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kthread_worker: split code for canceling the delayed work timer
commit 34b3d53447
upstream.
Patch series "kthread_worker: Fix race between kthread_mod_delayed_work()
and kthread_cancel_delayed_work_sync()".
This patchset fixes the race between kthread_mod_delayed_work() and
kthread_cancel_delayed_work_sync() including proper return value
handling.
This patch (of 2):
Simple code refactoring as a preparation step for fixing a race between
kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync().
It does not modify the existing behavior.
Link: https://lkml.kernel.org/r/20210610133051.15337-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: <jenhaochen@google.com>
Cc: Martin Liu <liumartin@google.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
22226752e4
commit
392cfdd660
1 changed files with 29 additions and 17 deletions
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@ -951,6 +951,33 @@ void kthread_flush_work(struct kthread_work *work)
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}
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EXPORT_SYMBOL_GPL(kthread_flush_work);
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/*
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* Make sure that the timer is neither set nor running and could
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* not manipulate the work list_head any longer.
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*
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* The function is called under worker->lock. The lock is temporary
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* released but the timer can't be set again in the meantime.
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*/
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static void kthread_cancel_delayed_work_timer(struct kthread_work *work,
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unsigned long *flags)
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{
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struct kthread_delayed_work *dwork =
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container_of(work, struct kthread_delayed_work, work);
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struct kthread_worker *worker = work->worker;
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/*
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* del_timer_sync() must be called to make sure that the timer
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* callback is not running. The lock must be temporary released
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* to avoid a deadlock with the callback. In the meantime,
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* any queuing is blocked by setting the canceling counter.
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*/
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work->canceling++;
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spin_unlock_irqrestore(&worker->lock, *flags);
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del_timer_sync(&dwork->timer);
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spin_lock_irqsave(&worker->lock, *flags);
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work->canceling--;
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}
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/*
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* This function removes the work from the worker queue. Also it makes sure
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* that it won't get queued later via the delayed work's timer.
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@ -965,23 +992,8 @@ static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
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unsigned long *flags)
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{
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/* Try to cancel the timer if exists. */
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if (is_dwork) {
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struct kthread_delayed_work *dwork =
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container_of(work, struct kthread_delayed_work, work);
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struct kthread_worker *worker = work->worker;
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/*
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* del_timer_sync() must be called to make sure that the timer
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* callback is not running. The lock must be temporary released
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* to avoid a deadlock with the callback. In the meantime,
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* any queuing is blocked by setting the canceling counter.
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*/
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work->canceling++;
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spin_unlock_irqrestore(&worker->lock, *flags);
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del_timer_sync(&dwork->timer);
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spin_lock_irqsave(&worker->lock, *flags);
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work->canceling--;
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}
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if (is_dwork)
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kthread_cancel_delayed_work_timer(work, flags);
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/*
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* Try to remove the work from a worker list. It might either
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