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

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Message-ID: <c774b30d-273c-486f-380d-571ed49882cf@redhat.com>
Date:   Wed, 7 Dec 2016 12:13:40 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>, linux-kernel@...r.kernel.org
Cc:     David Airlie <airlied@...ux.ie>, Gerd Hoffmann <kraxel@...hat.com>,
        dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 03/10] drm/virtio: fix lock context imbalance



On 2016年12月06日 23:40, Michael S. Tsirkin wrote:
> 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(-)

Reviewed-by: Jason Wang <jasowang@...hat.com>

>
> 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);