On Thu, 27 Aug 2020 at 09:50, Alexandre Courbot <[email protected]> wrote: > > 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 <[email protected]>
Reviewed-by: Ezequiel Garcia <[email protected]> > --- > drivers/media/v4l2-core/v4l2-mem2mem.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c > b/drivers/media/v4l2-core/v4l2-mem2mem.c > index 95a8f2dc5341d..fe90c3c0e4128 100644 > --- a/drivers/media/v4l2-core/v4l2-mem2mem.c > +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c > @@ -868,10 +868,8 @@ static __poll_t v4l2_m2m_poll_for_data(struct file *file, > * 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); > > -- > 2.28.0 >
