#include "workqueue_sched.h"
enum {
- /* global_cwq flags */
+ /*
+ * global_cwq flags
+ *
+ * A bound gcwq is either associated or disassociated with its CPU.
+ * While associated (!DISASSOCIATED), all workers are bound to the
+ * CPU and none has %WORKER_UNBOUND set and concurrency management
+ * is in effect.
+ *
+ * While DISASSOCIATED, the cpu may be offline and all workers have
+ * %WORKER_UNBOUND set and concurrency management disabled, and may
+ * 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
+ * state while create_worker() is in progress.
+ */
GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */
GCWQ_FREEZING = 1 << 1, /* freeze in progress */
WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND |
WORKER_CPU_INTENSIVE,
- /* gcwq->trustee_state */
- TRUSTEE_START = 0, /* start */
- TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
- TRUSTEE_BUTCHER = 2, /* butcher workers */
- TRUSTEE_RELEASE = 3, /* release workers */
- TRUSTEE_DONE = 4, /* trustee is done */
-
NR_WORKER_POOLS = 2, /* # worker pools per gcwq */
BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
(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 */
/*
* Rescue workers are used only on emergencies and shared by
struct global_cwq;
struct worker_pool;
+struct idle_rebind;
/*
* The poor guys doing the actual heavy lifting. All on-duty workers
unsigned long last_active; /* L: last active timestamp */
unsigned int flags; /* X: flags */
int id; /* I: worker id */
- struct work_struct rebind_work; /* L: rebind worker to cpu */
+
+ /* for rebinding worker to CPU */
+ struct idle_rebind *idle_rebind; /* L: for idle worker */
+ struct work_struct rebind_work; /* L: for busy worker */
};
struct worker_pool {
struct mutex manager_mutex; /* mutex manager should hold */
struct ida worker_ida; /* L: for worker IDs */
- struct worker *first_idle; /* L: first idle worker */
};
/*
struct worker_pool pools[2]; /* normal and highpri pools */
- struct task_struct *trustee; /* L: for gcwq shutdown */
- unsigned int trustee_state; /* L: trustee state */
- wait_queue_head_t trustee_wait; /* trustee wait */
+ wait_queue_head_t rebind_hold; /* rebind hold wait */
} ____cacheline_aligned_in_smp;
/*
* worklist not empty test sequence is in insert_work().
* Please read comment there.
*
- * NOT_RUNNING is clear. This means that trustee is not in
- * charge and we're running on the local cpu w/ rq lock held
- * and preemption disabled, which in turn means that none else
- * could be manipulating idle_list, so dereferencing idle_list
- * without gcwq lock is safe.
+ * NOT_RUNNING is clear. This means that we're bound to and
+ * running on the local cpu w/ rq lock held and preemption
+ * disabled, which in turn means that none else could be
+ * manipulating idle_list, so dereferencing idle_list without gcwq
+ * lock is safe.
*/
if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist))
to_wakeup = first_worker(pool);
/* idle_list is LIFO */
list_add(&worker->entry, &pool->idle_list);
- if (likely(gcwq->trustee_state != TRUSTEE_DONE)) {
- if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
- mod_timer(&pool->idle_timer,
- jiffies + IDLE_WORKER_TIMEOUT);
- } else
- wake_up_all(&gcwq->trustee_wait);
+ if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
+ mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
/*
- * Sanity check nr_running. Because trustee releases gcwq->lock
- * between setting %WORKER_UNBOUND and zapping nr_running, the
- * warning may trigger spuriously. Check iff trustee is idle.
+ * Sanity check nr_running. Because gcwq_unbind_fn() releases
+ * gcwq->lock between setting %WORKER_UNBOUND and zapping
+ * nr_running, the warning may trigger spuriously. Check iff
+ * unbind is not in progress.
*/
- WARN_ON_ONCE(gcwq->trustee_state == TRUSTEE_DONE &&
+ WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) &&
pool->nr_workers == pool->nr_idle &&
atomic_read(get_pool_nr_running(pool)));
}
}
}
+struct idle_rebind {
+ int cnt; /* # workers to be rebound */
+ struct completion done; /* all workers rebound */
+};
+
/*
- * Function for worker->rebind_work used to rebind unbound busy workers to
+ * 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.
