/*
- * linux/kernel/workqueue.c
+ * kernel/workqueue.c - generic async execution with shared worker pool
*
- * Generic mechanism for defining kernel helper threads for running
- * arbitrary tasks in process context.
+ * Copyright (C) 2002 Ingo Molnar
*
- * Started by Ingo Molnar, Copyright (C) 2002
+ * Derived from the taskqueue/keventd code by:
+ * David Woodhouse <dwmw2@infradead.org>
+ * Andrew Morton
+ * Kai Petzke <wpp@marie.physik.tu-berlin.de>
+ * Theodore Ts'o <tytso@mit.edu>
*
- * Derived from the taskqueue/keventd code by:
+ * Made to use alloc_percpu by Christoph Lameter.
*
- * David Woodhouse <dwmw2@infradead.org>
- * Andrew Morton
- * Kai Petzke <wpp@marie.physik.tu-berlin.de>
- * Theodore Ts'o <tytso@mit.edu>
+ * Copyright (C) 2010 SUSE Linux Products GmbH
+ * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
*
- * Made to use alloc_percpu by Christoph Lameter.
+ * This is the generic async execution mechanism. Work items as are
+ * executed in process context. The worker pool is shared and
+ * automatically managed. There is one worker pool for each CPU and
+ * one extra for works which are better served by workers which are
+ * not bound to any specific CPU.
+ *
+ * Please read Documentation/workqueue.txt for details.
*/
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
- MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
+ MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
+ /* call for help after 10ms
+ (min two ticks) */
MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
CREATE_COOLDOWN = HZ, /* time to breath after fail */
TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
/*
* Structure fields follow one of the following exclusion rules.
*
- * I: Set during initialization and read-only afterwards.
+ * I: Modifiable by initialization/destruction paths and read-only for
+ * everyone else.
*
* P: Preemption protected. Disabling preemption is enough and should
* only be modified and accessed from the local cpu.
};
/*
+ * All cpumasks are assumed to be always set on UP and thus can't be
+ * used to determine whether there's something to be done.
+ */
+#ifdef CONFIG_SMP
+typedef cpumask_var_t mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask) \
+ cpumask_test_and_set_cpu((cpu), (mask))
+#define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
+#define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
+#define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
+#define free_mayday_mask(mask) free_cpumask_var((mask))
+#else
+typedef unsigned long mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
+#define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
+#define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
+#define alloc_mayday_mask(maskp, gfp) true
+#define free_mayday_mask(mask) do { } while (0)
+#endif
+
+/*
* The externally visible workqueue abstraction is an array of
* per-CPU workqueues:
*/
struct workqueue_struct {
- unsigned int flags; /* I: WQ_* flags */
+ unsigned int flags; /* W: WQ_* flags */
union {
struct cpu_workqueue_struct __percpu *pcpu;
struct cpu_workqueue_struct *single;
struct list_head flusher_queue; /* F: flush waiters */
struct list_head flusher_overflow; /* F: flush overflow list */
- cpumask_var_t mayday_mask; /* cpus requesting rescue */
+ mayday_mask_t mayday_mask; /* cpus requesting rescue */
struct worker *rescuer; /* I: rescue worker */
+ int nr_drainers; /* W: drain in progress */
int saved_max_active; /* W: saved cwq max_active */
- const char *name; /* I: workqueue name */
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
+ char name[]; /* I: workqueue name */
};
struct workqueue_struct *system_wq __read_mostly;
struct workqueue_struct *system_long_wq __read_mostly;
struct workqueue_struct *system_nrt_wq __read_mostly;
struct workqueue_struct *system_unbound_wq __read_mostly;
+struct workqueue_struct *system_freezable_wq __read_mostly;
+struct workqueue_struct *system_nrt_freezable_wq __read_mostly;
EXPORT_SYMBOL_GPL(system_wq);
EXPORT_SYMBOL_GPL(system_long_wq);
EXPORT_SYMBOL_GPL(system_nrt_wq);
EXPORT_SYMBOL_GPL(system_unbound_wq);
+EXPORT_SYMBOL_GPL(system_freezable_wq);
+EXPORT_SYMBOL_GPL(system_nrt_freezable_wq);
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/workqueue.h>
#define for_each_busy_worker(worker, i, pos, gcwq) \
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
}
+/*
+ * CPU iterators
+ *
+ * An extra gcwq is defined for an invalid cpu number
+ * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
+ * specific CPU. The following iterators are similar to
+ * for_each_*_cpu() iterators but also considers the unbound gcwq.
