* be executing on any CPU. The gcwq behaves as an unbound one.
*
* Note that DISASSOCIATED can be flipped only while holding
- * managership of all pools on the gcwq to avoid changing binding
+ * assoc_mutex of all pools on the gcwq to avoid changing binding
* state while create_worker() is in progress.
*/
GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */
WORKER_DIE = 1 << 1, /* die die die */
WORKER_IDLE = 1 << 2, /* is idle */
WORKER_PREP = 1 << 3, /* preparing to run works */
- WORKER_REBIND = 1 << 5, /* mom is home, come back */
WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
WORKER_UNBOUND = 1 << 7, /* worker is unbound */
- WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND |
+ WORKER_NOT_RUNNING = WORKER_PREP | WORKER_UNBOUND |
WORKER_CPU_INTENSIVE,
NR_WORKER_POOLS = 2, /* # worker pools per gcwq */
struct global_cwq;
struct worker_pool;
-struct idle_rebind;
/*
* The poor guys doing the actual heavy lifting. All on-duty workers
int id; /* I: worker id */
/* for rebinding worker to CPU */
- struct idle_rebind *idle_rebind; /* L: for idle worker */
struct work_struct rebind_work; /* L: for busy worker */
};
struct list_head worklist; /* L: list of pending works */
int nr_workers; /* L: total number of workers */
+
+ /* nr_idle includes the ones off idle_list for rebinding */
int nr_idle; /* L: currently idle ones */
struct list_head idle_list; /* X: list of idle workers */
struct timer_list idle_timer; /* L: worker idle timeout */
struct timer_list mayday_timer; /* L: SOS timer for workers */
- struct mutex manager_mutex; /* mutex manager should hold */
+ struct mutex assoc_mutex; /* protect GCWQ_DISASSOCIATED */
struct ida worker_ida; /* L: for worker IDs */
};
struct worker_pool pools[NR_WORKER_POOLS];
/* normal and highpri pools */
-
- wait_queue_head_t rebind_hold; /* rebind hold wait */
} ____cacheline_aligned_in_smp;
/*
int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
int nr_busy = pool->nr_workers - nr_idle;
+ /*
+ * nr_idle and idle_list may disagree if idle rebinding is in
+ * progress. Never return %true if idle_list is empty.
+ */
+ if (list_empty(&pool->idle_list))
+ return false;
+
return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
}
}
}
-struct idle_rebind {
- int cnt; /* # workers to be rebound */
- struct completion done; /* all workers rebound */
-};
-
/*
- * Rebind an idle @worker to its CPU. During CPU onlining, this has to
- * happen synchronously for idle workers. worker_thread() will test
- * %WORKER_REBIND before leaving idle and call this function.
+ * Rebind an idle @worker to its CPU. worker_thread() will test
+ * list_empty(@worker->entry) before leaving idle and call this function.
*/
static void idle_worker_rebind(struct worker *worker)
{
struct global_cwq *gcwq = worker->pool->gcwq;
- /* CPU must be online at this point */
- WARN_ON(!worker_maybe_bind_and_lock(worker));
- if (!--worker->idle_rebind->cnt)
- complete(&worker->idle_rebind->done);
- spin_unlock_irq(&worker->pool->gcwq->lock);
-
- /* we did our part, wait for rebind_workers() to finish up */
- wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));
+ /* CPU may go down again inbetween, clear UNBOUND only on success */
+ if (worker_maybe_bind_and_lock(worker))
+ worker_clr_flags(worker, WORKER_UNBOUND);
- /*
- * rebind_workers() shouldn't finish until all workers passed the
- * above WORKER_REBIND wait. Tell it when done.
- */
- spin_lock_irq(&worker->pool->gcwq->lock);
- if (!--worker->idle_rebind->cnt)
- complete(&worker->idle_rebind->done);
- spin_unlock_irq(&worker->pool->gcwq->lock);
+ /* rebind complete, become available again */
+ list_add(&worker->entry, &worker->pool->idle_list);
+ spin_unlock_irq(&gcwq->lock);
}
/*
struct worker *worker = container_of(work, struct worker, rebind_work);
struct global_cwq *gcwq = worker->pool->gcwq;
- worker_maybe_bind_and_lock(worker);
-
- /*
- * %WORKER_REBIND must be cleared even if the above binding failed;
- * otherwise, we may confuse the next CPU_UP cycle or oops / get
- * stuck by calling idle_worker_rebind() prematurely. If CPU went
- * down again inbetween, %WORKER_UNBOUND would be set, so clearing
- * %WORKER_REBIND is always safe.
- */
- worker_clr_flags(worker, WORKER_REBIND);
+ if (worker_maybe_bind_and_lock(worker))
+ worker_clr_flags(worker, WORKER_UNBOUND);
spin_unlock_irq(&gcwq->lock);
}
* @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding
* is different for idle and busy ones.
*
- * The idle ones should be rebound synchronously and idle rebinding should
- * be complete before any worker starts executing work items with
- * concurrency management enabled; otherwise, scheduler may oops trying to
- * wake up non-local idle worker from wq_worker_sleeping().
