[RFC PATCH net-next 01/12] vhost_net: introduce helper to initialize tx iov iter

[Jason Wang]

Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/vhost/net.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index c4b49fc..15d191a 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -459,6 +459,26 @@ static bool vhost_exceeds_maxpend(struct vhost_net *net)
               min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 }
 
+static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
+                           size_t hdr_size, int out)
+{
+       /* Skip header. TODO: support TSO. */
+       size_t len = iov_length(vq->iov, out);
+
+       iov_iter_init(iter, WRITE, vq->iov, out, len);
+       iov_iter_advance(iter, hdr_size);
+       /* Sanity check */
+       if (!iov_iter_count(iter)) {
+               vq_err(vq, "Unexpected header len for TX: "
+                       "%zd expected %zd\n",
+                       len, hdr_size);
+               return -EFAULT;
+       }
+       len = iov_iter_count(iter);
+
+       return len;
+}
+
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
 static void handle_tx(struct vhost_net *net)
@@ -521,18 +541,10 @@ static void handle_tx(struct vhost_net *net)
                               "out %d, int %d\n", out, in);
                        break;
                }
-               /* Skip header. TODO: support TSO. */
-               len = iov_length(vq->iov, out);
-               iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
-               iov_iter_advance(&msg.msg_iter, hdr_size);
-               /* Sanity check */
-               if (!msg_data_left(&msg)) {
-                       vq_err(vq, "Unexpected header len for TX: "
-                              "%zd expected %zd\n",
-                              len, hdr_size);
+
+               len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out);
+               if (len < 0)
                        break;
-               }
-               len = msg_data_left(&msg);
 
                zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
                                   && !vhost_exceeds_maxpend(net)
-- 
2.7.4