| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 19/48] kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled | Date | Mon, 9 Nov 2020 13:55:28 +0100 |
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From: Zqiang <qiang.zhang@windriver.com>
commit 6993d0fdbee0eb38bfac350aa016f65ad11ed3b1 upstream.
There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn:
CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work();
BUG: kthread_insert_work() should not get called when work->canceling is set.
Signed-off-by: Zqiang <qiang.zhang@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -831,7 +831,8 @@ void kthread_delayed_work_timer_fn(unsig /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list); spin_unlock(&worker->lock); }
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