V4L/DVB: gspca - main: Possible race condition in queue management
The problem may occur with SMP:
- a frame is completed at interrupt level (in gspca_frame_add with
packet_type == LAST_PACKET,
- just after clearing the bit V4L2_BUF_FLAG_QUEUED and before setting
the bit V4L2_BUF_FLAG_DONE, on the other processor, the application
tries to requeue the same frame buffer,
- then, the qbuf function succeeds because ALL_FLAGS are not set.
The fix sets and resets the two flags in one instruction.
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
1 file changed