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-rw-r--r--kernel/workqueue.c555
1 files changed, 555 insertions, 0 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
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+/*
+ * linux/kernel/workqueue.c
+ *
+ * Generic mechanism for defining kernel helper threads for running
+ * arbitrary tasks in process context.
+ *
+ * Started by Ingo Molnar, Copyright (C) 2002
+ *
+ * Derived from the taskqueue/keventd code by:
+ *
+ * David Woodhouse <dwmw2@infradead.org>
+ * Andrew Morton <andrewm@uow.edu.au>
+ * Kai Petzke <wpp@marie.physik.tu-berlin.de>
+ * Theodore Ts'o <tytso@mit.edu>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/completion.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+
+/*
+ * The per-CPU workqueue (if single thread, we always use cpu 0's).
+ *
+ * The sequence counters are for flush_scheduled_work(). It wants to wait
+ * until until all currently-scheduled works are completed, but it doesn't
+ * want to be livelocked by new, incoming ones. So it waits until
+ * remove_sequence is >= the insert_sequence which pertained when
+ * flush_scheduled_work() was called.
+ */
+struct cpu_workqueue_struct {
+
+ spinlock_t lock;
+
+ long remove_sequence; /* Least-recently added (next to run) */
+ long insert_sequence; /* Next to add */
+
+ struct list_head worklist;
+ wait_queue_head_t more_work;
+ wait_queue_head_t work_done;
+
+ struct workqueue_struct *wq;
+ task_t *thread;
+
+ int run_depth; /* Detect run_workqueue() recursion depth */
+} ____cacheline_aligned;
+
+/*
+ * The externally visible workqueue abstraction is an array of
+ * per-CPU workqueues:
+ */
+struct workqueue_struct {
+ struct cpu_workqueue_struct cpu_wq[NR_CPUS];
+ const char *name;
+ struct list_head list; /* Empty if single thread */
+};
+
+/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
+ threads to each one as cpus come/go. */
+static DEFINE_SPINLOCK(workqueue_lock);
+static LIST_HEAD(workqueues);
+
+/* If it's single threaded, it isn't in the list of workqueues. */
+static inline int is_single_threaded(struct workqueue_struct *wq)
+{
+ return list_empty(&wq->list);
+}
+
+/* Preempt must be disabled. */
+static void __queue_work(struct cpu_workqueue_struct *cwq,
+ struct work_struct *work)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cwq->lock, flags);
+ work->wq_data = cwq;
+ list_add_tail(&work->entry, &cwq->worklist);
+ cwq->insert_sequence++;
+ wake_up(&cwq->more_work);
+ spin_unlock_irqrestore(&cwq->lock, flags);
+}
+
+/*
+ * Queue work on a workqueue. Return non-zero if it was successfully
+ * added.
+ *
+ * We queue the work to the CPU it was submitted, but there is no
+ * guarantee that it will be processed by that CPU.
+ */
+int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
+{
+ int ret = 0, cpu = get_cpu();
+
+ if (!test_and_set_bit(0, &work->pending)) {
+ if (unlikely(is_single_threaded(wq)))
+ cpu = 0;
+ BUG_ON(!list_empty(&work->entry));
+ __queue_work(wq->cpu_wq + cpu, work);
+ ret = 1;
+ }
+ put_cpu();
+ return ret;
+}
+
+static void delayed_work_timer_fn(unsigned long __data)
+{
+ struct work_struct *work = (struct work_struct *)__data;
+ struct workqueue_struct *wq = work->wq_data;
+ int cpu = smp_processor_id();
+
+ if (unlikely(is_single_threaded(wq)))
+ cpu = 0;
+
+ __queue_work(wq->cpu_wq + cpu, work);
+}
+
+int fastcall queue_delayed_work(struct workqueue_struct *wq,
+ struct work_struct *work, unsigned long delay)
+{
+ int ret = 0;
+ struct timer_list *timer = &work->timer;
+
+ if (!test_and_set_bit(0, &work->pending)) {
+ BUG_ON(timer_pending(timer));
+ BUG_ON(!list_empty(&work->entry));
+
+ /* This stores wq for the moment, for the timer_fn */
+ work->wq_data = wq;
+ timer->expires = jiffies + delay;
+ timer->data = (unsigned long)work;
+ timer->function = delayed_work_timer_fn;
+ add_timer(timer);
+ ret = 1;
+ }
+ return ret;
+}
+
+static inline void run_workqueue(struct cpu_workqueue_struct *cwq)
+{
+ unsigned long flags;
+
+ /*
+ * Keep taking off work from the queue until
+ * done.
