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| author | Maxim Levitsky <maximlevitsky@gmail.com> | 2007-09-27 19:34:09 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@infradead.org> | 2007-10-09 23:02:58 -0400 |
| commit | 9900132f3437e9373aa030cdb5bd2d5db15566e3 (patch) | |
| tree | b4b450daf16d1f502869dd472ae2bad85892daca /drivers/media/video/saa7134/saa7134-video.c | |
| parent | 851c0c96b2212f48fe51afc1589541b5eae3a544 (diff) | |
V4L/DVB (6268): V4L: Fix a lock inversion in generic videobuf code
videobuf_qbuf takes q->lock, and then calls
q->ops->buf_prepare which by design in all drivers calls
videobuf_iolock which calls videobuf_dma_init_user and this
takes current->mm->mmap_sem
on the other hand if user calls mumap from other thread, sys_munmap
takes current->mm->mmap_sem and videobuf_vm_close takes q->lock
Since this can occur only for V4L2_MEMORY_MMAP buffers, take
current->mm->mmap_sem in qbuf, before q->lock, and don't take
current->mm->mmap_sem videobuf_dma_init_user for those buffers
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981
Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'drivers/media/video/saa7134/saa7134-video.c')
0 files changed, 0 insertions, 0 deletions