drm/virtio: set up virtqueue sgs before locking

sgs setup does not need to be in the critical section.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200205181955.202485-7-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 0ceceb3..c8baa68 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -318,34 +318,19 @@ static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents)
        return sgt;
 }
 
-static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
-                                               struct virtio_gpu_vbuffer *vbuf,
-                                               struct scatterlist *vout)
+static bool virtio_gpu_queue_ctrl_sgs_locked(struct virtio_gpu_device *vgdev,
+                                            struct virtio_gpu_vbuffer *vbuf,
+                                            struct scatterlist **sgs,
+                                            int outcnt,
+                                            int incnt)
 {
        struct virtqueue *vq = vgdev->ctrlq.vq;
-       struct scatterlist *sgs[3], vcmd, vresp;
-       int outcnt = 0, incnt = 0;
        bool notify = false;
        int ret;
 
        if (!vgdev->vqs_ready)
                return notify;
 
-       sg_init_one(&vcmd, vbuf->buf, vbuf->size);
-       sgs[outcnt + incnt] = &vcmd;
-       outcnt++;
-
-       if (vout) {
-               sgs[outcnt + incnt] = vout;
-               outcnt++;
-       }
-
-       if (vbuf->resp_size) {
-               sg_init_one(&vresp, vbuf->resp_buf, vbuf->resp_size);
-               sgs[outcnt + incnt] = &vresp;
-               incnt++;
-       }
-
        ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC);
        WARN_ON(ret);
 
@@ -361,26 +346,45 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
                                                struct virtio_gpu_fence *fence)
 {
        struct virtqueue *vq = vgdev->ctrlq.vq;
-       struct scatterlist *vout = NULL, sg;
+       struct scatterlist *sgs[3], vcmd, vout, vresp;
        struct sg_table *sgt = NULL;
+       int elemcnt = 0, outcnt = 0, incnt = 0;
        bool notify;
-       int outcnt = 0;
 
+       /* set up vcmd */
+       sg_init_one(&vcmd, vbuf->buf, vbuf->size);
+       elemcnt++;
+       sgs[outcnt] = &vcmd;
+       outcnt++;
+
+       /* set up vout */
        if (vbuf->data_size) {
                if (is_vmalloc_addr(vbuf->data_buf)) {
+                       int sg_ents;
                        sgt = vmalloc_to_sgt(vbuf->data_buf, vbuf->data_size,
-                                            &outcnt);
+                                            &sg_ents);
                        if (!sgt) {
                                if (fence && vbuf->objs)
                                        virtio_gpu_array_unlock_resv(vbuf->objs);
                                return;
                        }
-                       vout = sgt->sgl;
+
+                       elemcnt += sg_ents;
+                       sgs[outcnt] = sgt->sgl;
                } else {
-                       sg_init_one(&sg, vbuf->data_buf, vbuf->data_size);
-                       vout = &sg;
-                       outcnt = 1;
+                       sg_init_one(&vout, vbuf->data_buf, vbuf->data_size);
+                       elemcnt++;
+                       sgs[outcnt] = &vout;
                }
+               outcnt++;
+       }
+
+       /* set up vresp */
+       if (vbuf->resp_size) {
+               sg_init_one(&vresp, vbuf->resp_buf, vbuf->resp_size);
+               elemcnt++;
+               sgs[outcnt + incnt] = &vresp;
+               incnt++;
        }
 
 again:
@@ -394,10 +398,9 @@ again:
         * to wait for free space, which can result in fence ids being
         * submitted out-of-order.
         */
-       if (vq->num_free < 2 + outcnt) {
+       if (vq->num_free < elemcnt) {
                spin_unlock(&vgdev->ctrlq.qlock);
-               wait_event(vgdev->ctrlq.ack_queue,
-                          vq->num_free >= 2 + outcnt);
+               wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= elemcnt);
                goto again;
        }
 
@@ -409,7 +412,8 @@ again:
                        virtio_gpu_array_unlock_resv(vbuf->objs);
                }
        }
-       notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf, vout);
+       notify = virtio_gpu_queue_ctrl_sgs_locked(vgdev, vbuf, sgs, outcnt,
+                                                 incnt);
        spin_unlock(&vgdev->ctrlq.qlock);
        if (notify) {
                if (vgdev->disable_notify)