+ */
+ spin_lock_irqsave(&cwq->lock, flags);
+ cwq->run_depth++;
+ if (cwq->run_depth > 3) {
+ /* morton gets to eat his hat */
+ printk("%s: recursion depth exceeded: %d\n",
+ __FUNCTION__, cwq->run_depth);
+ dump_stack();
+ }
+ while (!list_empty(&cwq->worklist)) {
+ struct work_struct *work = list_entry(cwq->worklist.next,
+ struct work_struct, entry);
+ void (*f) (void *) = work->func;
+ void *data = work->data;
+
+ list_del_init(cwq->worklist.next);
+ spin_unlock_irqrestore(&cwq->lock, flags);
+
+ BUG_ON(work->wq_data != cwq);
+ clear_bit(0, &work->pending);
+ f(data);
+
+ spin_lock_irqsave(&cwq->lock, flags);
+ cwq->remove_sequence++;
+ wake_up(&cwq->work_done);
+ }
+ cwq->run_depth--;
+ spin_unlock_irqrestore(&cwq->lock, flags);
+}
+
+static int worker_thread(void *__cwq)
+{
+ struct cpu_workqueue_struct *cwq = __cwq;
+ DECLARE_WAITQUEUE(wait, current);
+ struct k_sigaction sa;
+ sigset_t blocked;
+
+ current->flags |= PF_NOFREEZE;
+
+ set_user_nice(current, -5);
+
+ /* Block and flush all signals */
+ sigfillset(&blocked);
+ sigprocmask(SIG_BLOCK, &blocked, NULL);
+ flush_signals(current);
+
+ /* SIG_IGN makes children autoreap: see do_notify_parent(). */
+ sa.sa.sa_handler = SIG_IGN;
+ sa.sa.sa_flags = 0;
+ siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
+ do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ add_wait_queue(&cwq->more_work, &wait);
+ if (list_empty(&cwq->worklist))
+ schedule();
+ else
+ __set_current_state(TASK_RUNNING);
+ remove_wait_queue(&cwq->more_work, &wait);
+
+ if (!list_empty(&cwq->worklist))
+ run_workqueue(cwq);
+ set_current_state(TASK_INTERRUPTIBLE);
+ }
+ __set_current_state(TASK_RUNNING);
+ return 0;
+}
+
+static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
+{
+ if (cwq->thread == current) {
+ /*
+ * Probably keventd trying to flush its own queue. So simply run
+ * it by hand rather than deadlocking.
+ */
+ run_workqueue(cwq);
+ } else {
+ DEFINE_WAIT(wait);
+ long sequence_needed;
+
+ spin_lock_irq(&cwq->lock);
+ sequence_needed = cwq->insert_sequence;
+
+ while (sequence_needed - cwq->remove_sequence > 0) {
+ prepare_to_wait(&cwq->work_done, &wait,
+ TASK_UNINTERRUPTIBLE);
+ spin_unlock_irq(&cwq->lock);
+ schedule();
+ spin_lock_irq(&cwq->lock);
+ }
+ finish_wait(&cwq->work_done, &wait);
+ spin_unlock_irq(&cwq->lock);
+ }
+}
+
+/*
+ * flush_workqueue - ensure that any scheduled work has run to completion.
+ *
+ * Forces execution of the workqueue and blocks until its completion.
+ * This is typically used in driver shutdown handlers.
+ *
+ * This function will sample each workqueue's current insert_sequence number and
+ * will sleep until the head sequence is greater than or equal to that. This
+ * means that we sleep until all works which were queued on entry have been
+ * handled, but we are not livelocked by new incoming ones.
+ *
+ * This function used to run the workqueues itself. Now we just wait for the
+ * helper threads to do it.