+ *
+ * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
+ * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
+ * for_each_cwq_cpu() : possible CPUs for bound workqueues,
+ * WORK_CPU_UNBOUND for unbound workqueues
+ */
#define for_each_gcwq_cpu(cpu) \
for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
(cpu) < WORK_CPU_NONE; \
static struct debug_obj_descr work_debug_descr;
+static void *work_debug_hint(void *addr)
+{
+ return ((struct work_struct *) addr)->func;
+}
+
/*
* fixup_init is called when:
* - an active object is initialized
static struct debug_obj_descr work_debug_descr = {
.name = "work_struct",
+ .debug_hint = work_debug_hint,
.fixup_init = work_fixup_init,
.fixup_activate = work_fixup_activate,
.fixup_free = work_fixup_free,
struct workqueue_struct *wq)
{
if (!(wq->flags & WQ_UNBOUND)) {
- if (likely(cpu < nr_cpu_ids)) {
-#ifdef CONFIG_SMP
+ if (likely(cpu < nr_cpu_ids))
return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
-#else
- return wq->cpu_wq.single;
-#endif
- }
} else if (likely(cpu == WORK_CPU_UNBOUND))
return wq->cpu_wq.single;
return NULL;
}
/*
- * Work data points to the cwq while a work is on queue. Once
- * execution starts, it points to the cpu the work was last on. This
- * can be distinguished by comparing the data value against
- * PAGE_OFFSET.
+ * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
+ * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
+ * cleared and the work data contains the cpu number it was last on.
*
* set_work_{cwq|cpu}() and clear_work_data() can be used to set the
* cwq, cpu or clear work->data. These functions should only be
unsigned long extra_flags)
{
set_work_data(work, (unsigned long)cwq,
- WORK_STRUCT_PENDING | extra_flags);
+ WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
}
static void set_work_cpu(struct work_struct *work, unsigned int cpu)
set_work_data(work, WORK_STRUCT_NO_CPU, 0);
}
-static inline unsigned long get_work_data(struct work_struct *work)
-{
- return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK;
-}
-
static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
{
- unsigned long data = get_work_data(work);
+ unsigned long data = atomic_long_read(&work->data);
- return data >= PAGE_OFFSET ? (void *)data : NULL;
+ if (data & WORK_STRUCT_CWQ)
+ return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+ else
+ return NULL;
}
static struct global_cwq *get_work_gcwq(struct work_struct *work)
{
- unsigned long data = get_work_data(work);
+ unsigned long data = atomic_long_read(&work->data);
unsigned int cpu;
- if (data >= PAGE_OFFSET)
- return ((struct cpu_workqueue_struct *)data)->gcwq;
+ if (data & WORK_STRUCT_CWQ)
+ return ((struct cpu_workqueue_struct *)
+ (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
cpu = data >> WORK_STRUCT_FLAG_BITS;
if (cpu == WORK_CPU_NONE)
{
atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
- return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
+ return !list_empty(&gcwq->worklist) &&
+ (atomic_read(nr_running) <= 1 ||
+ gcwq->flags & GCWQ_HIGHPRI_PENDING);
}
/* Do we need a new worker? Called from manager. */
{
struct worker *worker = kthread_data(task);
- if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
+ if (!(worker->flags & WORKER_NOT_RUNNING))
atomic_inc(get_gcwq_nr_running(cpu));
}
struct global_cwq *gcwq = get_gcwq(cpu);
atomic_t *nr_running = get_gcwq_nr_running(cpu);
- if (unlikely(worker->flags & WORKER_NOT_RUNNING))
+ if (worker->flags & WORKER_NOT_RUNNING)
return NULL;
/* this can only happen on the local cpu */
worker->flags &= ~flags;
- /* if transitioning out of NOT_RUNNING, increment nr_running */
+ /*
+ * If transitioning out of NOT_RUNNING, increment nr_running. Note
+ * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
+ * of multiple flags, not a single flag.
+ */
if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
if (!(worker->flags & WORKER_NOT_RUNNING))
atomic_inc(get_gcwq_nr_running(gcwq->cpu));
wake_up_worker(gcwq);
}
+/*
+ * Test whether @work is being queued from another work executing on the
+ * same workqueue. This is rather expensive and should only be used from
+ * cold paths.
+ */
+static bool is_chained_work(struct workqueue_struct *wq)
+{
+ unsigned long flags;
+ unsigned int cpu;
+
+ for_each_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct worker *worker;
+ struct hlist_node *pos;
+ int i;
+
+ spin_lock_irqsave(&gcwq->lock, flags);
+ for_each_busy_worker(worker, i, pos, gcwq) {
+ if (worker->task != current)
+ continue;
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+ /*
+ * I'm @worker, no locking necessary. See if @work
+ * is headed to the same workqueue.
