struct video_card *video = file_to_video_card(file);
int retval = -EINVAL;
- /* serialize mmap */
- mutex_lock(&video->mtx);
+ /*
+ * We cannot use the blocking variant mutex_lock here because .mmap
+ * is called with mmap_sem held, while .ioctl, .read, .write acquire
+ * video->mtx and subsequently call copy_to/from_user which will
+ * grab mmap_sem in case of a page fault.
+ */
+ if (!mutex_trylock(&video->mtx))
+ return -EAGAIN;
if ( ! video_card_initialized(video) ) {
retval = do_dv1394_init_default(video);
/* OK to free the DMA buffer, no more mappings can exist */
do_dv1394_shutdown(video, 1);
- /* clean up async I/O users */
- dv1394_fasync(-1, file, 0);
-
/* give someone else a turn */
clear_bit(0, &video->open);