+ */
+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));
+}
+
+/*
+ * Function for @worker->rebind.work used to rebind unbound busy workers to
* the associated cpu which is coming back online. This is scheduled by
* cpu up but can race with other cpu hotplug operations and may be
* executed twice without intervening cpu down.
*/
-static void worker_rebind_fn(struct work_struct *work)
+static void busy_worker_rebind_fn(struct work_struct *work)
{
struct worker *worker = container_of(work, struct worker, rebind_work);
struct global_cwq *gcwq = worker->pool->gcwq;
spin_unlock_irq(&gcwq->lock);
}
+/**
+ * rebind_workers - rebind all workers of a gcwq to the associated CPU
+ * @gcwq: gcwq of interest
+ *
+ * @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.
+ *
+ * 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.
+ *
+ * On return, all workers are guaranteed to either be bound or have rebind
+ * work item scheduled.
+ */
+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 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);
+
+ /* set REBIND and kick idle ones, we'll wait for these later */
+ for_each_worker_pool(pool, gcwq) {
+ list_for_each_entry(worker, &pool->idle_list, entry) {
+ if (worker->flags & WORKER_REBIND)
+ continue;
+
+ /* morph UNBOUND to REBIND */
+ worker->flags &= ~WORKER_UNBOUND;
+ worker->flags |= WORKER_REBIND;
+
+ idle_rebind.cnt++;
+ worker->idle_rebind = &idle_rebind;
+
+ /* worker_thread() will 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 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.
+ */
+ for_each_worker_pool(pool, gcwq)
+ list_for_each_entry(worker, &pool->idle_list, entry)
+ worker->flags &= ~WORKER_REBIND;
+
+ wake_up_all(&gcwq->rebind_hold);
+
+ /* rebind busy workers */
+ for_each_busy_worker(worker, i, pos, gcwq) {
+ struct work_struct *rebind_work = &worker->rebind_work;
+
+ /* morph UNBOUND to REBIND */
+ worker->flags &= ~WORKER_UNBOUND;
+ worker->flags |= WORKER_REBIND;
+
+ if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
+ work_data_bits(rebind_work)))
+ continue;
+
+ /* wq doesn't matter, use the default one */
+ debug_work_activate(rebind_work);
+ insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
+ worker->scheduled.next,
+ work_color_to_flags(WORK_NO_COLOR));
+ }
+}
+
static struct worker *alloc_worker(void)
{
struct worker *worker;
if (worker) {
INIT_LIST_HEAD(&worker->entry);
INIT_LIST_HEAD(&worker->scheduled);
- INIT_WORK(&worker->rebind_work, worker_rebind_fn);
+ INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn);
/* on creation a worker is in !idle && prep state */
worker->flags = WORKER_PREP;
}
/**
* create_worker - create a new workqueue worker
* @pool: pool the new worker will belong to
- * @bind: whether to set affinity to @cpu or not
*
* Create a new worker which is bound to @pool. The returned worker
* can be started by calling start_worker() or destroyed using
* RETURNS:
* Pointer to the newly created worker.
*/
-static struct worker *create_worker(struct worker_pool *pool, bool bind)
+static struct worker *create_worker(struct worker_pool *pool)
{
struct global_cwq *gcwq = pool->gcwq;
- bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
const char *pri = worker_pool_pri(pool) ? "H" : "";
struct worker *worker = NULL;
int id = -1;
worker->pool = pool;
worker->id = id;
- if (!on_unbound_cpu)
+ if (gcwq->cpu != WORK_CPU_UNBOUND)
worker->task = kthread_create_on_node(worker_thread,
worker, cpu_to_node(gcwq->cpu),
"kworker/%u:%d%s", gcwq->cpu, id, pri);
set_user_nice(worker->task, HIGHPRI_NICE_LEVEL);
/*
- * An unbound worker will become a regular one if CPU comes online
- * later on. Make sure every worker has PF_THREAD_BOUND set.
+ * Determine CPU binding of the new worker depending on
+ * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the
+ * flag remains stable across this function. See the comments
+ * above the flag definition for details.
+ *
+ * As an unbound worker may later become a regular one if CPU comes
+ * online, make sure every worker has %PF_THREAD_BOUND set.
