From: Petr Mladek <pmladek@suse.com> To: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>, Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Josh Triplett <josh@joshtriplett.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>, Michal Hocko <mhocko@suse.cz>, linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com> Subject: [PATCH v7 04/10] kthread: Add drain_kthread_worker() Date: Mon, 30 May 2016 16:59:25 +0200 [thread overview] Message-ID: <1464620371-31346-5-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1464620371-31346-1-git-send-email-pmladek@suse.com> flush_kthread_worker() returns when the currently queued works are proceed. But some other works might have been queued in the meantime. This patch adds drain_kthread_worker() that is inspired by drain_workqueue(). It returns when the queue is completely empty and warns when it takes too long. The initial implementation does not block queuing new works when draining. It makes things much easier. The blocking would be useful to debug potential problems but it is not clear if it is worth the complication at the moment. Signed-off-by: Petr Mladek <pmladek@suse.com> --- kernel/kthread.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/kernel/kthread.c b/kernel/kthread.c index 76364374ff98..6051aa9d93c6 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -818,3 +818,37 @@ void flush_kthread_worker(struct kthread_worker *worker) wait_for_completion(&fwork.done); } EXPORT_SYMBOL_GPL(flush_kthread_worker); + +/** + * drain_kthread_worker - drain a kthread worker + * @worker: worker to be drained + * + * Wait until there is no work queued for the given kthread worker. + * @worker is flushed repeatedly until it becomes empty. The number + * of flushing is determined by the depth of chaining and should + * be relatively short. Whine if it takes too long. + * + * The caller is responsible for blocking all users of this kthread + * worker from queuing new works. Also it is responsible for blocking + * the already queued works from an infinite re-queuing! + */ +void drain_kthread_worker(struct kthread_worker *worker) +{ + int flush_cnt = 0; + + spin_lock_irq(&worker->lock); + + while (!list_empty(&worker->work_list)) { + spin_unlock_irq(&worker->lock); + + flush_kthread_worker(worker); + WARN_ONCE(flush_cnt++ > 10, + "kthread worker %s: drain_kthread_worker() isn't complete after %u tries\n", + worker->task->comm, flush_cnt); + + spin_lock_irq(&worker->lock); + } + + spin_unlock_irq(&worker->lock); +} +EXPORT_SYMBOL(drain_kthread_worker); -- 1.8.5.6
WARNING: multiple messages have this Message-ID (diff)
From: Petr Mladek <pmladek@suse.com> To: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>, Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Josh Triplett <josh@joshtriplett.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>, Michal Hocko <mhocko@suse.cz>, linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com> Subject: [PATCH v7 04/10] kthread: Add drain_kthread_worker() Date: Mon, 30 May 2016 16:59:25 +0200 [thread overview] Message-ID: <1464620371-31346-5-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1464620371-31346-1-git-send-email-pmladek@suse.com> flush_kthread_worker() returns when the currently queued works are proceed. But some other works might have been queued in the meantime. This patch adds drain_kthread_worker() that is inspired by drain_workqueue(). It returns when the queue is completely empty and warns when it takes too long. The initial implementation does not block queuing new works when draining. It makes things much easier. The blocking would be useful to debug potential problems but it is not clear if it is worth the complication at the moment. Signed-off-by: Petr Mladek <pmladek@suse.com> --- kernel/kthread.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/kernel/kthread.c b/kernel/kthread.c index 76364374ff98..6051aa9d93c6 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -818,3 +818,37 @@ void flush_kthread_worker(struct kthread_worker *worker) wait_for_completion(&fwork.done); } EXPORT_SYMBOL_GPL(flush_kthread_worker); + +/** + * drain_kthread_worker - drain a kthread worker + * @worker: worker to be drained + * + * Wait until there is no work queued for the given kthread worker. + * @worker is flushed repeatedly until it becomes empty. The number + * of flushing is determined by the depth of chaining and should + * be relatively short. Whine if it takes too long. + * + * The caller is responsible for blocking all users of this kthread + * worker from queuing new works. Also it is responsible for blocking + * the already queued works from an infinite re-queuing! + */ +void drain_kthread_worker(struct kthread_worker *worker) +{ + int flush_cnt = 0; + + spin_lock_irq(&worker->lock); + + while (!list_empty(&worker->work_list)) { + spin_unlock_irq(&worker->lock); + + flush_kthread_worker(worker); + WARN_ONCE(flush_cnt++ > 10, + "kthread worker %s: drain_kthread_worker() isn't complete after %u tries\n", + worker->task->comm, flush_cnt); + + spin_lock_irq(&worker->lock); + } + + spin_unlock_irq(&worker->lock); +} +EXPORT_SYMBOL(drain_kthread_worker); -- 1.8.5.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-05-30 15:00 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-05-30 14:59 [PATCH v7 00/10] kthread: Kthread worker API improvements Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 01/10] kthread/smpboot: Do not park in kthread_create_on_cpu() Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 02/10] kthread: Allow to call __kthread_create_on_node() with va_list args Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 03/10] kthread: Add create_kthread_worker*() Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-06-01 19:36 ` Andrew Morton 2016-06-01 19:36 ` Andrew Morton 2016-06-01 19:36 ` Andrew Morton 2016-05-30 14:59 ` Petr Mladek [this message] 2016-05-30 14:59 ` [PATCH v7 04/10] kthread: Add drain_kthread_worker() Petr Mladek 2016-05-30 14:59 ` [PATCH v7 05/10] kthread: Add destroy_kthread_worker() Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 06/10] kthread: Detect when a kthread work is used by more workers Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 07/10] kthread: Initial support for delayed kthread work Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 08/10] kthread: Allow to cancel " Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 09/10] kthread: Allow to modify delayed " Petr Mladek 2016-05-30 14:59 ` Petr Mladek 2016-05-30 14:59 ` [PATCH v7 10/10] kthread: Better support freezable kthread workers Petr Mladek 2016-05-30 14:59 ` Petr Mladek
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