Commit da0dd507 authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
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media: atomisp: Fix deadlock when the /dev/video# node is closed while still streaming 



atomisp_release() was taking pipe->vb_queue_mutex + isp->mutex at the
same time. But if the /dev/video# node is closed while still streaming
then vb2_queue_release() will call atomisp_stop_streaming() which takes
isp->mutex itself, leading to a deadlock.

To fix this only take isp->mutex after cleaning up the v4l2_fh /
the vb2_queue. While at it switch to vb2_fop_release() which will take
pipe->vb_queue_mutex for us, which also resolves a FIXME comment.

Reviewed-by: default avatarAndy Shevchenko <andy@kernel.org>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent ac8dd062

drivers/staging/media/atomisp/pci/atomisp_fops.c

+5 −16
Original line number Diff line number Diff line
@@ -860,23 +860,14 @@ static int atomisp_release(struct file *file) 


	v4l2_fh_init(&fh.vfh, vdev);



	mutex_lock(&pipe->vb_queue_mutex);

	mutex_lock(&isp->mutex);



	dev_dbg(isp->dev, "release device %s\n", vdev->name);



	asd->subdev.devnode = vdev;



	/*

	 * FIXME This if is copied from _vb2_fop_release, this cannot use that

	 * because that calls v4l2_fh_release() earlier then this function.

	 * Maybe we can release the fh earlier though, it does not look like

	 * anything needs it after this.

	 */

	if (file->private_data == vdev->queue->owner) {

		vb2_queue_release(vdev->queue);

		vdev->queue->owner = NULL;

	}

	/* Note file must not be used after this! */

	vb2_fop_release(file);



	mutex_lock(&isp->mutex);



	pipe->users--;

	if (pipe->users)
@@ -939,9 +930,7 @@ static int atomisp_release(struct file *file) 
				     V4L2_SEL_TGT_COMPOSE, 0,

				     &clear_compose);

	mutex_unlock(&isp->mutex);

	mutex_unlock(&pipe->vb_queue_mutex);



	return v4l2_fh_release(file);

	return 0;

}



const struct v4l2_file_operations atomisp_fops = {