*/
- if (bind && !on_unbound_cpu)
+ if (!(gcwq->flags & GCWQ_DISASSOCIATED)) {
kthread_bind(worker->task, gcwq->cpu);
- else {
+ } else {
worker->task->flags |= PF_THREAD_BOUND;
- if (on_unbound_cpu)
- worker->flags |= WORKER_UNBOUND;
+ worker->flags |= WORKER_UNBOUND;
}
return worker;
while (true) {
struct worker *worker;
- worker = create_worker(pool, true);
+ worker = create_worker(pool);
if (worker) {
del_timer_sync(&pool->mayday_timer);
spin_lock_irq(&gcwq->lock);
lockdep_copy_map(&lockdep_map, &work->lockdep_map);
#endif
+ /*
+ * Ensure we're on the correct CPU. DISASSOCIATED test is
+ * necessary to avoid spurious warnings from rescuers servicing the
+ * unbound or a disassociated gcwq.
+ */
+ WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) &&
+ !(gcwq->flags & GCWQ_DISASSOCIATED) &&
+ raw_smp_processor_id() != gcwq->cpu);
+
/*
* A single work shouldn't be executed concurrently by
* multiple workers on a single cpu. Check whether anyone is
woke_up:
spin_lock_irq(&gcwq->lock);
- /* DIE can be set only while we're idle, checking here is enough */
- if (worker->flags & WORKER_DIE) {
+ /*
+ * 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))) {
spin_unlock_irq(&gcwq->lock);
- worker->task->flags &= ~PF_WQ_WORKER;
- return 0;
+
+ if (worker->flags & WORKER_DIE) {
+ worker->task->flags &= ~PF_WQ_WORKER;
+ return 0;
+ }
+
+ idle_worker_rebind(worker);
+ goto woke_up;
}
worker_leave_idle(worker);
* gcwqs serve mix of short, long and very long running works making
* blocked draining impractical.
*
- * This is solved by allowing a gcwq to be detached from CPU, running it
- * with unbound workers and allowing it to be reattached later if the cpu
- * comes back online. A separate thread is created to govern a gcwq in
- * such state and is called the trustee of the gcwq.
- *
- * Trustee states and their descriptions.
- *
- * START Command state used on startup. On CPU_DOWN_PREPARE, a
- * new trustee is started with this state.
- *
- * IN_CHARGE Once started, trustee will enter this state after
- * assuming the manager role and making all existing
- * workers rogue. DOWN_PREPARE waits for trustee to
- * enter this state. After reaching IN_CHARGE, trustee
- * tries to execute the pending worklist until it's empty
- * and the state is set to BUTCHER, or the state is set
- * to RELEASE.
- *
- * BUTCHER Command state which is set by the cpu callback after
- * the cpu has went down. Once this state is set trustee
- * knows that there will be no new works on the worklist
- * and once the worklist is empty it can proceed to
- * killing idle workers.
- *
- * RELEASE Command state which is set by the cpu callback if the
- * cpu down has been canceled or it has come online
- * again. After recognizing this state, trustee stops
- * trying to drain or butcher and clears ROGUE, rebinds
- * all remaining workers back to the cpu and releases
- * manager role.
- *
- * DONE Trustee will enter this state after BUTCHER or RELEASE
- * is complete.
- *
- * trustee CPU draining
- * took over down complete
- * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
- * | | ^
- * | CPU is back online v return workers |
- * ----------------> RELEASE --------------
+ * This is solved by allowing a gcwq to be disassociated from the CPU
+ * running as an unbound one and allowing it to be reattached later if the
+ * cpu comes back online.
*/
/* claim manager positions of all pools */
-static void gcwq_claim_management(struct global_cwq *gcwq)
+static void gcwq_claim_management_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);
+ spin_lock_irq(&gcwq->lock);
}
/* release manager positions */
-static void gcwq_release_management(struct global_cwq *gcwq)
+static void gcwq_release_management_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);
}
-/**
- * trustee_wait_event_timeout - timed event wait for trustee
- * @cond: condition to wait for
- * @timeout: timeout in jiffies
- *
- * wait_event_timeout() for trustee to use. Handles locking and
- * checks for RELEASE request.
- *
- * CONTEXT:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
- * multiple times. To be used by trustee.
- *
- * RETURNS:
- * Positive indicating left time if @cond is satisfied, 0 if timed
- * out, -1 if canceled.
