diff options
| author | Alexandre Courbot <gnurou@gmail.com> | 2020-12-01 13:44:41 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2021-01-04 13:12:46 +0100 |
| commit | 575c52cc4cae8b35654ea2d934d04e649a95cc6f (patch) | |
| tree | 7e0b25d7bd272d90c091b4aa1f5ead15cad4705a | |
| parent | a45c39b8295f39930095f5a3693762f3ea454205 (diff) | |
media: videobuf2: always call poll_wait() on queues
do_poll()/do_select() seem to set the _qproc member of poll_table to
NULL the first time they are called on a given table, making subsequent
calls of poll_wait() on that table no-ops. This is a problem for vb2
which calls poll_wait() on the V4L2 queues' waitqueues only when a
queue-related event is requested, which may not necessarily be the case
during the first poll.
Fix this by making the call to poll_wait() happen first thing and
unconditionally in vb2_core_poll().
Signed-off-by: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
| -rw-r--r-- | drivers/media/common/videobuf2/videobuf2-core.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index 89e38392509c..02281d13505f 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -2374,13 +2374,20 @@ __poll_t vb2_core_poll(struct vb2_queue *q, struct file *file, struct vb2_buffer *vb = NULL; unsigned long flags; + /* + * poll_wait() MUST be called on the first invocation on all the + * potential queues of interest, even if we are not interested in their + * events during this first call. Failure to do so will result in + * queue's events to be ignored because the poll_table won't be capable + * of adding new wait queues thereafter. + */ + poll_wait(file, &q->done_wq, wait); + if (!q->is_output && !(req_events & (EPOLLIN | EPOLLRDNORM))) return 0; if (q->is_output && !(req_events & (EPOLLOUT | EPOLLWRNORM))) return 0; - poll_wait(file, &q->done_wq, wait); - /* * Start file I/O emulator only if streaming API has not been used yet. */ |