[RFC,v7,07/14] fixup! vhost: format-independent API for used buffers

Commit Message

Michael S. Tsirkin June 10, 2020, 11:36 a.m. UTC

---
 drivers/vhost/vhost.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

Patch

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index e5763d81bf0f..7a587b13095c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2421,7 +2421,7 @@  int vhost_get_avail_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf,
 err:
 	unfetch_descs(vq);
 
-	return ret ? ret : vq->num;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(vhost_get_avail_buf);
 
@@ -2433,6 +2433,27 @@  void vhost_discard_avail_bufs(struct vhost_virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(vhost_discard_avail_bufs);
 
+/* This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found.  A negative code is
+ * returned on error. */
+int vhost_get_vq_desc(struct vhost_virtqueue *vq,
+		      struct iovec iov[], unsigned int iov_size,
+		      unsigned int *out_num, unsigned int *in_num,
+		      struct vhost_log *log, unsigned int *log_num)
+{
+	struct vhost_buf buf;
+	int ret = vhost_get_avail_buf(vq, &buf,
+				      iov, iov_size, out_num, in_num,
+				      log, log_num);
+
+	if (likely(ret > 0))
+		return buf->id;
+	if (likely(!ret))
+		return vq->num;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
+
 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
 {