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Commit 81b2dbca authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Linus Torvalds
Browse files

Fix a deadlock in the bttv driver 



vidiocgmbuf() does this:
        mutex_lock(&fh->cap.vb_lock);
        retval = videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize,
                                     V4L2_MEMORY_MMAP);

and videobuf_mmap_setup() then just does
        mutex_lock(&q->vb_lock);
        ret = __videobuf_mmap_setup(q, bcount, bsize, memory);
        mutex_unlock(&q->vb_lock);

which is an obvious double-take deadlock.

This patch fixes this by having vidiocgmbuf() just call the
__videobuf_mmap_setup function instead.

Acked-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
Reported-by: default avatarKoos Vriezen <koos.vriezen@gmail.com>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent babd90b2

drivers/media/video/bt8xx/bttv-driver.c

+1 −1
Original line number Diff line number Diff line
@@ -2613,7 +2613,7 @@ static int vidiocgmbuf(struct file *file, void *priv, struct video_mbuf *mbuf) 
	struct bttv_fh *fh = priv;



	mutex_lock(&fh->cap.vb_lock);

	retval = videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize,

	retval = __videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize,

				     V4L2_MEMORY_MMAP);

	if (retval < 0) {

		mutex_unlock(&fh->cap.vb_lock);

drivers/media/video/videobuf-core.c

+2 −1
Original line number Diff line number Diff line
@@ -331,7 +331,7 @@ int videobuf_mmap_free(struct videobuf_queue *q) 
}



/* Locking: Caller holds q->vb_lock */

static int __videobuf_mmap_setup(struct videobuf_queue *q,

int __videobuf_mmap_setup(struct videobuf_queue *q,

			unsigned int bcount, unsigned int bsize,

			enum v4l2_memory memory)

{
@@ -1129,6 +1129,7 @@ EXPORT_SYMBOL_GPL(videobuf_read_stream); 
EXPORT_SYMBOL_GPL(videobuf_read_one);

EXPORT_SYMBOL_GPL(videobuf_poll_stream);



EXPORT_SYMBOL_GPL(__videobuf_mmap_setup);

EXPORT_SYMBOL_GPL(videobuf_mmap_setup);

EXPORT_SYMBOL_GPL(videobuf_mmap_free);

EXPORT_SYMBOL_GPL(videobuf_mmap_mapper);

include/media/videobuf-core.h

+3 −0
Original line number Diff line number Diff line
@@ -237,6 +237,9 @@ unsigned int videobuf_poll_stream(struct file *file, 
int videobuf_mmap_setup(struct videobuf_queue *q,

			unsigned int bcount, unsigned int bsize,

			enum v4l2_memory memory);

int __videobuf_mmap_setup(struct videobuf_queue *q,

			unsigned int bcount, unsigned int bsize,

			enum v4l2_memory memory);

int videobuf_mmap_free(struct videobuf_queue *q);

int videobuf_mmap_mapper(struct videobuf_queue *q,

			 struct vm_area_struct *vma);