[PATCH vhost v10 09/10] virtio_ring: introduce virtqueue_add_sg()

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

Introduce virtqueueu_add_sg(), so that in virtio-net we can create an
unify api for rq and sq.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 23 +++++++++++++++++++++++
 include/linux/virtio.h       |  4 ++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 56444f872967..a00f049ea442 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2356,6 +2356,29 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 					out_sgs, in_sgs, data, ctx, gfp);
 }
 
+/**
+ * virtqueue_add_sg - expose buffers to other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: a scatterlist
+ * @num: the number of entries in @sg
+ * @out: whether the sg is readable by other side
+ * @data: the token identifying the buffer.
+ * @ctx: extra context for the token
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_sg(struct virtqueue *vq, struct scatterlist *sg,
+		     unsigned int num, bool out, void *data,
+		     void *ctx, gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, (int)out, (int)!out, data, ctx, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_sg);
+
 /**
  * virtqueue_add_sgs - expose buffers to other end
  * @_vq: the struct virtqueue we're talking about.
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b24f0a665390..1a4aa4382c53 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -55,6 +55,10 @@ struct virtqueue_detach_cursor {
 	unsigned pos:16;
 };
 
+int virtqueue_add_sg(struct virtqueue *vq, struct scatterlist *sg,
+		     unsigned int num, bool out, void *data,
+		     void *ctx, gfp_t gfp);
+
 int virtqueue_add_outbuf(struct virtqueue *vq,
 			 struct scatterlist sg[], unsigned int num,
 			 void *data,
-- 
2.32.0.3.g01195cf9f