+ */
+ return worker->current_cwq->wq == wq;
+ }
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+ }
+ return false;
+}
+
static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
struct work_struct *work)
{
struct global_cwq *gcwq;
struct cpu_workqueue_struct *cwq;
struct list_head *worklist;
+ unsigned int work_flags;
unsigned long flags;
debug_work_activate(work);
+ /* if dying, only works from the same workqueue are allowed */
+ if (unlikely(wq->flags & WQ_DRAINING) &&
+ WARN_ON_ONCE(!is_chained_work(wq)))
+ return;
+
/* determine gcwq to use */
if (!(wq->flags & WQ_UNBOUND)) {
struct global_cwq *last_gcwq;
/* gcwq determined, get cwq and queue */
cwq = get_cwq(gcwq->cpu, wq);
+ trace_workqueue_queue_work(cpu, cwq, work);
BUG_ON(!list_empty(&work->entry));
cwq->nr_in_flight[cwq->work_color]++;
+ work_flags = work_color_to_flags(cwq->work_color);
if (likely(cwq->nr_active < cwq->max_active)) {
+ trace_workqueue_activate_work(work);
cwq->nr_active++;
worklist = gcwq_determine_ins_pos(gcwq, cwq);
- } else
+ } else {
+ work_flags |= WORK_STRUCT_DELAYED;
worklist = &cwq->delayed_works;
+ }
- insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
+ insert_work(cwq, work, worklist, work_flags);
spin_unlock_irqrestore(&gcwq->lock, flags);
}
* bound), %false if offline.
*/
static bool worker_maybe_bind_and_lock(struct worker *worker)
+__acquires(&gcwq->lock)
{
struct global_cwq *gcwq = worker->gcwq;
struct task_struct *task = worker->task;
return true;
spin_unlock_irq(&gcwq->lock);
- /* CPU has come up inbetween, retry migration */
+ /*
+ * We've raced with CPU hot[un]plug. Give it a breather
+ * and retry migration. cond_resched() is required here;
+ * otherwise, we might deadlock against cpu_stop trying to
+ * bring down the CPU on non-preemptive kernel.
+ */
cpu_relax();
+ cond_resched();
}
}
worker->id = id;
if (!on_unbound_cpu)
- worker->task = kthread_create(worker_thread, worker,
- "kworker/%u:%d", gcwq->cpu, id);
+ worker->task = kthread_create_on_node(worker_thread,
+ worker,
+ cpu_to_node(gcwq->cpu),
+ "kworker/%u:%d", gcwq->cpu, id);
else
worker->task = kthread_create(worker_thread, worker,
"kworker/u:%d", id);
/* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
if (cpu == WORK_CPU_UNBOUND)
cpu = 0;
- if (!cpumask_test_and_set_cpu(cpu, wq->mayday_mask))
+ if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
wake_up_process(wq->rescuer->task);
return true;
}
* otherwise.
*/
static bool maybe_create_worker(struct global_cwq *gcwq)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
{
if (!need_to_create_worker(gcwq))
return false;
restart:
+ spin_unlock_irq(&gcwq->lock);
+
/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
while (true) {
struct worker *worker;
- spin_unlock_irq(&gcwq->lock);
-
worker = create_worker(gcwq, true);
if (worker) {
del_timer_sync(&gcwq->mayday_timer);
if (!need_to_create_worker(gcwq))
break;
- spin_unlock_irq(&gcwq->lock);
__set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(CREATE_COOLDOWN);
- spin_lock_irq(&gcwq->lock);
+
if (!need_to_create_worker(gcwq))
break;
}
- spin_unlock_irq(&gcwq->lock);
del_timer_sync(&gcwq->mayday_timer);
spin_lock_irq(&gcwq->lock);
if (need_to_create_worker(gcwq))
struct work_struct, entry);
struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
+ trace_workqueue_activate_work(work);
move_linked_works(work, pos, NULL);
+ __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
cwq->nr_active++;
}
* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
* @cwq: cwq of interest
* @color: color of work which left the queue
+ * @delayed: for a delayed work
*
* A work either has completed or is removed from pending queue,
* decrement nr_in_flight of its cwq and handle workqueue flushing.
