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path: root/drivers/ieee1394/dv1394.c
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Diffstat (limited to 'drivers/ieee1394/dv1394.c')
-rw-r--r--drivers/ieee1394/dv1394.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/ieee1394/dv1394.c b/drivers/ieee1394/dv1394.c
index 965cfdb84ebc..c19f23267157 100644
--- a/drivers/ieee1394/dv1394.c
+++ b/drivers/ieee1394/dv1394.c
@@ -1270,8 +1270,14 @@ static int dv1394_mmap(struct file *file, struct vm_area_struct *vma)
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);