From: Alexandre Courbot gnurou@gmail.com
commit 566463afdbc43c7744c5a1b89250fc808df03833 upstream.
If poll() is called on a m2m device with the EPOLLOUT event after the last buffer of the CAPTURE queue is dequeued, any buffer available on OUTPUT queue will never be signaled because v4l2_m2m_poll_for_data() starts by checking whether dst_q->last_buffer_dequeued is set and returns EPOLLIN in this case, without looking at the state of the OUTPUT queue.
Fix this by not early returning so we keep checking the state of the OUTPUT queue afterwards.
Signed-off-by: Alexandre Courbot gnurou@gmail.com Reviewed-by: Ezequiel Garcia ezequiel@collabora.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Cc: Lecopzer Chen lecopzer.chen@mediatek.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/v4l2-core/v4l2-mem2mem.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c @@ -635,10 +635,8 @@ static __poll_t v4l2_m2m_poll_for_data(s * If the last buffer was dequeued from the capture queue, * return immediately. DQBUF will return -EPIPE. */ - if (dst_q->last_buffer_dequeued) { - spin_unlock_irqrestore(&dst_q->done_lock, flags); - return EPOLLIN | EPOLLRDNORM; - } + if (dst_q->last_buffer_dequeued) + rc |= EPOLLIN | EPOLLRDNORM; } spin_unlock_irqrestore(&dst_q->done_lock, flags);