Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
555
kernel/workqueue.c
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555
kernel/workqueue.c
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@@ -0,0 +1,555 @@
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/*
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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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#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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/*
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* The per-CPU workqueue (if single thread, we always use cpu 0's).
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*
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* The sequence counters are for flush_scheduled_work(). It wants to wait
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* until until all currently-scheduled works are completed, but it doesn't
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* want to be livelocked by new, incoming ones. So it waits until
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* remove_sequence is >= the insert_sequence which pertained when
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* flush_scheduled_work() was called.
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*/
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struct cpu_workqueue_struct {
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spinlock_t lock;
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long remove_sequence; /* Least-recently added (next to run) */
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long insert_sequence; /* Next to add */
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struct list_head worklist;
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wait_queue_head_t more_work;
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wait_queue_head_t work_done;
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struct workqueue_struct *wq;
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task_t *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[NR_CPUS];
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const char *name;
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struct list_head list; /* Empty if single thread */
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};
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/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
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threads to each one as cpus come/go. */
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static DEFINE_SPINLOCK(workqueue_lock);
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static LIST_HEAD(workqueues);
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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 list_empty(&wq->list);
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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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work->wq_data = cwq;
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list_add_tail(&work->entry, &cwq->worklist);
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cwq->insert_sequence++;
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wake_up(&cwq->more_work);
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spin_unlock_irqrestore(&cwq->lock, flags);
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}
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/*
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* Queue work on a workqueue. Return non-zero if it was successfully
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* added.
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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 fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
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{
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int ret = 0, cpu = get_cpu();
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if (!test_and_set_bit(0, &work->pending)) {
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if (unlikely(is_single_threaded(wq)))
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cpu = 0;
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BUG_ON(!list_empty(&work->entry));
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__queue_work(wq->cpu_wq + cpu, work);
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ret = 1;
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}
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put_cpu();
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return ret;
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}
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static void delayed_work_timer_fn(unsigned long __data)
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{
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struct work_struct *work = (struct work_struct *)__data;
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struct workqueue_struct *wq = work->wq_data;
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int cpu = smp_processor_id();
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if (unlikely(is_single_threaded(wq)))
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cpu = 0;
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__queue_work(wq->cpu_wq + cpu, work);
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}
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int fastcall queue_delayed_work(struct workqueue_struct *wq,
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struct work_struct *work, unsigned long delay)
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{
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int ret = 0;
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struct timer_list *timer = &work->timer;
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if (!test_and_set_bit(0, &work->pending)) {
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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 wq for the moment, for the timer_fn */
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work->wq_data = wq;
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timer->expires = jiffies + delay;
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timer->data = (unsigned long)work;
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timer->function = delayed_work_timer_fn;
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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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static inline void run_workqueue(struct cpu_workqueue_struct *cwq)
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{
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unsigned long flags;
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/*
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* Keep taking off work from the queue until
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* done.
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*/
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spin_lock_irqsave(&cwq->lock, flags);
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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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void (*f) (void *) = work->func;
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void *data = work->data;
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list_del_init(cwq->worklist.next);
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spin_unlock_irqrestore(&cwq->lock, flags);
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BUG_ON(work->wq_data != cwq);
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clear_bit(0, &work->pending);
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f(data);
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spin_lock_irqsave(&cwq->lock, flags);
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cwq->remove_sequence++;
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wake_up(&cwq->work_done);
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}
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cwq->run_depth--;
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spin_unlock_irqrestore(&cwq->lock, flags);
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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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DECLARE_WAITQUEUE(wait, current);
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struct k_sigaction sa;
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sigset_t blocked;
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current->flags |= PF_NOFREEZE;
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set_user_nice(current, -5);
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/* Block and flush all signals */
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sigfillset(&blocked);
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sigprocmask(SIG_BLOCK, &blocked, NULL);
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flush_signals(current);
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/* SIG_IGN makes children autoreap: see do_notify_parent(). */
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sa.sa.sa_handler = SIG_IGN;
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sa.sa.sa_flags = 0;
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siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
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do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
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set_current_state(TASK_INTERRUPTIBLE);
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while (!kthread_should_stop()) {
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add_wait_queue(&cwq->more_work, &wait);
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if (list_empty(&cwq->worklist))
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schedule();
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else
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__set_current_state(TASK_RUNNING);
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remove_wait_queue(&cwq->more_work, &wait);
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if (!list_empty(&cwq->worklist))
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run_workqueue(cwq);
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set_current_state(TASK_INTERRUPTIBLE);
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}
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
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{
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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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} else {
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DEFINE_WAIT(wait);
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long sequence_needed;
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spin_lock_irq(&cwq->lock);
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sequence_needed = cwq->insert_sequence;
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while (sequence_needed - cwq->remove_sequence > 0) {
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prepare_to_wait(&cwq->work_done, &wait,
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TASK_UNINTERRUPTIBLE);
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spin_unlock_irq(&cwq->lock);
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schedule();
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spin_lock_irq(&cwq->lock);