- */
-#define trustee_wait_event_timeout(cond, timeout) ({ \
- long __ret = (timeout); \
- while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
- __ret) { \
- spin_unlock_irq(&gcwq->lock); \
- __wait_event_timeout(gcwq->trustee_wait, (cond) || \
- (gcwq->trustee_state == TRUSTEE_RELEASE), \
- __ret); \
- spin_lock_irq(&gcwq->lock); \
- } \
- gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
-})
-
-/**
- * trustee_wait_event - event wait for trustee
- * @cond: condition to wait for
- *
- * wait_event() for trustee to use. Automatically handles locking and
- * checks for CANCEL request.
- *
- * CONTEXT:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
- * multiple times. To be used by trustee.
- *
- * RETURNS:
- * 0 if @cond is satisfied, -1 if canceled.
- */
-#define trustee_wait_event(cond) ({ \
- long __ret1; \
- __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
- __ret1 < 0 ? -1 : 0; \
-})
-
-static bool gcwq_has_idle_workers(struct global_cwq *gcwq)
-{
- struct worker_pool *pool;
-
- for_each_worker_pool(pool, gcwq)
- if (!list_empty(&pool->idle_list))
- return true;
- return false;
-}
-
-static int __cpuinit trustee_thread(void *__gcwq)
+static void gcwq_unbind_fn(struct work_struct *work)
{
- struct global_cwq *gcwq = __gcwq;
+ struct global_cwq *gcwq = get_gcwq(smp_processor_id());
struct worker_pool *pool;
struct worker *worker;
- struct work_struct *work;
struct hlist_node *pos;
- long rc;
int i;
BUG_ON(gcwq->cpu != smp_processor_id());
- gcwq_claim_management(gcwq);
- spin_lock_irq(&gcwq->lock);
+ gcwq_claim_management_and_lock(gcwq);
/*
* We've claimed all manager positions. Make all workers unbound
gcwq->flags |= GCWQ_DISASSOCIATED;
+ gcwq_release_management_and_unlock(gcwq);
+
/*
* Call schedule() so that we cross rq->lock and thus can guarantee
- * sched callbacks see the unbound flag. This is necessary as
- * scheduler callbacks may be invoked from other cpus.
+ * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
+ * as scheduler callbacks may be invoked from other cpus.
*/
- spin_unlock_irq(&gcwq->lock);
schedule();
- spin_lock_irq(&gcwq->lock);
/*
- * Sched callbacks are disabled now. Zap nr_running. After
- * this, nr_running stays zero and need_more_worker() and
- * keep_working() are always true as long as the worklist is
- * not empty.
+ * Sched callbacks are disabled now. Zap nr_running. After this,
+ * nr_running stays zero and need_more_worker() and keep_working()
+ * are always true as long as the worklist is not empty. @gcwq now
+ * behaves as unbound (in terms of concurrency management) gcwq
+ * which is served by workers tied to the CPU.
+ *
+ * On return from this function, the current worker would trigger
+ * unbound chain execution of pending work items if other workers
+ * didn't already.
*/
for_each_worker_pool(pool, gcwq)
atomic_set(get_pool_nr_running(pool), 0);
-
- spin_unlock_irq(&gcwq->lock);
- for_each_worker_pool(pool, gcwq)
- del_timer_sync(&pool->idle_timer);
- spin_lock_irq(&gcwq->lock);
-
- /*
- * We're now in charge. Notify and proceed to drain. We need
- * to keep the gcwq running during the whole CPU down
- * procedure as other cpu hotunplug callbacks may need to
- * flush currently running tasks.
- */
- gcwq->trustee_state = TRUSTEE_IN_CHARGE;
- wake_up_all(&gcwq->trustee_wait);
-
- /*
- * The original cpu is in the process of dying and may go away
- * anytime now. When that happens, we and all workers would
- * be migrated to other cpus. Try draining any left work. We
- * 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 freezable cwqs. Don't declare
- * completion while frozen.