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
-static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
+static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
+ bool delayed)
{
/* ignore uncolored works */
if (color == WORK_NO_COLOR)
return;
cwq->nr_in_flight[color]--;
- cwq->nr_active--;
- if (!list_empty(&cwq->delayed_works)) {
- /* one down, submit a delayed one */
- if (cwq->nr_active < cwq->max_active)
- cwq_activate_first_delayed(cwq);
+ if (!delayed) {
+ cwq->nr_active--;
+ if (!list_empty(&cwq->delayed_works)) {
+ /* one down, submit a delayed one */
+ if (cwq->nr_active < cwq->max_active)
+ cwq_activate_first_delayed(cwq);
+ }
}
/* is flush in progress and are we at the flushing tip? */
* spin_lock_irq(gcwq->lock) which is released and regrabbed.
*/
static void process_one_work(struct worker *worker, struct work_struct *work)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
{
struct cpu_workqueue_struct *cwq = get_work_cwq(work);
struct global_cwq *gcwq = cwq->gcwq;
spin_unlock_irq(&gcwq->lock);
work_clear_pending(work);
- lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_acquire_read(&cwq->wq->lockdep_map);
lock_map_acquire(&lockdep_map);
+ trace_workqueue_execute_start(work);
f(work);
+ /*
+ * While we must be careful to not use "work" after this, the trace
+ * point will only record its address.
+ */
+ trace_workqueue_execute_end(work);
lock_map_release(&lockdep_map);
lock_map_release(&cwq->wq->lockdep_map);
hlist_del_init(&worker->hentry);
worker->current_work = NULL;
worker->current_cwq = NULL;
- cwq_dec_nr_in_flight(cwq, work_color);
+ cwq_dec_nr_in_flight(cwq, work_color, false);
}
/**
* See whether any cpu is asking for help. Unbounded
* workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
*/
- for_each_cpu(cpu, wq->mayday_mask) {
+ for_each_mayday_cpu(cpu, wq->mayday_mask) {
unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
struct global_cwq *gcwq = cwq->gcwq;
struct work_struct *work, *n;
__set_current_state(TASK_RUNNING);
- cpumask_clear_cpu(cpu, wq->mayday_mask);
+ mayday_clear_cpu(cpu, wq->mayday_mask);
/* migrate to the target cpu if possible */
rescuer->gcwq = gcwq;
move_linked_works(work, scheduled, &n);
process_scheduled_works(rescuer);
+
+ /*
+ * Leave this gcwq. If keep_working() is %true, notify a
+ * regular worker; otherwise, we end up with 0 concurrency
+ * and stalling the execution.
+ */
+ if (keep_working(gcwq))
+ wake_up_worker(gcwq);
+
spin_unlock_irq(&gcwq->lock);
}
* checks and call back into the fixup functions where we
* might deadlock.
*/
- INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
+ INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
init_completion(&barr->done);
EXPORT_SYMBOL_GPL(flush_workqueue);
/**
- * flush_work - block until a work_struct's callback has terminated
- * @work: the work which is to be flushed
- *
- * Returns false if @work has already terminated.
+ * drain_workqueue - drain a workqueue
+ * @wq: workqueue to drain
*
- * It is expected that, prior to calling flush_work(), the caller has
- * arranged for the work to not be requeued, otherwise it doesn't make
- * sense to use this function.
+ * Wait until the workqueue becomes empty. While draining is in progress,
+ * only chain queueing is allowed. IOW, only currently pending or running
+ * work items on @wq can queue further work items on it. @wq is flushed
+ * repeatedly until it becomes empty. The number of flushing is detemined
+ * by the depth of chaining and should be relatively short. Whine if it
+ * takes too long.
*/
-int flush_work(struct work_struct *work)
+void drain_workqueue(struct workqueue_struct *wq)
+{
+ unsigned int flush_cnt = 0;
+ unsigned int cpu;
+
+ /*
+ * __queue_work() needs to test whether there are drainers, is much
+ * hotter than drain_workqueue() and already looks at @wq->flags.
+ * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
+ */
+ spin_lock(&workqueue_lock);
+ if (!wq->nr_drainers++)
+ wq->flags |= WQ_DRAINING;
+ spin_unlock(&workqueue_lock);
+reflush:
+ flush_workqueue(wq);
+
+ for_each_cwq_cpu(cpu, wq) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ bool drained;
+
+ spin_lock_irq(&cwq->gcwq->lock);
+ drained = !cwq->nr_active && list_empty(&cwq->delayed_works);
+ spin_unlock_irq(&cwq->gcwq->lock);
+
+ if (drained)
+ continue;
+
+ if (++flush_cnt == 10 ||
+ (flush_cnt % 100 == 0 && flush_cnt <= 1000))
+ pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n",
+ wq->name, flush_cnt);
+ goto reflush;
+ }
+
+ spin_lock(&workqueue_lock);
+ if (!--wq->nr_drainers)
+ wq->flags &= ~WQ_DRAINING;
+ spin_unlock(&workqueue_lock);
+}
+EXPORT_SYMBOL_GPL(drain_workqueue);
+
+static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
+ bool wait_executing)
{
struct worker *worker = NULL;
struct global_cwq *gcwq;
struct cpu_workqueue_struct *cwq;
- struct wq_barrier barr;
might_sleep();
gcwq = get_work_gcwq(work);
if (!gcwq)
- return 0;
+ return false;
spin_lock_irq(&gcwq->lock);
if (!list_empty(&work->entry)) {
cwq = get_work_cwq(work);
if (unlikely(!cwq || gcwq != cwq->gcwq))
goto already_gone;
- } else {
+ } else if (wait_executing) {
worker = find_worker_executing_work(gcwq, work);
if (!worker)
goto already_gone;
cwq = worker->current_cwq;
- }
+ } else
+ goto already_gone;
- insert_wq_barrier(cwq, &barr, work, worker);
+ insert_wq_barrier(cwq, barr, work, worker);
spin_unlock_irq(&gcwq->lock);
- lock_map_acquire(&cwq->wq->lockdep_map);
+ /*
+ * If @max_active is 1 or rescuer is in use, flushing another work
+ * item on the same workqueue may lead to deadlock. Make sure the
+ * flusher is not running on the same workqueue by verifying write
+ * access.
+ */
+ if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER)
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ else
+ lock_map_acquire_read(&cwq->wq->lockdep_map);
lock_map_release(&cwq->wq->lockdep_map);
- wait_for_completion(&barr.done);
- destroy_work_on_stack(&barr.work);
- return 1;
+ return true;
already_gone:
spin_unlock_irq(&gcwq->lock);
- return 0;
+ return false;
+}
+
+/**
+ * flush_work - wait for a work to finish executing the last queueing instance
+ * @work: the work to flush
+ *
+ * Wait until @work has finished execution. This function considers
+ * only the last queueing instance of @work. If @work has been
+ * enqueued across different CPUs on a non-reentrant workqueue or on
+ * multiple workqueues, @work might still be executing on return on
+ * some of the CPUs from earlier queueing.
+ *
+ * If @work was queued only on a non-reentrant, ordered or unbound
+ * workqueue, @work is guaranteed to be idle on return if it hasn't
+ * been requeued since flush started.
+ *
+ * RETURNS:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_work(struct work_struct *work)
+{
+ struct wq_barrier barr;
+
+ if (start_flush_work(work, &barr, true)) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return true;
+ } else
+ return false;
}
EXPORT_SYMBOL_GPL(flush_work);
+static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
+{
+ struct wq_barrier barr;
+ struct worker *worker;
+
+ spin_lock_irq(&gcwq->lock);
+
+ worker = find_worker_executing_work(gcwq, work);
+ if (unlikely(worker))
+ insert_wq_barrier(worker->current_cwq, &barr, work, worker);
+
+ spin_unlock_irq(&gcwq->lock);
+
+ if (unlikely(worker)) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return true;
+ } else
+ return false;
+}
+
+static bool wait_on_work(struct work_struct *work)
+{
+ bool ret = false;
+ int cpu;
+
+ might_sleep();
+
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
+
+ for_each_gcwq_cpu(cpu)
+ ret |= wait_on_cpu_work(get_gcwq(cpu), work);
+ return ret;
+}
+
+/**
+ * flush_work_sync - wait until a work has finished execution
+ * @work: the work to flush
+ *
+ * Wait until @work has finished execution. On return, it's
+ * guaranteed that all queueing instances of @work which happened
+ * before this function is called are finished. In other words, if
+ * @work hasn't been requeued since this function was called, @work is
+ * guaranteed to be idle on return.
+ *
+ * RETURNS:
+ * %true if flush_work_sync() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_work_sync(struct work_struct *work)
+{
+ struct wq_barrier barr;
+ bool pending, waited;
+
+ /* we'll wait for executions separately, queue barr only if pending */
+ pending = start_flush_work(work, &barr, false);
+
+ /* wait for executions to finish */
+ waited = wait_on_work(work);
+
+ /* wait for the pending one */
+ if (pending) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ }
+
+ return pending || waited;
+}
+EXPORT_SYMBOL_GPL(flush_work_sync);
+
/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
* so this work can't be re-armed in any way.
