Linux-2.6.12-rc2v2.6.12-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!

1 files changed, 555 insertions, 0 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
new file mode 100644
index 0000000..52ef419
--- /dev/null
+++ b/kernel/workqueue.c
@@ -0,0 +1,555 @@
+/*
+ * 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);