From: Maxim Levitsky Date: Thu, 27 Sep 2007 23:34:09 +0000 (-0300) Subject: V4L/DVB (6268): V4L: Fix a lock inversion in generic videobuf code X-Git-Tag: v2.6.24-rc1~1463^2~37 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9900132f3437e9373aa030cdb5bd2d5db15566e3;p=pandora-kernel.git 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 http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981 Reviewed-by: Ricardo Cerqueira Signed-off-by: Mauro Carvalho Chehab --- Reading git-diff-tree failed