debug_work_deactivate(work);
list_del_init(&work->entry);
cwq_dec_nr_in_flight(get_work_cwq(work),
- get_work_color(work));
+ get_work_color(work),
+ *work_data_bits(work) & WORK_STRUCT_DELAYED);
ret = 1;
}
}
return ret;
}
-static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
-{
- struct wq_barrier barr;
- struct worker *worker;
-
- spin_lock_irq(&gcwq->lock);
-
- worker = find_worker_executing_work(gcwq, work);
- if (unlikely(worker))
- insert_wq_barrier(worker->current_cwq, &barr, work, worker);
-
- spin_unlock_irq(&gcwq->lock);
-
- if (unlikely(worker)) {
- wait_for_completion(&barr.done);
- destroy_work_on_stack(&barr.work);
- }
-}
-
-static void wait_on_work(struct work_struct *work)
-{
- int cpu;
-
- might_sleep();
-
- lock_map_acquire(&work->lockdep_map);
- lock_map_release(&work->lockdep_map);
-
- for_each_gcwq_cpu(cpu)
- wait_on_cpu_work(get_gcwq(cpu), work);
-}
-
-static int __cancel_work_timer(struct work_struct *work,
+static bool __cancel_work_timer(struct work_struct *work,
struct timer_list* timer)
{
int ret;
}
/**
- * cancel_work_sync - block until a work_struct's callback has terminated
- * @work: the work which is to be flushed
- *
- * Returns true if @work was pending.
+ * cancel_work_sync - cancel a work and wait for it to finish
+ * @work: the work to cancel
*
- * cancel_work_sync() will cancel the work if it is queued. If the work's
- * callback appears to be running, cancel_work_sync() will block until it
- * has completed.
- *
- * It is possible to use this function if the work re-queues itself. It can
- * cancel the work even if it migrates to another workqueue, however in that
- * case it only guarantees that work->func() has completed on the last queued
- * workqueue.
+ * Cancel @work and wait for its execution to finish. This function
+ * can be used even if the work re-queues itself or migrates to
+ * another workqueue. On return from this function, @work is
+ * guaranteed to be not pending or executing on any CPU.
*
- * 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.
+ * cancel_work_sync(&delayed_work->work) must not be used for
+ * delayed_work's. Use cancel_delayed_work_sync() instead.
*
- * The caller must ensure that workqueue_struct on which this work was last
+ * The caller must ensure that the workqueue on which @work was last
* queued can't be destroyed before this function returns.
+ *
+ * RETURNS:
+ * %true if @work was pending, %false otherwise.
*/
-int cancel_work_sync(struct work_struct *work)
+bool 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
+ * flush_delayed_work - wait for a dwork to finish executing the last queueing
+ * @dwork: the delayed work to flush
+ *
+ * Delayed timer is cancelled and the pending work is queued for
+ * immediate execution. Like flush_work(), this function only
+ * considers the last queueing instance of @dwork.
+ *
+ * RETURNS:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_delayed_work(struct delayed_work *dwork)
+{
+ if (del_timer_sync(&dwork->timer))
+ __queue_work(raw_smp_processor_id(),
+ get_work_cwq(&dwork->work)->wq, &dwork->work);
+ return flush_work(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work);
+
+/**
+ * flush_delayed_work_sync - wait for a dwork to finish
+ * @dwork: the delayed work to flush
+ *
+ * Delayed timer is cancelled and the pending work is queued for
+ * execution immediately. Other than timer handling, its behavior
+ * is identical to flush_work_sync().
+ *
+ * RETURNS:
+ * %true if flush_work_sync() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_delayed_work_sync(struct delayed_work *dwork)
+{
+ if (del_timer_sync(&dwork->timer))
+ __queue_work(raw_smp_processor_id(),
+ get_work_cwq(&dwork->work)->wq, &dwork->work);
+ return flush_work_sync(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work_sync);
+
+/**
+ * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
+ * @dwork: the delayed work cancel
*
- * Returns true if @dwork was pending.
+ * This is cancel_work_sync() for delayed works.
*
- * 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().
+ * RETURNS:
+ * %true if @dwork was pending, %false otherwise.
*/
-int cancel_delayed_work_sync(struct delayed_work *dwork)
+bool cancel_delayed_work_sync(struct delayed_work *dwork)
{
return __cancel_work_timer(&dwork->work, &dwork->timer);
}
EXPORT_SYMBOL(schedule_delayed_work);
/**
- * flush_delayed_work - block until a dwork_struct's callback has terminated
- * @dwork: the delayed work which is to be flushed
- *
- * Any timeout is cancelled, and any pending work is run immediately.
