diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 1616 |
1 files changed, 900 insertions, 716 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 800b4208dba9..c85825e17df8 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -122,11 +122,6 @@ enum { * * L: pool->lock protected. Access with pool->lock held. * - * X: During normal operation, modification requires pool->lock and should - * be done only from local cpu. Either disabling preemption on local - * cpu or grabbing pool->lock is enough for read access. If - * POOL_DISASSOCIATED is set, it's identical to L. - * * K: Only modified by worker while holding pool->lock. Can be safely read by * self, while holding pool->lock or from IRQ context if %current is the * kworker. @@ -160,7 +155,7 @@ struct worker_pool { int cpu; /* I: the associated cpu */ int node; /* I: the associated node ID */ int id; /* I: pool ID */ - unsigned int flags; /* X: flags */ + unsigned int flags; /* L: flags */ unsigned long watchdog_ts; /* L: watchdog timestamp */ bool cpu_stall; /* WD: stalled cpu bound pool */ @@ -216,6 +211,7 @@ enum pool_workqueue_stats { PWQ_STAT_CPU_TIME, /* total CPU time consumed */ PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */ PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */ + PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */ PWQ_STAT_MAYDAY, /* maydays to rescuer */ PWQ_STAT_RESCUED, /* linked work items executed by rescuer */ @@ -262,12 +258,12 @@ struct pool_workqueue { u64 stats[PWQ_NR_STATS]; /* - * Release of unbound pwq is punted to system_wq. See put_pwq() - * and pwq_unbound_release_workfn() for details. pool_workqueue - * itself is also RCU protected so that the first pwq can be - * determined without grabbing wq->mutex. + * Release of unbound pwq is punted to a kthread_worker. See put_pwq() + * and pwq_release_workfn() for details. pool_workqueue itself is also + * RCU protected so that the first pwq can be determined without + * grabbing wq->mutex. */ - struct work_struct unbound_release_work; + struct kthread_work release_work; struct rcu_head rcu; } __aligned(1 << WORK_STRUCT_FLAG_BITS); @@ -326,14 +322,33 @@ struct workqueue_struct { /* hot fields used during command issue, aligned to cacheline */ unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ - struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ - struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ + struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */ }; static struct kmem_cache *pwq_cache; -static cpumask_var_t *wq_numa_possible_cpumask; - /* possible CPUs of each node */ +/* + * Each pod type describes how CPUs should be grouped for unbound workqueues. + * See the comment above workqueue_attrs->affn_scope. + */ +struct wq_pod_type { + int nr_pods; /* number of pods */ + cpumask_var_t *pod_cpus; /* pod -> cpus */ + int *pod_node; /* pod -> node */ + int *cpu_pod; /* cpu -> pod */ +}; + +static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES]; +static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE; + +static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = { + [WQ_AFFN_DFL] = "default", + [WQ_AFFN_CPU] = "cpu", + [WQ_AFFN_SMT] = "smt", + [WQ_AFFN_CACHE] = "cache", + [WQ_AFFN_NUMA] = "numa", + [WQ_AFFN_SYSTEM] = "system", +}; /* * Per-cpu work items which run for longer than the following threshold are @@ -345,19 +360,14 @@ static cpumask_var_t *wq_numa_possible_cpumask; static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); -static bool wq_disable_numa; -module_param_named(disable_numa, wq_disable_numa, bool, 0444); - /* see the comment above the definition of WQ_POWER_EFFICIENT */ static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); module_param_named(power_efficient, wq_power_efficient, bool, 0444); static bool wq_online; /* can kworkers be created yet? */ -static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ - -/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ -static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; +/* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */ +static struct workqueue_attrs *wq_update_pod_attrs_buf; static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ @@ -371,6 +381,9 @@ static bool workqueue_freezing; /* PL: have wqs started freezing? */ /* PL&A: allowable cpus for unbound wqs and work items */ static cpumask_var_t wq_unbound_cpumask; +/* for further constrain wq_unbound_cpumask by cmdline parameter*/ +static struct cpumask wq_cmdline_cpumask __initdata; + /* CPU where unbound work was last round robin scheduled from this CPU */ static DEFINE_PER_CPU(int, wq_rr_cpu_last); @@ -400,6 +413,13 @@ static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; /* I: attributes used when instantiating ordered pools on demand */ static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; +/* + * I: kthread_worker to release pwq's. pwq release needs to be bounced to a + * process context while holding a pool lock. Bounce to a dedicated kthread + * worker to avoid A-A deadlocks. + */ +static struct kthread_worker *pwq_release_worker; + struct workqueue_struct *system_wq __read_mostly; EXPORT_SYMBOL(system_wq); struct workqueue_struct *system_highpri_wq __read_mostly; @@ -606,35 +626,6 @@ static int worker_pool_assign_id(struct worker_pool *pool) return ret; } -/** - * unbound_pwq_by_node - return the unbound pool_workqueue for the given node - * @wq: the target workqueue - * @node: the node ID - * - * This must be called with any of wq_pool_mutex, wq->mutex or RCU - * read locked. - * If the pwq needs to be used beyond the locking in effect, the caller is - * responsible for guaranteeing that the pwq stays online. - * - * Return: The unbound pool_workqueue for @node. - */ -static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, - int node) -{ - assert_rcu_or_wq_mutex_or_pool_mutex(wq); - - /* - * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a - * delayed item is pending. The plan is to keep CPU -> NODE - * mapping valid and stable across CPU on/offlines. Once that - * happens, this workaround can be removed. - */ - if (unlikely(node == NUMA_NO_NODE)) - return wq->dfl_pwq; - - return rcu_dereference_raw(wq->numa_pwq_tbl[node]); -} - static unsigned int work_color_to_flags(int color) { return color << WORK_STRUCT_COLOR_SHIFT; @@ -825,11 +816,6 @@ static bool work_is_canceling(struct work_struct *work) * they're being called with pool->lock held. */ -static bool __need_more_worker(struct worker_pool *pool) -{ - return !pool->nr_running; -} - /* * Need to wake up a worker? Called from anything but currently * running workers. @@ -840,7 +826,7 @@ static bool __need_more_worker(struct worker_pool *pool) */ static bool need_more_worker(struct worker_pool *pool) { - return !list_empty(&pool->worklist) && __need_more_worker(pool); + return !list_empty(&pool->worklist) && !pool->nr_running; } /* Can I start working? Called from busy but !running workers. */ @@ -871,51 +857,18 @@ static bool too_many_workers(struct worker_pool *pool) return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; } -/* - * Wake up functions. - */ - -/* Return the first idle worker. Called with pool->lock held. */ -static struct worker *first_idle_worker(struct worker_pool *pool) -{ - if (unlikely(list_empty(&pool->idle_list))) - return NULL; - - return list_first_entry(&pool->idle_list, struct worker, entry); -} - -/** - * wake_up_worker - wake up an idle worker - * @pool: worker pool to wake worker from - * - * Wake up the first idle worker of @pool. - * - * CONTEXT: - * raw_spin_lock_irq(pool->lock). - */ -static void wake_up_worker(struct worker_pool *pool) -{ - struct worker *worker = first_idle_worker(pool); - - if (likely(worker)) - wake_up_process(worker->task); -} - /** * worker_set_flags - set worker flags and adjust nr_running accordingly * @worker: self * @flags: flags to set * * Set @flags in @worker->flags and adjust nr_running accordingly. - * - * CONTEXT: - * raw_spin_lock_irq(pool->lock) */ static inline void worker_set_flags(struct worker *worker, unsigned int flags) { struct worker_pool *pool = worker->pool; - WARN_ON_ONCE(worker->task != current); + lockdep_assert_held(&pool->lock); /* If transitioning into NOT_RUNNING, adjust nr_running. */ if ((flags & WORKER_NOT_RUNNING) && @@ -932,16 +885,13 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags) * @flags: