&workqueue_lock);
|
|
put_online_cpus();
|
|
|
|
for_each_cpu_mask(cpu, *cpu_map) {
|
|
cwq = per_cpu_ptr(wq->cpu_wq, cpu);
|
|
cleanup_workqueue_thread(cwq, cpu);
|
|
}
|
|
|
|
free_percpu(wq->cpu_wq);
|
|
kfree(wq);
|
|
}
|
|
EXPORT_SYMBOL_GPL(destroy_workqueue);
|
|
|
|
static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
unsigned int cpu = (unsigned long)hcpu;
|
|
struct cpu_workqueue_struct *cwq;
|
|
struct workqueue_struct *wq;
|
|
|
|
action &= ~CPU_TASKS_FROZEN;
|
|
|
|
switch (action) {
|
|
|
|
case CPU_UP_PREPARE:
|
|
cpu_set(cpu, cpu_populated_map);
|
|
}
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
cwq = per_cpu_ptr(wq->cpu_wq, cpu);
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
if (!create_workqueue_thread(cwq, cpu))
|
|
break;
|
|
printk(KERN_ERR "workqueue [%s] for %i failed\n",
|
|
wq->name, cpu);
|
|
return NOTIFY_BAD;
|
|
|
|
case CPU_ONLINE:
|
|
start_workqueue_thread(cwq, cpu);
|
|
break;
|
|
|
|
case CPU_UP_CANCELED:
|
|
start_workqueue_thread(cwq, -1);
|
|
case CPU_DEAD:
|
|
cleanup_workqueue_thread(cwq, cpu);
|
|
break;
|
|
}
|
|
}
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
void __init init_workqueues(void)
|
|
{
|
|
cpu_populated_map = cpu_online_map;
|
|
singlethread_cpu = first_cpu(cpu_possible_map);
|
|
cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);
|
|
hotcpu_notifier(workqueue_cpu_callback, 0);
|
|
keventd_wq = create_workqueue("events");
|
|
BUG_ON(!keventd_wq);
|
|
}
|
|
|