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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2012-09-18 09:59:22 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2012-09-18 09:59:22 -0700 |
| commit | eab6d82843ee1df244f8847d1bf8bb89160ec4aa (patch) | |
| tree | 86a43e6ae1734779fe54ea5e62408395e6d0b36a /kernel/workqueue.c | |
| parent | ea1abd6197d5805655da1bb589929762f4b4aa08 (diff) | |
| download | linux-eab6d82843ee1df244f8847d1bf8bb89160ec4aa.tar.gz | |
workqueue: WORKER_REBIND is no longer necessary for busy rebinding
Because the old unbind/rebinding implementation wasn't atomic w.r.t. GCWQ_DISASSOCIATED manipulation which is protected by global_cwq->lock, we had to use two flags, WORKER_UNBOUND and WORKER_REBIND, to avoid incorrectly losing all NOT_RUNNING bits with back-to-back CPU hotplug operations; otherwise, completion of rebinding while another unbinding is in progress could clear UNBIND prematurely. Now that both unbind/rebinding are atomic w.r.t. GCWQ_DISASSOCIATED, there's no need to use two flags. Just one is enough. Don't use WORKER_REBIND for busy rebinding. tj: Updated description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 770c1a8128bf..794724efb733 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1649,16 +1649,8 @@ 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; - 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); } @@ -1721,15 +1713,9 @@ static void rebind_workers(struct global_cwq *gcwq) /* 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; |