Hi,
On 06/09/2014 03:51 PM, Thiago Santos wrote:
> In blocking mode, if there are no buffers available the DQBUF will block
> waiting for a QBUF to be called but it will block holding the streaming
> lock which will prevent any QBUF from happening, causing a deadlock.
>
> Can be tested with: v4l2grab -t -b -s 2000
>
> Signed-off-by: Thiago Santos <ts.santos@xxxxxxxxxxxxxxxx>
Looks good now:
Acked-by: Hans de Goede <hdegoede@xxxxxxxxxx>
I'll leave reviewing the 1st patch to someone else. Gregor and/or
Mauro feel free to push this one.
Regards,
Hans
> ---
> lib/libv4l2/libv4l2-priv.h | 1 +
> lib/libv4l2/libv4l2.c | 13 ++++++++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/lib/libv4l2/libv4l2-priv.h b/lib/libv4l2/libv4l2-priv.h
> index 585273c..ff4c8d2 100644
> --- a/lib/libv4l2/libv4l2-priv.h
> +++ b/lib/libv4l2/libv4l2-priv.h
> @@ -92,6 +92,7 @@ struct v4l2_dev_info {
> unsigned char *frame_pointers[V4L2_MAX_NO_FRAMES];
> int frame_sizes[V4L2_MAX_NO_FRAMES];
> int frame_queued; /* 1 status bit per frame */
> + int frame_info_generation;
> /* mapping tracking of our fake (converting mmap) frame buffers */
> unsigned char frame_map_count[V4L2_MAX_NO_FRAMES];
> /* buffer when doing conversion and using read() for read() */
> diff --git a/lib/libv4l2/libv4l2.c b/lib/libv4l2/libv4l2.c
> index c4d69f7..1dcf34d 100644
> --- a/lib/libv4l2/libv4l2.c
> +++ b/lib/libv4l2/libv4l2.c
> @@ -282,7 +282,7 @@ static int v4l2_dequeue_and_convert(int index, struct v4l2_buffer *buf,
> unsigned char *dest, int dest_size)
> {
> const int max_tries = V4L2_IGNORE_FIRST_FRAME_ERRORS + 1;
> - int result, tries = max_tries;
> + int result, tries = max_tries, frame_info_gen;
>
> /* Make sure we have the real v4l2 buffers mapped */
> result = v4l2_map_buffers(index);
> @@ -290,9 +290,12 @@ static int v4l2_dequeue_and_convert(int index, struct v4l2_buffer *buf,
> return result;
>
> do {
> + frame_info_gen = devices[index].frame_info_generation;
> + pthread_mutex_unlock(&devices[index].stream_lock);
> result = devices[index].dev_ops->ioctl(
> devices[index].dev_ops_priv,
> devices[index].fd, VIDIOC_DQBUF, buf);
> + pthread_mutex_lock(&devices[index].stream_lock);
> if (result) {
> if (errno != EAGAIN) {
> int saved_err = errno;
> @@ -305,6 +308,11 @@ static int v4l2_dequeue_and_convert(int index, struct v4l2_buffer *buf,
>
> devices[index].frame_queued &= ~(1 << buf->index);
>
> + if (frame_info_gen != devices[index].frame_info_generation) {
> + errno = -EINVAL;
> + return -1;
> + }
> +
> result = v4lconvert_convert(devices[index].convert,
> &devices[index].src_fmt, &devices[index].dest_fmt,
> devices[index].frame_pointers[buf->index],
> @@ -839,6 +847,7 @@ int v4l2_dup(int fd)
>
> static int v4l2_check_buffer_change_ok(int index)
> {
> + devices[index].frame_info_generation++;
> v4l2_unmap_buffers(index);
>
> /* Check if the app itself still is using the stream */
> @@ -1294,9 +1303,11 @@ no_capture_request:
> }
>
> if (!v4l2_needs_conversion(index)) {
> + pthread_mutex_unlock(&devices[index].stream_lock);
> result = devices[index].dev_ops->ioctl(
> devices[index].dev_ops_priv,
> fd, VIDIOC_DQBUF, buf);
> + pthread_mutex_lock(&devices[index].stream_lock);
> if (result) {
> saved_err = errno;
> V4L2_PERROR("dequeuing buf");
>
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