- */
-void flush_delayed_work(struct delayed_work *dwork)
-{
- if (del_timer_sync(&dwork->timer)) {
- __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq,
- &dwork->work);
- put_cpu();
- }
- flush_work(&dwork->work);
-}
-EXPORT_SYMBOL(flush_delayed_work);
-
-/**
* schedule_delayed_work_on - queue work in global workqueue on CPU after delay
* @cpu: cpu to use
* @dwork: job to be done
EXPORT_SYMBOL(schedule_delayed_work_on);
/**
- * schedule_on_each_cpu - call a function on each online CPU from keventd
+ * schedule_on_each_cpu - execute a function synchronously on each online CPU
* @func: the function to call
*
- * Returns zero on success.
- * Returns -ve errno on failure.
- *
+ * schedule_on_each_cpu() executes @func on each online CPU using the
+ * system workqueue and blocks until all CPUs have completed.
* schedule_on_each_cpu() is very slow.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
*/
int schedule_on_each_cpu(work_func_t func)
{
int cpu;
- struct work_struct *works;
+ struct work_struct __percpu *works;
works = alloc_percpu(struct work_struct);
if (!works)
const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
__alignof__(unsigned long long));
- if (CONFIG_SMP && !(wq->flags & WQ_UNBOUND)) {
- /* on SMP, percpu allocator can align itself */
+ if (!(wq->flags & WQ_UNBOUND))
wq->cpu_wq.pcpu = __alloc_percpu(size, align);
- } else {
+ else {
void *ptr;
/*
static void free_cwqs(struct workqueue_struct *wq)
{
- if (CONFIG_SMP && !(wq->flags & WQ_UNBOUND))
+ if (!(wq->flags & WQ_UNBOUND))
free_percpu(wq->cpu_wq.pcpu);
else if (wq->cpu_wq.single) {
/* the pointer to free is stored right after the cwq */
return clamp_val(max_active, 1, lim);
}
-struct workqueue_struct *__alloc_workqueue_key(const char *name,
+struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
unsigned int flags,
int max_active,
struct lock_class_key *key,
- const char *lock_name)
+ const char *lock_name, ...)
{
+ va_list args, args1;
struct workqueue_struct *wq;
unsigned int cpu;
+ size_t namelen;
+
+ /* determine namelen, allocate wq and format name */
+ va_start(args, lock_name);
+ va_copy(args1, args);
+ namelen = vsnprintf(NULL, 0, fmt, args) + 1;
+
+ wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL);
+ if (!wq)
+ goto err;
+
+ vsnprintf(wq->name, namelen, fmt, args1);
+ va_end(args);
+ va_end(args1);
+
+ /*
+ * Workqueues which may be used during memory reclaim should
+ * have a rescuer to guarantee forward progress.
+ */
+ if (flags & WQ_MEM_RECLAIM)
+ flags |= WQ_RESCUER;
/*
* Unbound workqueues aren't concurrency managed and should be
flags |= WQ_HIGHPRI;
max_active = max_active ?: WQ_DFL_ACTIVE;
- max_active = wq_clamp_max_active(max_active, flags, name);
-
- wq = kzalloc(sizeof(*wq), GFP_KERNEL);
- if (!wq)
- goto err;
+ max_active = wq_clamp_max_active(max_active, flags, wq->name);
+ /* init wq */
wq->flags = flags;
wq->saved_max_active = max_active;
mutex_init(&wq->flush_mutex);
INIT_LIST_HEAD(&wq->flusher_queue);
INIT_LIST_HEAD(&wq->flusher_overflow);
- wq->name = name;
lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
INIT_LIST_HEAD(&wq->list);
if (flags & WQ_RESCUER) {
struct worker *rescuer;
- if (!alloc_cpumask_var(&wq->mayday_mask, GFP_KERNEL))
+ if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
goto err;
wq->rescuer = rescuer = alloc_worker();
if (!rescuer)
goto err;
- rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
+ rescuer->task = kthread_create(rescuer_thread, wq, "%s",
+ wq->name);
if (IS_ERR(rescuer->task))
goto err;
- wq->rescuer = rescuer;
rescuer->task->flags |= PF_THREAD_BOUND;
wake_up_process(rescuer->task);
}
*/
spin_lock(&workqueue_lock);
- if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
+ if (workqueue_freezing && wq->flags & WQ_FREEZABLE)
for_each_cwq_cpu(cpu, wq)
get_cwq(cpu, wq)->max_active = 0;
err:
if (wq) {
free_cwqs(wq);
- free_cpumask_var(wq->mayday_mask);
+ free_mayday_mask(wq->mayday_mask);
kfree(wq->rescuer);
kfree(wq);
}
{
unsigned int cpu;
- flush_workqueue(wq);
+ /* drain it before proceeding with destruction */
+ drain_workqueue(wq);
/*
* wq list is used to freeze wq, remove from list after
if (wq->flags & WQ_RESCUER) {
kthread_stop(wq->rescuer->task);
- free_cpumask_var(wq->mayday_mask);
+ free_mayday_mask(wq->mayday_mask);
+ kfree(wq->rescuer);
}
free_cwqs(wq);
spin_lock_irq(&gcwq->lock);
- if (!(wq->flags & WQ_FREEZEABLE) ||
+ if (!(wq->flags & WQ_FREEZABLE) ||
!(gcwq->flags & GCWQ_FREEZING))
get_cwq(gcwq->cpu, wq)->max_active = max_active;
* want to get it over with ASAP - spam rescuers, wake up as
* many idlers as necessary and create new ones till the
* worklist is empty. Note that if the gcwq is frozen, there
- * may be frozen works in freezeable cwqs. Don't declare
+ * may be frozen works in freezable cwqs. Don't declare
* completion while frozen.