- *
- * This is achieved by repeatedly requesting rebinding until all idle
- * workers are known to have been rebound under @gcwq->lock and holding all
- * idle workers from becoming busy until idle rebinding is complete.
+ * Idle ones will be removed from the idle_list and woken up. They will
+ * add themselves back after completing rebind. This ensures that the
+ * idle_list doesn't contain any unbound workers when re-bound busy workers
+ * try to perform local wake-ups for concurrency management.
*
- * Once idle workers are rebound, busy workers can be rebound as they
- * finish executing their current work items. Queueing the rebind work at
- * the head of their scheduled lists is enough. Note that nr_running will
- * be properbly bumped as busy workers rebind.
+ * Busy workers can rebind after they finish their current work items.
+ * Queueing the rebind work item at the head of the scheduled list is
+ * enough. Note that nr_running will be properly bumped as busy workers
+ * rebind.
*
- * On return, all workers are guaranteed to either be bound or have rebind
- * work item scheduled.
+ * On return, all non-manager workers are scheduled for rebind - see
+ * manage_workers() for the manager special case. Any idle worker
+ * including the manager will not appear on @idle_list until rebind is
+ * complete, making local wake-ups safe.
*/
static void rebind_workers(struct global_cwq *gcwq)
- __releases(&gcwq->lock) __acquires(&gcwq->lock)
{
- struct idle_rebind idle_rebind;
struct worker_pool *pool;
- struct worker *worker;
+ struct worker *worker, *n;
struct hlist_node *pos;
int i;
lockdep_assert_held(&gcwq->lock);
for_each_worker_pool(pool, gcwq)
- lockdep_assert_held(&pool->manager_mutex);
-
- /*
- * Rebind idle workers. Interlocked both ways. We wait for
- * workers to rebind via @idle_rebind.done. Workers will wait for
- * us to finish up by watching %WORKER_REBIND.
- */
- init_completion(&idle_rebind.done);
-retry:
- idle_rebind.cnt = 1;
- INIT_COMPLETION(idle_rebind.done);
+ lockdep_assert_held(&pool->assoc_mutex);
- /* set REBIND and kick idle ones, we'll wait for these later */
+ /* dequeue and kick idle ones */
for_each_worker_pool(pool, gcwq) {
- list_for_each_entry(worker, &pool->idle_list, entry) {
- unsigned long worker_flags = worker->flags;
-
- if (worker->flags & WORKER_REBIND)
- continue;
-
- /* morph UNBOUND to REBIND atomically */
- worker_flags &= ~WORKER_UNBOUND;
- worker_flags |= WORKER_REBIND;
- ACCESS_ONCE(worker->flags) = worker_flags;
-
- idle_rebind.cnt++;
- worker->idle_rebind = &idle_rebind;
+ list_for_each_entry_safe(worker, n, &pool->idle_list, entry) {
+ /*
+ * idle workers should be off @pool->idle_list
+ * until rebind is complete to avoid receiving
+ * premature local wake-ups.
+ */
+ list_del_init(&worker->entry);
- /* worker_thread() will call idle_worker_rebind() */
+ /*
+ * worker_thread() will see the above dequeuing
+ * and call idle_worker_rebind().
+ */
wake_up_process(worker->task);
}
}
- if (--idle_rebind.cnt) {
- spin_unlock_irq(&gcwq->lock);
- wait_for_completion(&idle_rebind.done);
- spin_lock_irq(&gcwq->lock);
- /* busy ones might have become idle while waiting, retry */
- goto retry;
- }
-
- /* all idle workers are rebound, rebind busy workers */
+ /* rebind busy workers */
for_each_busy_worker(worker, i, pos, gcwq) {
- unsigned long worker_flags = worker->flags;
struct work_struct *rebind_work = &worker->rebind_work;
struct workqueue_struct *wq;
- /* morph UNBOUND to REBIND atomically */
- worker_flags &= ~WORKER_UNBOUND;
- worker_flags |= WORKER_REBIND;
- ACCESS_ONCE(worker->flags) = worker_flags;
-
if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
work_data_bits(rebind_work)))
continue;
worker->scheduled.next,
work_color_to_flags(WORK_NO_COLOR));
}
-
- /*
- * All idle workers are rebound and waiting for %WORKER_REBIND to
- * be cleared inside idle_worker_rebind(). Clear and release.
- * Clearing %WORKER_REBIND from this foreign context is safe
- * because these workers are still guaranteed to be idle.
- *
- * We need to make sure all idle workers passed WORKER_REBIND wait
- * in idle_worker_rebind() before returning; otherwise, workers can
- * get stuck at the wait if hotplug cycle repeats.
