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Fix a deadlock in the bttv driver

Browse source 
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: Mauro Carvalho Chehab <mchehab@infradead.org>
Reported-by: Koos Vriezen <koos.vriezen@gmail.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arjan van de Ven 2008-05-20 09:53:52 -07:00 committed by Linus Torvalds
parent babd90b274
commit 81b2dbcad8
3 changed files with 6 additions and 2 deletions
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2
drivers/media/video/bt8xx/bttv-driver.c
View file

@ -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);

3
drivers/media/video/videobuf-core.c
View file

@ -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);

3
include/media/videobuf-core.h
View file

@ -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);