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

Jason Wang
2018-05-21T09:04:56Z

Signed-off-by: Jason Wang <jasowang@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