- */
- idle_rebind.cnt = 1;
- INIT_COMPLETION(idle_rebind.done);
-
- for_each_worker_pool(pool, gcwq) {
- list_for_each_entry(worker, &pool->idle_list, entry) {
- worker->flags &= ~WORKER_REBIND;
- idle_rebind.cnt++;
- }
- }
-
- wake_up_all(&gcwq->rebind_hold);
-
- if (--idle_rebind.cnt) {
- spin_unlock_irq(&gcwq->lock);
- wait_for_completion(&idle_rebind.done);
- spin_lock_irq(&gcwq->lock);
- }
}
static struct worker *alloc_worker(void)
* grab %POOL_MANAGING_WORKERS to achieve this because that can
* lead to idle worker depletion (all become busy thinking someone
* else is managing) which in turn can result in deadlock under
- * extreme circumstances. Use @pool->manager_mutex to synchronize
+ * extreme circumstances. Use @pool->assoc_mutex to synchronize
* manager against CPU hotplug.
*
- * manager_mutex would always be free unless CPU hotplug is in
+ * assoc_mutex would always be free unless CPU hotplug is in
* progress. trylock first without dropping @gcwq->lock.
*/
- if (unlikely(!mutex_trylock(&pool->manager_mutex))) {
+ if (unlikely(!mutex_trylock(&pool->assoc_mutex))) {
spin_unlock_irq(&pool->gcwq->lock);
- mutex_lock(&pool->manager_mutex);
+ mutex_lock(&pool->assoc_mutex);
/*
* CPU hotplug could have happened while we were waiting
- * for manager_mutex. Hotplug itself can't handle us
+ * for assoc_mutex. Hotplug itself can't handle us
* because manager isn't either on idle or busy list, and
* @gcwq's state and ours could have deviated.
*
- * As hotplug is now excluded via manager_mutex, we can
+ * As hotplug is now excluded via assoc_mutex, we can
* simply try to bind. It will succeed or fail depending
* on @gcwq's current state. Try it and adjust
* %WORKER_UNBOUND accordingly.
ret |= maybe_create_worker(pool);
pool->flags &= ~POOL_MANAGING_WORKERS;
- mutex_unlock(&pool->manager_mutex);
+ mutex_unlock(&pool->assoc_mutex);
return ret;
}
* necessary to avoid spurious warnings from rescuers servicing the
* unbound or a disassociated gcwq.
*/
- WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) &&
+ WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) &&
!(gcwq->flags & GCWQ_DISASSOCIATED) &&
raw_smp_processor_id() != gcwq->cpu);
woke_up:
spin_lock_irq(&gcwq->lock);
- /*
- * DIE can be set only while idle and REBIND set while busy has
- * @worker->rebind_work scheduled. Checking here is enough.
- */
- if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) {
+ /* we are off idle list if destruction or rebind is requested */
+ if (unlikely(list_empty(&worker->entry))) {
spin_unlock_irq(&gcwq->lock);
+ /* if DIE is set, destruction is requested */
if (worker->flags & WORKER_DIE) {
worker->task->flags &= ~PF_WQ_WORKER;
return 0;
}
+ /* otherwise, rebind */
idle_worker_rebind(worker);
goto woke_up;
}
*/
/* claim manager positions of all pools */
-static void gcwq_claim_management_and_lock(struct global_cwq *gcwq)
+static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq)
{
struct worker_pool *pool;
for_each_worker_pool(pool, gcwq)
- mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools);
+ mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools);
spin_lock_irq(&gcwq->lock);
}
/* release manager positions */
-static void gcwq_release_management_and_unlock(struct global_cwq *gcwq)
+static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq)
{
struct worker_pool *pool;
spin_unlock_irq(&gcwq->lock);
for_each_worker_pool(pool, gcwq)
- mutex_unlock(&pool->manager_mutex);
+ mutex_unlock(&pool->assoc_mutex);
}
static void gcwq_unbind_fn(struct work_struct *work)
BUG_ON(gcwq->cpu != smp_processor_id());
- gcwq_claim_management_and_lock(gcwq);
+ gcwq_claim_assoc_and_lock(gcwq);
/*
* We've claimed all manager positions. Make all workers unbound
gcwq->flags |= GCWQ_DISASSOCIATED;
- gcwq_release_management_and_unlock(gcwq);
+ gcwq_release_assoc_and_unlock(gcwq);
/*
* Call schedule() so that we cross rq->lock and thus can guarantee
* Workqueues should be brought up before normal priority CPU notifiers.
* This will be registered high priority CPU notifier.
*/
-static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb,
+static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
case CPU_DOWN_FAILED:
case CPU_ONLINE:
- gcwq_claim_management_and_lock(gcwq);
+ gcwq_claim_assoc_and_lock(gcwq);
gcwq->flags &= ~GCWQ_DISASSOCIATED;
rebind_workers(gcwq);
- gcwq_release_management_and_unlock(gcwq);
+ gcwq_release_assoc_and_unlock(gcwq);
break;
}
return NOTIFY_OK;
* Workqueues should be brought down after normal priority CPU notifiers.
* This will be registered as low priority CPU notifier.
*/
-static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb,
+static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,
(unsigned long)pool);
- mutex_init(&pool->manager_mutex);
+ mutex_init(&pool->assoc_mutex);
ida_init(&pool->worker_ida);
}
-
- init_waitqueue_head(&gcwq->rebind_hold);
}
/* create the initial worker */
projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blobdiff