Hi Antti, Is this still needed after this commit was merged? http://git.linuxtv.org/media_tree.git/commit/b18a8ff29d80b132018d33479e86ab8ecaee6b46 Regards, Hans On 12/29/2013 05:51 AM, Antti Palosaari wrote: > Avoid that lockdep warning: > > [ INFO: possible circular locking dependency detected ] > 3.13.0-rc1+ #77 Tainted: G C O > ------------------------------------------------------- > video_source:sr/32072 is trying to acquire lock: > (&dev->mutex#2){+.+.+.}, at: [<ffffffffa073fde3>] vb2_fop_mmap+0x33/0x90 [videobuf2_core] > > but task is already holding lock: > (&mm->mmap_sem){++++++}, at: [<ffffffff8117825f>] vm_mmap_pgoff+0x6f/0xc0 > > Possible unsafe locking scenario: > CPU0 CPU1 > ---- ---- > lock(&mm->mmap_sem); > lock(&dev->mutex#2); > lock(&mm->mmap_sem); > lock(&dev->mutex#2); > *** DEADLOCK *** > > Signed-off-by: Antti Palosaari <crope@xxxxxx> > --- > drivers/media/v4l2-core/videobuf2-core.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 12df9fd..2a74295 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -2641,12 +2641,24 @@ int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) > struct video_device *vdev = video_devdata(file); > struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock; > int err; > + /* > + * FIXME: Ugly hack. Disable possible lockdep as it detects possible > + * deadlock. "INFO: possible circular locking dependency detected" > + */ > + lockdep_off(); > > - if (lock && mutex_lock_interruptible(lock)) > + if (lock && mutex_lock_interruptible(lock)) { > + lockdep_on(); > return -ERESTARTSYS; > + } > + > err = vb2_mmap(vdev->queue, vma); > + > if (lock) > mutex_unlock(lock); > + > + lockdep_on(); > + > return err; > } > EXPORT_SYMBOL_GPL(vb2_fop_mmap); > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
