virtio_ring: Add helper to attach vring descriptor

Move the logic for attaching a descriptor to its own function.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a6922ce..d3fc842 100644 (file)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -16,6 +16,18 @@
 #include <linux/bug.h>
 #include <linux/compat.h>
 
+static unsigned int virtqueue_attach_desc(struct virtqueue *vq, unsigned int i,
+                                         struct virtio_sg *sg, u16 flags)
+{
+       struct vring_desc *desc = &vq->vring.desc[i];
+
+       desc->addr = cpu_to_virtio64(vq->vdev, (u64)(uintptr_t)sg->addr);
+       desc->len = cpu_to_virtio32(vq->vdev, sg->length);
+       desc->flags = cpu_to_virtio16(vq->vdev, flags);
+
+       return virtio16_to_cpu(vq->vdev, desc->next);
+}
+
 int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
                  unsigned int out_sgs, unsigned int in_sgs)
 {
@@ -44,27 +56,13 @@ int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
                return -ENOSPC;
        }
 
-       for (n = 0; n < out_sgs; n++) {
-               struct virtio_sg *sg = sgs[n];
-
-               desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
-               desc[i].addr = cpu_to_virtio64(vq->vdev, (u64)(size_t)sg->addr);
-               desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
-
-               prev = i;
-               i = virtio16_to_cpu(vq->vdev, desc[i].next);
-       }
-       for (; n < (out_sgs + in_sgs); n++) {
-               struct virtio_sg *sg = sgs[n];
-
-               desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
-                                               VRING_DESC_F_WRITE);
-               desc[i].addr = cpu_to_virtio64(vq->vdev,
-                                              (u64)(uintptr_t)sg->addr);
-               desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
+       for (n = 0; n < descs_used; n++) {
+               u16 flags = VRING_DESC_F_NEXT;
 
+               if (n >= out_sgs)
+                       flags |= VRING_DESC_F_WRITE;
                prev = i;
-               i = virtio16_to_cpu(vq->vdev, desc[i].next);
+               i = virtqueue_attach_desc(vq, i, sgs[n], flags);
        }
        /* Last one doesn't continue */
        desc[prev].flags &= cpu_to_virtio16(vq->vdev, ~VRING_DESC_F_NEXT);