From f2d5a0ee06c1813f985bb9386f3ccc0d0315720f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 17 Jul 2012 12:39:26 -0700 Subject: [PATCH] workqueue: drop CPU_DYING notifier operation Workqueue used CPU_DYING notification to mark GCWQ_DISASSOCIATED. This was necessary because workqueue's CPU_DOWN_PREPARE happened before other DOWN_PREPARE notifiers and workqueue needed to stay associated across the rest of DOWN_PREPARE. After the previous patch, workqueue's DOWN_PREPARE happens after others and can set GCWQ_DISASSOCIATED directly. Drop CPU_DYING and let the trustee set GCWQ_DISASSOCIATED after disabling concurrency management. Signed-off-by: Tejun Heo Acked-by: "Rafael J. Wysocki" --- kernel/workqueue.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f59b7fd26e26..1405fb98c0b1 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1250,11 +1250,11 @@ static void worker_leave_idle(struct worker *worker) * verbatim as it's best effort and blocking and gcwq may be * [dis]associated in the meantime. * - * This function tries set_cpus_allowed() and locks gcwq and verifies - * the binding against GCWQ_DISASSOCIATED which is set during - * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters - * idle state or fetches works without dropping lock, it can guarantee - * the scheduling requirement described in the first paragraph. + * This function tries set_cpus_allowed() and locks gcwq and verifies the + * binding against %GCWQ_DISASSOCIATED which is set during + * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker + * enters idle state or fetches works without dropping lock, it can + * guarantee the scheduling requirement described in the first paragraph. * * CONTEXT: * Might sleep. Called without any lock but returns with gcwq->lock @@ -3349,6 +3349,12 @@ static int __cpuinit trustee_thread(void *__gcwq) rc = trustee_wait_event(!gcwq_is_managing_workers(gcwq)); BUG_ON(rc < 0); + /* + * We've claimed all manager positions. 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. + */ for_each_worker_pool(pool, gcwq) { pool->flags |= POOL_MANAGING_WORKERS; @@ -3359,6 +3365,8 @@ static int __cpuinit trustee_thread(void *__gcwq) for_each_busy_worker(worker, i, pos, gcwq) worker->flags |= WORKER_ROGUE; + gcwq->flags |= GCWQ_DISASSOCIATED; + /* * Call schedule() so that we cross rq->lock and thus can * guarantee sched callbacks see the rogue flag. This is @@ -3582,16 +3590,6 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, } break; - case CPU_DYING: - /* - * Before this, the trustee and 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'll all be diasporas. - */ - gcwq->flags |= GCWQ_DISASSOCIATED; - break; - case CPU_POST_DEAD: gcwq->trustee_state = TRUSTEE_BUTCHER; /* fall through */ @@ -3672,7 +3670,6 @@ static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, { switch (action & ~CPU_TASKS_FROZEN) { case CPU_DOWN_PREPARE: - case CPU_DYING: case CPU_POST_DEAD: return workqueue_cpu_callback(nfb, action, hcpu); } -- 2.20.1