- */
- while (true) {
- bool busy = false;
-
- for_each_worker_pool(pool, gcwq)
- busy |= pool->nr_workers != pool->nr_idle;
-
- if (!busy && !(gcwq->flags & GCWQ_FREEZING) &&
- gcwq->trustee_state != TRUSTEE_IN_CHARGE)
- break;
-
- for_each_worker_pool(pool, gcwq) {
- int nr_works = 0;
-
- list_for_each_entry(work, &pool->worklist, entry) {
- send_mayday(work);
- nr_works++;
- }
-
- list_for_each_entry(worker, &pool->idle_list, entry) {
- if (!nr_works--)
- break;
- wake_up_process(worker->task);
- }
-
- if (need_to_create_worker(pool)) {
- spin_unlock_irq(&gcwq->lock);
- worker = create_worker(pool, false);
- spin_lock_irq(&gcwq->lock);
- if (worker) {
- worker->flags |= WORKER_UNBOUND;
- start_worker(worker);
- }
- }
- }
-
- /* give a breather */
- if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
- break;
- }
-
- /*
- * Either all works have been scheduled and cpu is down, or
- * cpu down has already been canceled. Wait for and butcher
- * all workers till we're canceled.
- */
- do {
- rc = trustee_wait_event(gcwq_has_idle_workers(gcwq));
-
- i = 0;
- for_each_worker_pool(pool, gcwq) {
- while (!list_empty(&pool->idle_list)) {
- worker = list_first_entry(&pool->idle_list,
- struct worker, entry);
- destroy_worker(worker);
- }
- i |= pool->nr_workers;
- }
- } while (i && rc >= 0);
-
- /*
- * At this point, either draining has completed and no worker
- * is left, or cpu down has been canceled or the cpu is being
- * brought back up. There shouldn't be any idle one left.
- * Tell the remaining busy ones to rebind once it finishes the
- * currently scheduled works by scheduling the rebind_work.
- */
- for_each_worker_pool(pool, gcwq)
- WARN_ON(!list_empty(&pool->idle_list));
-
- for_each_busy_worker(worker, i, pos, gcwq) {
- struct work_struct *rebind_work = &worker->rebind_work;
-
- /*
- * Rebind_work may race with future cpu hotplug
- * operations. Use a separate flag to mark that
- * rebinding is scheduled.
- */
- worker->flags |= WORKER_REBIND;
- worker->flags &= ~WORKER_UNBOUND;
-
- /* queue rebind_work, wq doesn't matter, use the default one */
- if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
- work_data_bits(rebind_work)))
- continue;
-
- debug_work_activate(rebind_work);
- insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
- worker->scheduled.next,
- work_color_to_flags(WORK_NO_COLOR));
- }
-
- gcwq_release_management(gcwq);
-
- /* notify completion */
- gcwq->trustee = NULL;
- gcwq->trustee_state = TRUSTEE_DONE;
- wake_up_all(&gcwq->trustee_wait);
- spin_unlock_irq(&gcwq->lock);
- return 0;
}
-/**
- * wait_trustee_state - wait for trustee to enter the specified state
- * @gcwq: gcwq the trustee of interest belongs to
- * @state: target state to wait for
- *
- * Wait for the trustee to reach @state. DONE is already matched.
- *
- * CONTEXT:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
- * multiple times. To be used by cpu_callback.
+/*
+ * Workqueues should be brought up before normal priority CPU notifiers.
+ * This will be registered high priority CPU notifier.