flags to clear * * Clear @flags in @worker->flags and adjust nr_running accordingly. - * - * CONTEXT: - * raw_spin_lock_irq(pool->lock) */ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) { struct worker_pool *pool = worker->pool; unsigned int oflags = worker->flags; - WARN_ON_ONCE(worker->task != current); + lockdep_assert_held(&pool->lock); worker->flags &= ~flags; @@ -955,6 +905,244 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) pool->nr_running++; } +/* Return the first idle worker. Called with pool->lock held. */ +static struct worker *first_idle_worker(struct worker_pool *pool) +{ + if (unlikely(list_empty(&pool->idle_list))) + return NULL; + + return list_first_entry(&pool->idle_list, struct worker, entry); +} + +/** + * worker_enter_idle - enter idle state + * @worker: worker which is entering idle state + * + * @worker is entering idle state. Update stats and idle timer if + * necessary. + * + * LOCKING: + * raw_spin_lock_irq(pool->lock). + */ +static void worker_enter_idle(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + + if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || + WARN_ON_ONCE(!list_empty(&worker->entry) && + (worker->hentry.next || worker->hentry.pprev))) + return; + + /* can't use worker_set_flags(), also called from create_worker() */ + worker->flags |= WORKER_IDLE; + pool->nr_idle++; + worker->last_active = jiffies; + + /* idle_list is LIFO */ + list_add(&worker->entry, &pool->idle_list); + + if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) + mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); + + /* Sanity check nr_running. */ + WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); +} + +/** + * worker_leave_idle - leave idle state + * @worker: worker which is leaving idle state + * + * @worker is leaving idle state. Update stats. + * + * LOCKING: + * raw_spin_lock_irq(pool->lock). + */ +static void worker_leave_idle(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + + if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) + return; + worker_clr_flags(worker, WORKER_IDLE); + pool->nr_idle--; + list_del_init(&worker->entry); +} + +/** + * find_worker_executing_work - find worker which is executing a work + * @pool: pool of interest + * @work: work to find worker for + * + * Find a worker which is executing @work on @pool by searching + * @pool->busy_hash which is keyed by the address of @work. For a worker + * to match, its current execution should match the address of @work and + * its work function. This is to avoid unwanted dependency between + * unrelated work executions through a work item being recycled while still + * being executed. + * + * This is a bit tricky. A work item may be freed once its execution + * starts and nothing prevents the freed area from being recycled for + * another work item. If the same work item address ends up being reused + * before the original execution finishes, workqueue will identify the + * recycled work item as currently executing and make it wait until the + * current execution finishes, introducing an unwanted dependency. + * + * This function checks the work item address and work function to avoid + * false positives. Note that this isn't complete as one may construct a + * work function which can introduce dependency onto itself through a + * recycled work item. Well, if somebody wants to shoot oneself in the + * foot that badly, there's only so much we can do, and if such deadlock + * actually occurs, it should be easy to locate the culprit work function. + * + * CONTEXT: + * raw_spin_lock_irq(pool->lock). + * + * Return: + * Pointer to worker which is executing @work if found, %NULL + * otherwise. + */ +static struct worker *find_worker_executing_work(struct worker_pool *pool, + struct work_struct *work) +{ + struct worker *worker; + + hash_for_each_possible(pool->busy_hash, worker, hentry, + (unsigned long)work) + if (worker->current_work == work && + worker->current_func == work->func) + return worker; + + return NULL; +} + +/** + * move_linked_works - move linked works to a list + * @work: start of series of works to be scheduled + * @head: target list to append @work to + * @nextp: out parameter for nested worklist walking + * + * Schedule linked works starting from @work to @head. Work series to be + * scheduled starts at @work and includes any consecutive work with + * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on + * @nextp. + * + * CONTEXT: + * raw_spin_lock_irq(pool->lock). + */ +static void move_linked_works(struct work_struct *work, struct list_head *head, + struct work_struct **nextp) +{ + struct work_struct *n; + + /* + * Linked worklist will always end before the end of the list, + * use NULL for list head. + */ + list_for_each_entry_safe_from(work, n, NULL, entry) { + list_move_tail(&work->entry, head); + if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) + break; + } + + /* + * If we're already inside safe list traversal and have moved + * multiple works to the scheduled queue, the next position + * needs to be updated. + */ + if (nextp) + *nextp = n; +} + +/** + * assign_work - assign a work item and its linked work items to a worker + * @work: work to assign + * @worker: worker to assign to + * @nextp: out parameter for nested worklist walking + * + * Assign @work and its linked work items to @worker. If @work is already being + * executed by another worker in the same pool, it'll be punted there. + * + * If @nextp is not NULL, it's updated to point to the next work of the last + * scheduled work. This allows assign_work() to be nested inside + * list_for_each_entry_safe(). + * + * Returns %true if @work was successfully assigned to @worker. %false if @work + * was punted to another worker already executing it. + */ +static bool assign_work(struct work_struct *work, struct worker *worker, + struct work_struct **nextp) +{ + struct worker_pool *pool = worker->pool; + struct worker *collision; + + lockdep_assert_held(&pool->lock); + + /* + * A single work shouldn't be executed concurrently by multiple workers. + * __queue_work() ensures that @work doesn't jump to a different pool + * while still running in the previous pool. Here, we should ensure that + * @work is not executed concurrently by multiple workers from the same + * pool. Check whether anyone is already processing the work. If so, + * defer the work to the currently executing one. + */ + collision = find_worker_executing_work(pool, work); + if (unlikely(collision)) { + move_linked_works(work, &collision->scheduled, nextp); + return false; + } + + move_linked_works(work, &worker->scheduled, nextp); + return true; +} + +/** + * kick_pool - wake up an idle worker if necessary + * @pool: pool to kick + * + * @pool may have pending work items. Wake up worker if necessary. Returns + * whether a worker was woken up. + */ +static bool kick_pool(struct worker_pool *pool) +{ + struct worker *worker = first_idle_worker(pool); + struct task_struct *p; + + lockdep_assert_held(&pool->lock); + + if (!need_more_worker(pool) || !worker) + return false; + + p = worker->task; + +#ifdef CONFIG_SMP + /* + * Idle @worker is about to execute @work and waking up provides an + * opportunity to migrate @worker at a lower cost by setting the task's + * wake_cpu field. Let's see if we want to move @worker to improve + * execution locality. + * + * We're waking the worker that went idle the latest and there's some + * chance that @worker is marked idle but hasn't gone off CPU yet. If + * so, setting the wake_cpu won't do anything. As this is a best-effort + * optimization and the race window is narrow, let's leave as-is for + * now. If this becomes pronounced, we can skip over workers which are + * still on cpu when picking an idle worker. + * + * If @pool has non-strict affinity, @worker might have ended up outside + * its affinity scope. Repatriate. + */ + if (!pool->attrs->affn_strict && + !