+ */
+void fastcall flush_workqueue(struct workqueue_struct *wq)
+{
+ might_sleep();
+
+ if (is_single_threaded(wq)) {
+ /* Always use cpu 0's area. */
+ flush_cpu_workqueue(wq->cpu_wq + 0);
+ } else {
+ int cpu;
+
+ lock_cpu_hotplug();
+ for_each_online_cpu(cpu)
+ flush_cpu_workqueue(wq->cpu_wq + cpu);
+ unlock_cpu_hotplug();
+ }
+}
+
+static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
+ int cpu)
+{
+ struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
+ struct task_struct *p;
+
+ spin_lock_init(&cwq->lock);
+ cwq->wq = wq;
+ cwq->thread = NULL;
+ cwq->insert_sequence = 0;
+ cwq->remove_sequence = 0;
+ INIT_LIST_HEAD(&cwq->worklist);
+ init_waitqueue_head(&cwq->more_work);
+ init_waitqueue_head(&cwq->work_done);
+
+ if (is_single_threaded(wq))
+ p = kthread_create(worker_thread, cwq, "%s", wq->name);
+ else
+ p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu);
+ if (IS_ERR(p))
+ return NULL;
+ cwq->thread = p;
+ return p;
+}
+
+struct workqueue_struct *__create_workqueue(const char *name,
+ int singlethread)
+{
+ int cpu, destroy = 0;
+ struct workqueue_struct *wq;
+ struct task_struct *p;
+
+ BUG_ON(strlen(name) > 10);
+
+ wq = kmalloc(sizeof(*wq), GFP_KERNEL);
+ if (!wq)
+ return NULL;
+ memset(wq, 0, sizeof(*wq));
+
+ wq->name = name;
+ /* We don't need the distraction of CPUs appearing and vanishing. */
+ lock_cpu_hotplug();
+ if (singlethread) {
+ INIT_LIST_HEAD(&wq->list);
+ p = create_workqueue_thread(wq, 0);
+ if (!p)
+ destroy = 1;
+ else
+ wake_up_process(p);
+ } else {
+ spin_lock(&workqueue_lock);
+ list_add(&wq->list, &workqueues);
+ spin_unlock(&workqueue_lock);
+ for_each_online_cpu(cpu) {
+ p = create_workqueue_thread(wq, cpu);
+ if (p) {
+ kthread_bind(p, cpu);
+ wake_up_process(p);
+ } else
+ destroy = 1;
+ }
+ }
+ unlock_cpu_hotplug();
+
+ /*
+ * Was there any error during startup? If yes then clean up:
+ */
+ if (destroy) {
+ destroy_workqueue(wq);
+ wq = NULL;
+ }
+ return wq;
+}
+
+static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
+{
+ struct cpu_workqueue_struct *cwq;
+ unsigned long flags;
+ struct task_struct *p;
+
+ cwq = wq->cpu_wq + cpu;
+ spin_lock_irqsave(&cwq->lock, flags);
+ p = cwq->thread;
+ cwq->thread = NULL;
+ spin_unlock_irqrestore(&cwq->lock, flags);
+ if (p)
+ kthread_stop(p);
+}
+
+void destroy_workqueue(struct workqueue_struct *wq)
+{
+ int cpu;
+
+ flush_workqueue(wq);
+
+ /* We don't need the distraction of CPUs appearing and vanishing. */
+ lock_cpu_hotplug();
+ if (is_single_threaded(wq))
+ cleanup_workqueue_thread(wq, 0);
+ else {
+ for_each_online_cpu(cpu)
+ cleanup_workqueue_thread(wq, cpu);
+ spin_lock(&workqueue_lock);
+ list_del(&wq->list);
+ spin_unlock(&workqueue_lock);
+ }
+ unlock_cpu_hotplug();
+ kfree(wq);
+}
+
+static struct workqueue_struct *keventd_wq;
+
+int fastcall schedule_work(struct work_struct *work)
+{
+ return queue_work(keventd_wq, work);
+}
+
+int fastcall schedule_delayed_work(struct work_struct *work, unsigned long delay)
+{
+ return queue_delayed_work(keventd_wq, work, delay);
+}
+
+int schedule_delayed_work_on(int cpu,
+ struct work_struct *work, unsigned long delay)
+{
+ int ret = 0;
+ struct timer_list *timer = &work->timer;
+
+ if (!test_and_set_bit(0, &work->pending)) {
+ BUG_ON(timer_pending(timer));
+ BUG_ON(!list_empty(&work->entry));
+ /* This stores keventd_wq for the moment, for the timer_fn */
+ work->wq_data = keventd_wq;
+ timer->expires = jiffies + delay;
+ timer->data = (unsigned long)work;
+ timer->function = delayed_work_timer_fn;
+ add_timer_on(timer, cpu);
+ ret = 1;
+ }
+ return ret;
+}
+
+void flush_scheduled_work(void)
+{
+ flush_workqueue(keventd_wq);
+}
+
+/**
+ * cancel_rearming_delayed_workqueue - reliably kill off a delayed
+ * work whose handler rearms the delayed work.
+ * @wq: the controlling workqueue structure
+ * @work: the delayed work struct
+ */
+static void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
+ struct work_struct *work)
+{
+ while (!cancel_delayed_work(work))
+ 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);
generated by cgit v1.1 at 2024-10-31 19:04:40 +0000