*/
while (gcwq->nr_workers != gcwq->nr_idle ||
* multiple times. To be used by cpu_callback.
*/
static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
{
if (!(gcwq->trustee_state == state ||
gcwq->trustee_state == TRUSTEE_DONE)) {
/**
* freeze_workqueues_begin - begin freezing workqueues
*
- * Start freezing workqueues. After this function returns, all
- * freezeable workqueues will queue new works to their frozen_works
- * list instead of gcwq->worklist.
+ * Start freezing workqueues. After this function returns, all freezable
+ * workqueues will queue new works to their frozen_works list instead of
+ * gcwq->worklist.
*
* CONTEXT:
* Grabs and releases workqueue_lock and gcwq->lock's.
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
- if (cwq && wq->flags & WQ_FREEZEABLE)
+ if (cwq && wq->flags & WQ_FREEZABLE)
cwq->max_active = 0;
}
}
/**
- * freeze_workqueues_busy - are freezeable workqueues still busy?
+ * freeze_workqueues_busy - are freezable workqueues still busy?
*
* Check whether freezing is complete. This function must be called
* between freeze_workqueues_begin() and thaw_workqueues().
* Grabs and releases workqueue_lock.
*
* RETURNS:
- * %true if some freezeable workqueues are still busy. %false if
- * freezing is complete.
+ * %true if some freezable workqueues are still busy. %false if freezing
+ * is complete.
*/
bool freeze_workqueues_busy(void)
{
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
- if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+ if (!cwq || !(wq->flags & WQ_FREEZABLE))
continue;
BUG_ON(cwq->nr_active < 0);
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
- if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+ if (!cwq || !(wq->flags & WQ_FREEZABLE))
continue;
/* restore max_active and repopulate worklist */
}
#endif /* CONFIG_FREEZER */
-void __init init_workqueues(void)
+static int __init init_workqueues(void)
{
unsigned int cpu;
int i;
- /*
- * The pointer part of work->data is either pointing to the
- * cwq or contains the cpu number the work ran last on. Make
- * sure cpu number won't overflow into kernel pointer area so
- * that they can be distinguished.
- */
- BUILD_BUG_ON(WORK_CPU_LAST << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET);
-
- hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
+ cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
/* initialize gcwqs */
for_each_gcwq_cpu(cpu) {
spin_lock_init(&gcwq->lock);
INIT_LIST_HEAD(&gcwq->worklist);
gcwq->cpu = cpu;
- if (cpu == WORK_CPU_UNBOUND)
- gcwq->flags |= GCWQ_DISASSOCIATED;
+ gcwq->flags |= GCWQ_DISASSOCIATED;
INIT_LIST_HEAD(&gcwq->idle_list);
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
struct global_cwq *gcwq = get_gcwq(cpu);
struct worker *worker;
+ if (cpu != WORK_CPU_UNBOUND)
+ gcwq->flags &= ~GCWQ_DISASSOCIATED;
worker = create_worker(gcwq, true);
BUG_ON(!worker);
spin_lock_irq(&gcwq->lock);
system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
WQ_UNBOUND_MAX_ACTIVE);
- BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
+ system_freezable_wq = alloc_workqueue("events_freezable",
+ WQ_FREEZABLE, 0);
+ system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable",
+ WQ_NON_REENTRANT | WQ_FREEZABLE, 0);
+ BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq ||
+ !system_unbound_wq || !system_freezable_wq ||
+ !system_nrt_freezable_wq);
+ return 0;
}
+early_initcall(init_workqueues);
projects / linux-flexiantxendom0-3.2.10.git / blobdiff