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) { + struct work_struct *work = list_first_entry(&pool->worklist, + struct work_struct, entry); + p->wake_cpu = cpumask_any_distribute(pool->attrs->__pod_cpumask); + get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++; + } +#endif + wake_up_process(p); + return true; +} + #ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT /* @@ -1120,10 +1308,9 @@ void wq_worker_sleeping(struct task_struct *task) } pool->nr_running--; - if (need_more_worker(pool)) { + if (kick_pool(pool)) worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++; - wake_up_worker(pool); - } + raw_spin_unlock_irq(&pool->lock); } @@ -1171,10 +1358,8 @@ void wq_worker_tick(struct task_struct *task) wq_cpu_intensive_report(worker->current_func); pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; - if (need_more_worker(pool)) { + if (kick_pool(pool)) pwq->stats[PWQ_STAT_CM_WAKEUP]++; - wake_up_worker(pool); - } raw_spin_unlock(&pool->lock); } @@ -1211,94 +1396,6 @@ work_func_t wq_worker_last_func(struct task_struct *task) } /** - * find_worker_executing_work - find worker which is executing a work - * @pool: pool of interest - * @work: work to find worker for - * - * Find a worker which is executing @work on @pool by searching - * @pool->busy_hash which is keyed by the address of @work. For a worker - * to match, its current execution should match the address of @work and - * its work function. This is to avoid unwanted dependency between - * unrelated work executions through a work item being recycled while still - * being executed. - * - * This is a bit tricky. A work item may be freed once its execution - * starts and nothing prevents the freed area from being recycled for - * another work item. If the same work item address ends up being reused - * before the original execution finishes, workqueue will identify the - * recycled work item as currently executing and make it wait until the - * current execution finishes, introducing an unwanted dependency. - * - * This function checks the work item address and work function to avoid - * false positives. Note that this isn't complete as one may construct a - * work function which can introduce dependency onto itself through a - * recycled work item. Well, if somebody wants to shoot oneself in the - * foot that badly, there's only so much we can do, and if such deadlock - * actually occurs, it should be easy to locate the culprit work function. - * - * CONTEXT: - * raw_spin_lock_irq(pool->lock). - * - * Return: - * Pointer to worker which is executing @work if found, %NULL - * otherwise. - */ -static struct worker *find_worker_executing_work(struct worker_pool *pool, - struct work_struct *work) -{ - struct worker *worker; - - hash_for_each_possible(pool->busy_hash, worker, hentry, - (unsigned long)work) - if (worker->current_work == work && - worker->current_func == work->func) - return worker; - - return NULL; -} - -/** - * move_linked_works - move linked works to a list - * @work: start of series of works to be scheduled - * @head: target list to append @work to - * @nextp: out parameter for nested worklist walking - * - * Schedule linked works starting from @work to @head. Work series to - * be scheduled starts at @work and includes any consecutive work with - * WORK_STRUCT_LINKED set in its predecessor. - * - * If @nextp is not NULL, it's updated to point to the next work of - * the last scheduled work. This allows move_linked_works() to be - * nested inside outer list_for_each_entry_safe(). - * - * CONTEXT: - * raw_spin_lock_irq(pool->lock). - */ -static void move_linked_works(struct work_struct *work, struct list_head *head, - struct work_struct **nextp) -{ - struct work_struct *n; - - /* - * Linked worklist will always end before the end of the list, - * use NULL for list head. - */ - list_for_each_entry_safe_from(work, n, NULL, entry) { - list_move_tail(&work->entry, head); - if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) - break; - } - - /* - * If we're already inside safe list traversal and have moved - * multiple works to the scheduled queue, the next position - * needs to be updated. - */ - if (nextp) - *nextp = n; -} - -/** * get_pwq - get an extra reference on the specified pool_workqueue * @pwq: pool_workqueue to get * @@ -1324,17 +1421,11 @@ static void put_pwq(struct pool_workqueue *pwq) lockdep_assert_held(&pwq->pool->lock); if (likely(--pwq->refcnt)) return; - if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) - return; /* - * @pwq can't be released under pool->lock, bounce to - * pwq_unbound_release_workfn(). This never