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}
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finish_wait(&cwq->work_done, &wait);
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spin_unlock_irq(&cwq->lock);
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}
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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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*
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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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* This function will sample each workqueue's current insert_sequence number and
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* will sleep until the head sequence is greater than or equal to that. This
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* means that we sleep until all works which were queued on entry have been
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* handled, 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 fastcall flush_workqueue(struct workqueue_struct *wq)
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{
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might_sleep();
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if (is_single_threaded(wq)) {
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/* Always use cpu 0's area. */
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flush_cpu_workqueue(wq->cpu_wq + 0);
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} else {
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int cpu;
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lock_cpu_hotplug();
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for_each_online_cpu(cpu)
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flush_cpu_workqueue(wq->cpu_wq + cpu);
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unlock_cpu_hotplug();
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}
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}
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static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
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int cpu)
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{
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struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
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struct task_struct *p;
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spin_lock_init(&cwq->lock);
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cwq->wq = wq;
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cwq->thread = NULL;
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cwq->insert_sequence = 0;
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cwq->remove_sequence = 0;
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INIT_LIST_HEAD(&cwq->worklist);
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init_waitqueue_head(&cwq->more_work);
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init_waitqueue_head(&cwq->work_done);
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if (is_single_threaded(wq))
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p = kthread_create(worker_thread, cwq, "%s", wq->name);
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else
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p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu);
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if (IS_ERR(p))
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return NULL;
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cwq->thread = p;
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return p;
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}
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struct workqueue_struct *__create_workqueue(const char *name,
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int singlethread)
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{
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int cpu, destroy = 0;
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struct workqueue_struct *wq;
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struct task_struct *p;
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BUG_ON(strlen(name) > 10);
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wq = kmalloc(sizeof(*wq), GFP_KERNEL);
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if (!wq)
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return NULL;
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memset(wq, 0, sizeof(*wq));
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wq->name = name;
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/* We don't need the distraction of CPUs appearing and vanishing. */
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lock_cpu_hotplug();
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if (singlethread) {
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INIT_LIST_HEAD(&wq->list);
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p = create_workqueue_thread(wq, 0);
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if (!p)
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destroy = 1;
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else
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wake_up_process(p);
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} else {
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spin_lock(&workqueue_lock);
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list_add(&wq->list, &workqueues);
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spin_unlock(&workqueue_lock);
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for_each_online_cpu(cpu) {
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p = create_workqueue_thread(wq, cpu);
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if (p) {
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kthread_bind(p, cpu);
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wake_up_process(p);
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} else
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destroy = 1;
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}
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}
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unlock_cpu_hotplug();
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/*
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* Was there any error during startup? If yes then clean up:
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*/
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if (destroy) {
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destroy_workqueue(wq);
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wq = NULL;
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}
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return wq;
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}
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static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
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{
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struct cpu_workqueue_struct *cwq;
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unsigned long flags;
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struct task_struct *p;
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cwq = wq->cpu_wq + cpu;
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spin_lock_irqsave(&cwq->lock, flags);
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p = cwq->thread;
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cwq->thread = NULL;
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spin_unlock_irqrestore(&cwq->lock, flags);
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if (p)
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kthread_stop(p);
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}
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void destroy_workqueue(struct workqueue_struct *wq)
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{
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int cpu;
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flush_workqueue(wq);
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/* We don't need the distraction of CPUs appearing and vanishing. */
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lock_cpu_hotplug();
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if (is_single_threaded(wq))
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cleanup_workqueue_thread(wq, 0);
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else {
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for_each_online_cpu(cpu)
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cleanup_workqueue_thread(wq, cpu);
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spin_lock(&workqueue_lock);
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list_del(&wq->list);
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spin_unlock(&workqueue_lock);
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}
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unlock_cpu_hotplug();
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kfree(wq);
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}
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static struct workqueue_struct *keventd_wq;
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int fastcall schedule_work(struct work_struct *work)
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{
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return queue_work(keventd_wq, work);
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}
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int fastcall schedule_delayed_work(struct work_struct *work, unsigned long delay)
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{
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return queue_delayed_work(keventd_wq, work, delay);
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}
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int schedule_delayed_work_on(int cpu,
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struct work_struct *work, unsigned long delay)
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{
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int ret = 0;
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struct timer_list *timer = &work->timer;
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if (!test_and_set_bit(0, &work->pending)) {
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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 keventd_wq for the moment, for the timer_fn */
|
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work->wq_data = keventd_wq;
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timer->expires = jiffies + delay;
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timer->data = (unsigned long)work;
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timer->function = delayed_work_timer_fn;
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add_timer_on(timer, 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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||||
|
||||
void flush_scheduled_work(void)
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||||
{
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||||
flush_workqueue(keventd_wq);
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}
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||||
|
||||
/**
|
||||
* cancel_rearming_delayed_workqueue - reliably kill off a delayed
|
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* work whose handler rearms the delayed work.
