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 000000000000..52ef419d2747
--- /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);