recurses on the same - * pool->lock as this path is taken only for unbound workqueues and - * the release work item is scheduled on a per-cpu workqueue. To - * avoid lockdep warning, unbound pool->locks are given lockdep - * subclass of 1 in get_unbound_pool(). + * @pwq can't be released under pool->lock, bounce to a dedicated + * kthread_worker to avoid A-A deadlocks. */ - schedule_work(&pwq->unbound_release_work); + kthread_queue_work(pwq_release_worker, &pwq->release_work); } /** @@ -1550,7 +1641,7 @@ fail: static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, struct list_head *head, unsigned int extra_flags) { - struct worker_pool *pool = pwq->pool; + debug_work_activate(work); /* record the work call stack in order to print it in KASAN reports */ kasan_record_aux_stack_noalloc(work); @@ -1559,9 +1650,6 @@ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, set_work_pwq(work, pwq, extra_flags); list_add_tail(&work->entry, head); get_pwq(pwq); - - if (__need_more_worker(pool)) - wake_up_worker(pool); } /* @@ -1615,8 +1703,7 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, struct work_struct *work) { struct pool_workqueue *pwq; - struct worker_pool *last_pool; - struct list_head *worklist; + struct worker_pool *last_pool, *pool; unsigned int work_flags; unsigned int req_cpu = cpu; @@ -1640,23 +1727,23 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, rcu_read_lock(); retry: /* pwq which will be used unless @work is executing elsewhere */ - if (wq->flags & WQ_UNBOUND) { - if (req_cpu == WORK_CPU_UNBOUND) + if (req_cpu == WORK_CPU_UNBOUND) { + if (wq->flags & WQ_UNBOUND) cpu = wq_select_unbound_cpu(raw_smp_processor_id()); - pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); - } else { - if (req_cpu == WORK_CPU_UNBOUND) + else cpu = raw_smp_processor_id(); - pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); } + pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu)); + pool = pwq->pool; + /* * If @work was previously on a different pool, it might still be * running there, in which case the work needs to be queued on that * pool to guarantee non-reentrancy. */ last_pool = get_work_pool(work); - if (last_pool && last_pool != pwq->pool) { + if (last_pool && last_pool != pool) { struct worker *worker; raw_spin_lock(&last_pool->lock); @@ -1665,26 +1752,27 @@ retry: if (worker && worker->current_pwq->wq == wq) { pwq = worker->current_pwq; + pool = pwq->pool; + WARN_ON_ONCE(pool != last_pool); } else { /* meh... not running there, queue here */ raw_spin_unlock(&last_pool->lock); - raw_spin_lock(&pwq->pool->lock); + raw_spin_lock(&pool->lock); } } else { - raw_spin_lock(&pwq->pool->lock); + raw_spin_lock(&pool->lock); } /* - * pwq is determined and locked. For unbound pools, we could have - * raced with pwq release and it could already be dead. If its - * refcnt is zero, repeat pwq selection. Note that pwqs never die - * without another pwq replacing it in the numa_pwq_tbl or while - * work items are executing on it, so the retrying is guaranteed to - * make forward-progress. + * pwq is determined and locked. For unbound pools, we could have raced + * with pwq release and it could already be dead. If its refcnt is zero, + * repeat pwq selection. Note that unbound pwqs never die without + * another pwq replacing it in cpu_pwq or while work items are executing + * on it, so the retrying is guaranteed to make forward-progress. */ if (unlikely(!pwq->refcnt)) { if (wq->flags & WQ_UNBOUND) { - raw_spin_unlock(&pwq->pool->lock); + raw_spin_unlock(&pool->lock); cpu_relax(); goto retry; } @@ -1703,21 +1791,20 @@ retry: work_flags = work_color_to_flags(pwq->work_color); if (likely(pwq->nr_active < pwq->max_active)) { + if (list_empty(&pool->worklist)) + pool->watchdog_ts = jiffies; + trace_workqueue_activate_work(work); pwq->nr_active++; - worklist = &pwq->pool->worklist; - if (list_empty(worklist)) - pwq->pool->watchdog_ts = jiffies; + insert_work(pwq, work, &pool->worklist, work_flags); + kick_pool(pool); } else { work_flags |= WORK_STRUCT_INACTIVE; - worklist = &pwq->inactive_works; + insert_work(pwq, work, &pwq->inactive_works, work_flags); } - debug_work_activate(work); - insert_work(pwq, work, worklist, work_flags); - out: - raw_spin_unlock(&pwq->pool->lock); + raw_spin_unlock(&pool->lock); rcu_read_unlock(); } @@ -1754,7 +1841,7 @@ bool queue_work_on(int cpu, struct workqueue_struct *wq, EXPORT_SYMBOL(queue_work_on); /** - * workqueue_select_cpu_near - Select a CPU based on NUMA node + * select_numa_node_cpu - Select a CPU based on NUMA node * @node: NUMA node ID that we want to select a CPU from * * This function will attempt to find a "random" cpu available on a given @@ -1762,14 +1849,10 @@ EXPORT_SYMBOL(queue_work_on); * WORK_CPU_UNBOUND indicating that we should just schedule to any * available CPU if we need to schedule this work. */ -static int workqueue_select_cpu_near(int node) +static int select_numa_node_cpu(int node) { int cpu; - /* No point in doing this if NUMA isn't enabled for workqueues */ - if (!wq_numa_enabled) - return WORK_CPU_UNBOUND; - /* Delay binding to CPU if node is not valid or online */ if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) return WORK_CPU_UNBOUND; @@ -1826,7 +1909,7 @@ bool queue_work_node(int node, struct workqueue_struct *wq, local_irq_save(flags); if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { - int cpu = workqueue_select_cpu_near(node); + int cpu = select_numa_node_cpu(node); __queue_work(cpu, wq, work); ret = true; @@ -1981,60 +2064,6 @@ bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) } EXPORT_SYMBOL(queue_rcu_work); -/** - * worker_enter_idle - enter idle state - * @worker: worker which is entering idle state - * - * @worker is entering idle state. Update stats and idle timer if - * necessary. - * - * LOCKING: - * raw_spin_lock_irq(pool->lock). - */ -static void worker_enter_idle(struct worker *worker) -{ - struct worker_pool *pool = worker->pool; - - if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || - WARN_ON_ONCE(!list_empty(&worker->entry) && - (worker->hentry.next || worker->hentry.pprev))) - return; - - /* can't use worker_set_flags(), also called from create_worker() */ - worker->flags |= WORKER_IDLE; - pool->nr_idle++; - worker->last_active = jiffies; - - /* idle_list is LIFO */ - list_add(&worker->entry, &pool->idle_list); - - if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) - mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); - - /* Sanity check nr_running. */ - WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); -} - -/** - * worker_leave_idle - leave idle state - * @worker: worker which is leaving idle state - * - * @worker is leaving idle state. Update stats. - * - * LOCKING: - * raw_spin_lock_irq(pool->lock). - */ -static void worker_leave_idle(struct worker *worker) -{ - struct worker_pool *pool = worker->pool; - - if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) - return; - worker_clr_flags(worker, WORKER_IDLE); - pool->nr_idle--; - list_del_init(&worker->entry); -} - static struct worker *alloc_worker(int node) { struct worker *worker; @@ -2050,6 +2079,14 @@ static struct worker *alloc_worker(int node) return worker; } +static cpumask_t *pool_allowed_cpus(struct worker_pool *pool) +{ + if (pool->cpu < 0 && pool->attrs->affn_strict) + return pool->attrs->__pod_cpumask; + else + return pool->attrs->cpumask; +} + /** * worker_attach_to_pool() - attach a worker to a pool * @worker: worker to be attached @@ -2075,7 +2112,7 @@ static void worker_attach_to_pool(struct worker *worker, kthread_set_per_cpu(worker->task, pool->cpu); if (worker->rescue_wq) - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool)); list_add_tail(&worker->node, &pool->workers); worker->pool = pool; @@ -2167,16 +2204,25 @@ static struct worker *create_worker(struct worker_pool *pool) } set_user_nice(worker->task, pool->attrs->nice); - kthread_bind_mask(worker->task, pool->attrs->cpumask); + kthread_bind_mask(worker->task, pool_allowed_cpus(pool)); /* successful, attach the worker to the pool */ worker_attach_to_pool(worker, pool); /* start the newly created worker */ raw_spin_lock_irq(&pool->lock); + worker->pool->nr_workers++; worker_enter_idle(worker); + kick_pool(pool); + + /* + * @worker is waiting on a completion in kthread() and will trigger hung + * check if not woken up soon. As kick_pool() might