|
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* @wq: the controlling workqueue structure
|
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* @work: the delayed work struct
|
||||
*/
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static void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
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struct work_struct *work)
|
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{
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while (!cancel_delayed_work(work))
|
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flush_workqueue(wq);
|
||||
}
|
||||
|
||||
/**
|
||||
* cancel_rearming_delayed_work - reliably kill off a delayed keventd
|
||||
* work whose handler rearms the delayed work.
|
||||
* @work: the delayed work struct
|
||||
*/
|
||||
void cancel_rearming_delayed_work(struct work_struct *work)
|
||||
{
|
||||
cancel_rearming_delayed_workqueue(keventd_wq, work);
|
||||
}
|
||||
EXPORT_SYMBOL(cancel_rearming_delayed_work);
|
||||
|
||||
int keventd_up(void)
|
||||
{
|
||||
return keventd_wq != NULL;
|
||||
}
|
||||
|
||||
int current_is_keventd(void)
|
||||
{
|
||||
struct cpu_workqueue_struct *cwq;
|
||||
int cpu = smp_processor_id(); /* preempt-safe: keventd is per-cpu */
|
||||
int ret = 0;
|
||||
|
||||
BUG_ON(!keventd_wq);
|
||||
|
||||
cwq = keventd_wq->cpu_wq + cpu;
|
||||
if (current == cwq->thread)
|
||||
ret = 1;
|
||||
|
||||
return ret;
|
||||
|
||||
}
|
||||
|
||||
#ifdef CONFIG_HOTPLUG_CPU
|
||||
/* Take the work from this (downed) CPU. */
|
||||
static void take_over_work(struct workqueue_struct *wq, unsigned int cpu)
|
||||
{
|
||||
struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
|
||||
LIST_HEAD(list);
|
||||
struct work_struct *work;
|
||||
|
||||
spin_lock_irq(&cwq->lock);
|
||||
list_splice_init(&cwq->worklist, &list);
|
||||
|
||||
while (!list_empty(&list)) {
|
||||
printk("Taking work for %s\n", wq->name);
|
||||
work = list_entry(list.next,struct work_struct,entry);
|
||||
list_del(&work->entry);
|
||||
__queue_work(wq->cpu_wq + smp_processor_id(), work);
|
||||
}
|
||||
spin_unlock_irq(&cwq->lock);
|
||||
}
|
||||
|
||||
/* We're holding the cpucontrol mutex here */
|
||||
static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
|
||||
unsigned long action,
|
||||
void *hcpu)
|
||||
{
|
||||
unsigned int hotcpu = (unsigned long)hcpu;
|
||||
struct workqueue_struct *wq;
|
||||
|
||||
switch (action) {
|
||||
case CPU_UP_PREPARE:
|
||||
/* Create a new workqueue thread for it. */
|
||||
list_for_each_entry(wq, &workqueues, list) {
|
||||
if (create_workqueue_thread(wq, hotcpu) < 0) {
|
||||
printk("workqueue for %i failed\n", hotcpu);
|
||||
return NOTIFY_BAD;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case CPU_ONLINE:
|
||||
/* Kick off worker threads. */
|
||||
list_for_each_entry(wq, &workqueues, list) {
|
||||
kthread_bind(wq->cpu_wq[hotcpu].thread, hotcpu);
|
||||
wake_up_process(wq->cpu_wq[hotcpu].thread);
|
||||
}
|
||||
break;
|
||||
|
||||
case CPU_UP_CANCELED:
|
||||
list_for_each_entry(wq, &workqueues, list) {
|
||||
/* Unbind so it can run. */
|
||||
kthread_bind(wq->cpu_wq[hotcpu].thread,
|
||||
smp_processor_id());
|
||||
cleanup_workqueue_thread(wq, hotcpu);
|
||||
}
|
||||
break;
|
||||
|
||||
case CPU_DEAD:
|
||||
list_for_each_entry(wq, &workqueues, list)
|
||||
cleanup_workqueue_thread(wq, hotcpu);
|
||||
list_for_each_entry(wq, &workqueues, list)
|
||||
take_over_work(wq, hotcpu);
|
||||
break;
|
||||
}
|
||||
|
||||
return NOTIFY_OK;
|
||||
}
|
||||
#endif
|
||||
|
||||
void init_workqueues(void)
|
||||
{
|
||||
hotcpu_notifier(workqueue_cpu_callback, 0);
|
||||
keventd_wq = create_workqueue("events");
|
||||
BUG_ON(!keventd_wq);
|
||||
}
|
||||
|
||||
EXPORT_SYMBOL_GPL(__create_workqueue);
|
||||
EXPORT_SYMBOL_GPL(queue_work);
|
||||
EXPORT_SYMBOL_GPL(queue_delayed_work);
|
||||
EXPORT_SYMBOL_GPL(flush_workqueue);
|
||||
EXPORT_SYMBOL_GPL(destroy_workqueue);
|
||||
|
||||
EXPORT_SYMBOL(schedule_work);
|
||||
EXPORT_SYMBOL(schedule_delayed_work);
|
||||
EXPORT_SYMBOL(schedule_delayed_work_on);
|
||||
EXPORT_SYMBOL(flush_scheduled_work);
|
||||
Reference in New Issue
Block a user