[media] vb2: fix race condition between REQBUFS and QBUF/PREPARE_BUF

When preparing a buffer the queue lock is released for a short while
if the memory mode is USERPTR (see __buf_prepare for the details), which
would allow a race with a REQBUFS which can free the buffers. Removing the
buffers from underneath __buf_prepare is obviously a bad idea, so we
check if any of the buffers is in the state PREPARING, and if so we
just return -EAGAIN.

If this happens, then the application does something really strange. The
REQBUFS call can be retried safely, since this situation is transient.

Signed-off-by: Hans Verkuil <[email protected]>
Acked-by: Laurent Pinchart <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

0 files changed, 0 insertions, 0 deletions