linux-kernel - [PATCH 03/10] drm/virtio: fix lock context imbalance

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Message-ID: <1481038106-24899-4-git-send-email-mst@redhat.com>
Date:   Tue, 6 Dec 2016 17:40:42 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jason Wang <jasowang@...hat.com>, David Airlie <airlied@...ux.ie>,
        Gerd Hoffmann <kraxel@...hat.com>,
        dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH 03/10] drm/virtio: fix lock context imbalance

When virtio_gpu_free_vbufs exits due to list empty, it does not
drop the free_vbufs lock that it took.
list empty is not expected to happen anyway, but it can't hurt to fix
this and drop the lock.

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
 drivers/gpu/drm/virtio/virtgpu_vq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 5a0f8a7..2f0c2f9 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -109,8 +109,10 @@ void virtio_gpu_free_vbufs(struct virtio_gpu_device *vgdev)
 
 	spin_lock(&vgdev->free_vbufs_lock);
 	for (i = 0; i < count; i++) {
-		if (WARN_ON(list_empty(&vgdev->free_vbufs)))
+		if (WARN_ON(list_empty(&vgdev->free_vbufs))) {
+			spin_unlock(&vgdev->free_vbufs_lock);
 			return;
+		}
 		vbuf = list_first_entry(&vgdev->free_vbufs,
 					struct virtio_gpu_vbuffer, list);
 		list_del(&vbuf->list);
-- 
MST