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Subject[PATCH 6.0 169/862] media: cedrus: Fix watchdog race condition
Date
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>

commit fe8b81fde69acfcbb5af9e85328e5b9549999fdb upstream.

The watchdog needs to be scheduled before we trigger the decode
operation, otherwise there is a risk that the decoder IRQ will be
called before we have schedule the watchdog. As a side effect, the
watchdog would never be cancelled and its function would be called
at an inappropriate time.

This was observed while running Fluster with GStreamer as a backend.
Some programming error would cause the decoder IRQ to be call very
quickly after the trigger. Later calls into the driver would deadlock
due to the unbalanced state.

Cc: stable@vger.kernel.org
Fixes: 7c38a551bda1 ("media: cedrus: Add watchdog for job completion")
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
@@ -106,11 +106,11 @@ void cedrus_device_run(void *priv)

/* Trigger decoding if setup went well, bail out otherwise. */
if (!error) {
- dev->dec_ops[ctx->current_codec]->trigger(ctx);
-
/* Start the watchdog timer. */
schedule_delayed_work(&dev->watchdog_work,
msecs_to_jiffies(2000));
+
+ dev->dec_ops[ctx->current_codec]->trigger(ctx);
} else {
v4l2_m2m_buf_done_and_job_finish(ctx->dev->m2m_dev,
ctx->fh.m2m_ctx,

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