not have waken it + * up, wake it up explicitly once more. + */ wake_up_process(worker->task); + raw_spin_unlock_irq(&pool->lock); return worker; @@ -2304,9 +2350,8 @@ static void idle_worker_timeout(struct timer_list *t) static void idle_cull_fn(struct work_struct *work) { struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); - struct list_head cull_list; + LIST_HEAD(cull_list); - INIT_LIST_HEAD(&cull_list); /* * Grabbing wq_pool_attach_mutex here ensures an already-running worker * cannot proceed beyong worker_detach_from_pool() in its self-destruct @@ -2495,7 +2540,6 @@ __acquires(&pool->lock) struct pool_workqueue *pwq = get_work_pwq(work); struct worker_pool *pool = worker->pool; unsigned long work_data; - struct worker *collision; #ifdef CONFIG_LOCKDEP /* * It is permissible to free the struct work_struct from @@ -2512,18 +2556,6 @@ __acquires(&pool->lock) WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && raw_smp_processor_id() != pool->cpu); - /* - * A single work shouldn't be executed concurrently by - * multiple workers on a single cpu. Check whether anyone is - * already processing the work. If so, defer the work to the - * currently executing one. - */ - collision = find_worker_executing_work(pool, work); - if (unlikely(collision)) { - move_linked_works(work, &collision->scheduled, NULL); - return; - } - /* claim and dequeue */ debug_work_deactivate(work); hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); @@ -2552,14 +2584,12 @@ __acquires(&pool->lock) worker_set_flags(worker, WORKER_CPU_INTENSIVE); /* - * Wake up another worker if necessary. The condition is always - * false for normal per-cpu workers since nr_running would always - * be >= 1 at this point. This is used to chain execution of the - * pending work items for WORKER_NOT_RUNNING workers such as the - * UNBOUND and CPU_INTENSIVE ones. + * Kick @pool if necessary. It's always noop for per-cpu worker pools + * since nr_running would always be >= 1 at this point. This is used to + * chain execution of the pending work items for WORKER_NOT_RUNNING + * workers such as the UNBOUND and CPU_INTENSIVE ones. */ - if (need_more_worker(pool)) - wake_up_worker(pool); + kick_pool(pool); /* * Record the last pool and clear PENDING which should be the last @@ -2569,6 +2599,7 @@ __acquires(&pool->lock) */ set_work_pool_and_clear_pending(work, pool->id); + pwq->stats[PWQ_STAT_STARTED]++; raw_spin_unlock_irq(&pool->lock); lock_map_acquire(&pwq->wq->lockdep_map); @@ -2595,7 +2626,6 @@ __acquires(&pool->lock) * workqueues), so hiding them isn't a problem. */ lockdep_invariant_state(true); - pwq->stats[PWQ_STAT_STARTED]++; trace_workqueue_execute_start(work); worker->current_func(work); /* @@ -2661,9 +2691,15 @@ __acquires(&pool->lock) */ static void process_scheduled_works(struct worker *worker) { - while (!list_empty(&worker->scheduled)) { - struct work_struct *work = list_first_entry(&worker->scheduled, - struct work_struct, entry); + struct work_struct *work; + bool first = true; + + while ((work = list_first_entry_or_null(&worker->scheduled, + struct work_struct, entry))) { + if (first) { + worker->pool->watchdog_ts = jiffies; + first = false; + } process_one_work(worker, work); } } @@ -2744,17 +2780,8 @@ recheck: list_first_entry(&pool->worklist, struct work_struct, entry); - pool->watchdog_ts = jiffies; - - if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { - /* optimization path, not strictly necessary */ - process_one_work(worker, work); - if (unlikely(!list_empty(&worker->scheduled))) - process_scheduled_works(worker); - } else { - move_linked_works(work, &worker->scheduled, NULL); + if (assign_work(work, worker, NULL)) process_scheduled_works(worker); - } } while (keep_working(pool)); worker_set_flags(worker, WORKER_PREP); @@ -2798,7 +2825,6 @@ static int rescuer_thread(void *__rescuer) { struct worker *rescuer = __rescuer; struct workqueue_struct *wq = rescuer->rescue_wq; - struct list_head *scheduled = &rescuer->scheduled; bool should_stop; set_user_nice(current, RESCUER_NICE_LEVEL); @@ -2829,7 +2855,6 @@ repeat: struct pool_workqueue, mayday_node); struct worker_pool *pool = pwq->pool; struct work_struct *work, *n |