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media: coda: fix deadlock between decoder picture run and start command 

commit a3fd80198d upstream.

The BIT decoder picture run temporarily locks the bitstream mutex while
the coda device mutex is locked, to refill the bitstream ring buffer.
Consequently, the decoder start command, which locks both mutexes when
flushing the bitstream ring buffer, must lock the coda device mutex
first as well, to avoid an ABBA deadlock.

Fixes: e7fd95849b ("media: coda: flush bitstream ring buffer on decoder restart")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
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>
This commit is contained in:
Philipp Zabel 2019-10-24 07:32:11 -03:00 committed by Greg Kroah-Hartman
parent 7eab724d4a
commit 03915a22e8
1 changed files with 2 additions and 2 deletions
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4
drivers/media/platform/coda/coda-common.c
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@ -1084,16 +1084,16 @@ static int coda_decoder_cmd(struct file *file, void *fh,
switch (dc->cmd) {
case V4L2_DEC_CMD_START:
mutex_lock(&ctx->bitstream_mutex);
mutex_lock(&dev->coda_mutex);
mutex_lock(&ctx->bitstream_mutex);
coda_bitstream_flush(ctx);
mutex_unlock(&dev->coda_mutex);
dst_vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx,
V4L2_BUF_TYPE_VIDEO_CAPTURE);
vb2_clear_last_buffer_dequeued(dst_vq);
ctx->bit_stream_param &= ~CODA_BIT_STREAM_END_FLAG;
coda_fill_bitstream(ctx, NULL);
mutex_unlock(&ctx->bitstream_mutex);
mutex_unlock(&dev->coda_mutex);
break;
case V4L2_DEC_CMD_STOP:
stream_end = false;