diff options
authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2015-02-16 14:38:28 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-04-02 17:29:28 -0300
commit9e68c53910721ffc55c05ee9bbc08129c796b470 (patch)
parentcfa967224382f8ac3adbb40117be776838b91ebc (diff)
[media] uvcvideo: Don't call vb2 mmap and get_unmapped_area with queue lock held
videobuf2 has long been subject to AB-BA style deadlocks due to the queue lock and mmap_sem being taken in different orders for the mmap and get_unmapped_area operations. The problem has been fixed by making those two operations callable without taking the queue lock, using an mmap_lock internal to videobuf2. The uvcvideo driver still calls the mmap and get_unmapped_area operations with the queue lock held, resulting in a potential deadlock. As the operations can now be called without locking the queue, fix it. Reported-by: Bjørn Mork <bjorn@mork.no> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
1 files changed, 2 insertions, 13 deletions
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 10c554e7655c..87a19f33e460 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -306,25 +306,14 @@ int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
- int ret;
- mutex_lock(&queue->mutex);
- ret = vb2_mmap(&queue->queue, vma);
- mutex_unlock(&queue->mutex);
- return ret;
+ return vb2_mmap(&queue->queue, vma);
#ifndef CONFIG_MMU
unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
unsigned long pgoff)
- unsigned long ret;
- mutex_lock(&queue->mutex);
- ret = vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
- mutex_unlock(&queue->mutex);
- return ret;
+ return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);