diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 79 |
1 files changed, 24 insertions, 55 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5557d19ea81c..33f1106b4f99 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -154,6 +154,9 @@ struct worker_pool { unsigned long watchdog_ts; /* L: watchdog timestamp */ + /* The current concurrency level. */ + atomic_t nr_running; + struct list_head worklist; /* L: list of pending works */ int nr_workers; /* L: total number of workers */ @@ -178,18 +181,11 @@ struct worker_pool { int refcnt; /* PL: refcnt for unbound pools */ /* - * The current concurrency level. As it's likely to be accessed - * from other CPUs during try_to_wake_up(), put it in a separate - * cacheline. - */ - atomic_t nr_running ____cacheline_aligned_in_smp; - - /* * Destruction of pool is RCU protected to allow dereferences * from get_work_pool(). */ struct rcu_head rcu; -} ____cacheline_aligned_in_smp; +}; /* * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS @@ -887,8 +883,7 @@ void wq_worker_running(struct task_struct *task) * @task: task going to sleep * * This function is called from schedule() when a busy worker is - * going to sleep. Preemption needs to be disabled to protect ->sleeping - * assignment. + * going to sleep. */ void wq_worker_sleeping(struct task_struct *task) { @@ -1831,14 +1826,8 @@ static void worker_enter_idle(struct worker *worker) if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); - /* - * Sanity check nr_running. Because unbind_workers() releases - * pool->lock between setting %WORKER_UNBOUND and zapping - * nr_running, the warning may trigger spuriously. Check iff - * unbind is not in progress. - */ - WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && - pool->nr_workers == pool->nr_idle && + /* Sanity check nr_running. */ + WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && atomic_read(&pool->nr_running)); } @@ -4999,38 +4988,22 @@ static void unbind_workers(int cpu) /* * We've blocked all attach/detach operations. Make all workers * unbound and set DISASSOCIATED. Before this, all workers - * except for the ones which are still executing works from - * before the last CPU down must be on the cpu. After - * this, they may become diasporas. + * must be on the cpu. After this, they may become diasporas. + * And the preemption disabled section in their sched callbacks + * are guaranteed to see WORKER_UNBOUND since the code here + * is on the same cpu. */ for_each_pool_worker(worker, pool) worker->flags |= WORKER_UNBOUND; pool->flags |= POOL_DISASSOCIATED; - raw_spin_unlock_irq(&pool->lock); - - for_each_pool_worker(worker, pool) { - kthread_set_per_cpu(worker->task, -1); - WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); - } - - mutex_unlock(&wq_pool_attach_mutex); - - /* - * Call schedule() so that we cross rq->lock and thus can - * guarantee sched callbacks see the %WORKER_UNBOUND flag. - * This is necessary as scheduler callbacks may be invoked - * from other cpus. - */ - schedule(); - /* - * 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. This pool now behaves as an - * unbound (in terms of concurrency management) pool which + * The handling of nr_running in 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. This pool now behaves as + * an unbound (in terms of concurrency management) pool which * are served by workers tied to the pool. */ atomic_set(&pool->nr_running, 0); @@ -5040,9 +5013,16 @@ static void unbind_workers(int cpu) * worker blocking could lead to lengthy stalls. Kick off * unbound chain execution of currently pending work items. */ - raw_spin_lock_irq(&pool->lock); wake_up_worker(pool); + raw_spin_unlock_irq(&pool->lock); + + for_each_pool_worker(worker, pool) { + kthread_set_per_cpu(worker->task, -1); + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); + } + + mutex_unlock(&wq_pool_attach_mutex); } } @@ -5079,17 +5059,6 @@ static void rebind_workers(struct worker_pool *pool) unsigned int worker_flags = worker->flags; /* - * A bound idle worker should actually be on the runqueue - * of the associated CPU for local wake-ups targeting it to - * work. Kick all idle workers so that they migrate to the - * associated CPU. Doing this in the same loop as - * replacing UNBOUND with REBOUND is safe as no worker will - * be bound before @pool->lock is released. - */ - if (worker_flags & WORKER_IDLE) - wake_up_process(worker->task); - - /* * We want to clear UNBOUND but can't directly call * worker_clr_flags() or adjust nr_running. Atomically * replace UNBOUND with another NOT_RUNNING flag REBOUND. |