bttv: Fix a deadlock in the bttv driver

commit 81b2dbcad86732ffc02bad87aa25c4651199fc77 in mainline.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c
index fcf8f2d208a843890df86252ee7579f52cfb385e..594522a155e646dd003cea510901fa1ce7ead970 100644 (file)
--- a/drivers/media/video/bt8xx/bttv-driver.c
+++ b/drivers/media/video/bt8xx/bttv-driver.c
@@ -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);

diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index eab79ffdf56a882529113c0e25623d0c5941ab1c..57a9de4b041cfb7baf28beff67d4f5c210376ea8 100644 (file)
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -335,7 +335,7 @@ 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)
 {
@@ -1093,6 +1093,7 @@ 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);

diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h
index 99033945cdee3790c45240ac0f43a2f61fdec749..755273137609d12356c1a7a3e564ed33b6902795 100644 (file)
--- a/include/media/videobuf-core.h
+++ b/include/media/videobuf-core.h
@@ -227,6 +227,9 @@ 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);