*/
-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)) {
- spin_unlock_irq(&gcwq->lock);
- __wait_event(gcwq->trustee_wait,
- gcwq->trustee_state == state ||
- gcwq->trustee_state == TRUSTEE_DONE);
- spin_lock_irq(&gcwq->lock);
- }
-}
-
-static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
- unsigned long action,
- void *hcpu)
+static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb,
+ unsigned long action,
+ void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
struct global_cwq *gcwq = get_gcwq(cpu);
- struct task_struct *new_trustee = NULL;
- struct worker *new_workers[NR_WORKER_POOLS] = { };
struct worker_pool *pool;
- unsigned long flags;
- int i;
- action &= ~CPU_TASKS_FROZEN;
-
- switch (action) {
- case CPU_DOWN_PREPARE:
- new_trustee = kthread_create(trustee_thread, gcwq,
- "workqueue_trustee/%d\n", cpu);
- if (IS_ERR(new_trustee))
- return notifier_from_errno(PTR_ERR(new_trustee));
- kthread_bind(new_trustee, cpu);
- /* fall through */
+ switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
- i = 0;
for_each_worker_pool(pool, gcwq) {
- BUG_ON(pool->first_idle);
- new_workers[i] = create_worker(pool, false);
- if (!new_workers[i++])
- goto err_destroy;
- }
- }
+ struct worker *worker;
- /* some are called w/ irq disabled, don't disturb irq status */
- spin_lock_irqsave(&gcwq->lock, flags);
+ if (pool->nr_workers)
+ continue;
- switch (action) {
- case CPU_DOWN_PREPARE:
- /* initialize trustee and tell it to acquire the gcwq */
- BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
- gcwq->trustee = new_trustee;
- gcwq->trustee_state = TRUSTEE_START;
- wake_up_process(gcwq->trustee);
- wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
- /* fall through */
- case CPU_UP_PREPARE:
- i = 0;
- for_each_worker_pool(pool, gcwq) {
- BUG_ON(pool->first_idle);
- pool->first_idle = new_workers[i++];
- }
- break;
+ worker = create_worker(pool);
+ if (!worker)
+ return NOTIFY_BAD;
- case CPU_POST_DEAD:
- gcwq->trustee_state = TRUSTEE_BUTCHER;
- /* fall through */
- case CPU_UP_CANCELED:
- for_each_worker_pool(pool, gcwq) {
- destroy_worker(pool->first_idle);
- pool->first_idle = NULL;
+ spin_lock_irq(&gcwq->lock);
+ start_worker(worker);
+ spin_unlock_irq(&gcwq->lock);
}
break;
case CPU_DOWN_FAILED:
case CPU_ONLINE:
+ gcwq_claim_management_and_lock(gcwq);
gcwq->flags &= ~GCWQ_DISASSOCIATED;
- if (gcwq->trustee_state != TRUSTEE_DONE) {
- gcwq->trustee_state = TRUSTEE_RELEASE;
- wake_up_process(gcwq->trustee);
- wait_trustee_state(gcwq, TRUSTEE_DONE);
- }
-
- /*
- * Trustee is done and there might be no worker left.
- * Put the first_idle in and request a real manager to
- * take a look.
- */
- for_each_worker_pool(pool, gcwq) {
- spin_unlock_irq(&gcwq->lock);
- kthread_bind(pool->first_idle->task, cpu);
- spin_lock_irq(&gcwq->lock);
- pool->flags |= POOL_MANAGE_WORKERS;
- start_worker(pool->first_idle);
- pool->first_idle = NULL;
- }
+ rebind_workers(gcwq);
+ gcwq_release_management_and_unlock(gcwq);
break;
}
-
- spin_unlock_irqrestore(&gcwq->lock, flags);
-
- return notifier_from_errno(0);
-
-err_destroy:
- if (new_trustee)
- kthread_stop(new_trustee);
-
- spin_lock_irqsave(&gcwq->lock, flags);
- for (i = 0; i < NR_WORKER_POOLS; i++)
- if (new_workers[i])
- destroy_worker(new_workers[i]);
- spin_unlock_irqrestore(&gcwq->lock, flags);
-
- return NOTIFY_BAD;
-}
-
-/*
- * 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,
- unsigned long action,
- void *hcpu)
-{
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_UP_PREPARE:
- case CPU_UP_CANCELED:
- case CPU_DOWN_FAILED:
- case CPU_ONLINE:
- return workqueue_cpu_callback(nfb, action, hcpu);
- }
return NOTIFY_OK;
}
unsigned long action,
void *hcpu)
{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct work_struct unbind_work;
+
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
- case CPU_POST_DEAD:
- return workqueue_cpu_callback(nfb, action, hcpu);
+ /* unbinding should happen on the local CPU */
+ INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn);
+ schedule_work_on(cpu, &unbind_work);
+ flush_work(&unbind_work);
+ break;
}
return NOTIFY_OK;
}
ida_init(&pool->worker_ida);
}
- gcwq->trustee_state = TRUSTEE_DONE;
- init_waitqueue_head(&gcwq->trustee_wait);
+ init_waitqueue_head(&gcwq->rebind_hold);
}
/* create the initial worker */
for_each_worker_pool(pool, gcwq) {
struct worker *worker;
- worker = create_worker(pool, true);
+ worker = create_worker(pool);
BUG_ON(!worker);
spin_lock_irq(&gcwq->lock);
start_worker(worker);
projects / linux-block.git / blobdiff