drm/virtio: remove incorrect ENOSPC check

The handling of virtqueue_add_sgs ENOSPC error is incorrect because
it can result in out-of-order virtqueue_add_sgs and break fences.
We never get ENOSPC anyway because the caller waits until there is
enough space (the other caller that did not wait was removed in
commit f9c849e4e096 ("drm/virtio: Rewrite virtio_gpu_queue_ctrl_buffer
using fenced version.")).  Remove the incorrect and unnecessary error
path.

This also adds a WARN_ON(ret) until we properly handle errors.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: David Riley <davidriley@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200205181955.202485-3-olvaffe@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 301f47552aeaa37b76f98bf5720816a1445c06b9..2b0a1ea1f7e00f528ac35b28f0fc800bf0818208 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -310,8 +310,6 @@ static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents)
 static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
                                                struct virtio_gpu_vbuffer *vbuf,
                                                struct scatterlist *vout)
-               __releases(&vgdev->ctrlq.qlock)
-               __acquires(&vgdev->ctrlq.qlock)
 {
        struct virtqueue *vq = vgdev->ctrlq.vq;
        struct scatterlist *sgs[3], vcmd, vresp;
@@ -337,19 +335,14 @@ static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
                incnt++;
        }
 
-retry:
        ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC);
-       if (ret == -ENOSPC) {
-               spin_unlock(&vgdev->ctrlq.qlock);
-               wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= outcnt + incnt);
-               spin_lock(&vgdev->ctrlq.qlock);
-               goto retry;
-       } else {
-               trace_virtio_gpu_cmd_queue(vq,
-                       (struct virtio_gpu_ctrl_hdr *)vbuf->buf);
+       WARN_ON(ret);
+
+       trace_virtio_gpu_cmd_queue(vq,
+               (struct virtio_gpu_ctrl_hdr *)vbuf->buf);
+
+       notify = virtqueue_kick_prepare(vq);
 
-               notify = virtqueue_kick_prepare(vq);
-       }
        return notify;
 }