This is a note to let you know that I've just added the patch titled
media: cec-adap.c: don't use flush_scheduled_work()
to the 5.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-cec-adap.c-don-t-use-flush_scheduled_work.patch
and it can be found in the queue-5.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 288eceb0858323d66bff03cf386630a797b248ad Mon Sep 17 00:00:00 2001
From: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Date: Tue, 8 Sep 2020 12:02:53 +0200
Subject: media: cec-adap.c: don't use flush_scheduled_work()
From: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
commit 288eceb0858323d66bff03cf386630a797b248ad upstream.
For some inexplicable reason I decided to call flush_scheduled_work()
instead of cancel_delayed_work_sync(). The problem with that is that
flush_scheduled_work() waits for *all* queued scheduled work to be
completed instead of just the work itself.
This can cause a deadlock if a CEC driver also schedules work that
takes the same lock. See the comments for flush_scheduled_work() in
linux/workqueue.h.
This is exactly what has been observed a few times.
This patch simply replaces flush_scheduled_work() by
cancel_delayed_work_sync().
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # for v5.8 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/cec/core/cec-adap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/media/cec/core/cec-adap.c
+++ b/drivers/media/cec/core/cec-adap.c
@@ -1199,7 +1199,7 @@ void cec_received_msg_ts(struct cec_adap
/* Cancel the pending timeout work */
if (!cancel_delayed_work(&data->work)) {
mutex_unlock(&adap->lock);
- flush_scheduled_work();
+ cancel_delayed_work_sync(&data->work);
mutex_lock(&adap->lock);
}
/*
Patches currently in stable-queue which might be from hverkuil-cisco@xxxxxxxxx are
queue-5.8/media-cec-adap.c-don-t-use-flush_scheduled_work.patch
