udp_vu_sock_recv() currently mixes two concerns: receiving data from the
socket and managing virtqueue buffers (collecting, rewinding, releasing).
This makes the function harder to reason about and couples socket I/O
with virtqueue state.
Move all virtqueue operations, vu_collect(), vu_init_elem(),
vu_queue_rewind(), vu_set_vnethdr(), and the queue-readiness check, into
udp_vu_sock_to_tap(), which is the only caller. This turns
udp_vu_sock_recv() into a pure socket receive function that simply reads
into the provided iov array and adjusts its length.
Signed-off-by: Laurent Vivier
---
udp_vu.c | 97 ++++++++++++++++++++++++++++----------------------------
1 file changed, 49 insertions(+), 48 deletions(-)
diff --git a/udp_vu.c b/udp_vu.c
index f8629af58ab5..34f39e1256f8 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -58,46 +58,22 @@ static size_t udp_vu_hdrlen(bool v6)
/**
* udp_vu_sock_recv() - Receive datagrams from socket into vhost-user buffers
- * @c: Execution context
- * @vq: virtqueue to use to receive data
* @s: Socket to receive from
* @v6: Set for IPv6 connections
- * @dlen: Size of received data (output)
+ * @iov_cnt: Number of collected iov in iov_vu (input)
+ * Number of iov entries used to store the datagram (output)
*
- * Return: number of iov entries used to store the datagram, 0 if the datagram
- * was discarded because the virtqueue is not ready, -1 on error
+ * Return: size of received data, -1 on error
*/
-static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
- bool v6, ssize_t *dlen)
+static ssize_t udp_vu_sock_recv(int s, bool v6, size_t *iov_cnt)
{
- const struct vu_dev *vdev = c->vdev;
- int elem_cnt, elem_used, iov_used;
struct msghdr msg = { 0 };
size_t hdrlen, l2len;
- size_t iov_cnt;
-
- assert(!c->no_udp);
-
- if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
- debug("Got UDP packet, but RX virtqueue not usable yet");
-
- if (recvmsg(s, &msg, MSG_DONTWAIT) < 0)
- debug_perror("Failed to discard datagram");
-
- return 0;
- }
+ ssize_t dlen;
/* compute L2 header length */
hdrlen = udp_vu_hdrlen(v6);
- elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem),
- iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt,
- IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL);
- if (elem_cnt == 0)
- return -1;
-
- assert((size_t)elem_cnt == iov_cnt); /* one iovec per element */
-
/* reserve space for the headers */
assert(iov_vu[0].iov_len >= MAX(hdrlen, ETH_ZLEN + VNET_HLEN));
iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen;
@@ -105,29 +81,23 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
/* read data from the socket */
msg.msg_iov = iov_vu;
- msg.msg_iovlen = iov_cnt;
+ msg.msg_iovlen = *iov_cnt;
- *dlen = recvmsg(s, &msg, 0);
- if (*dlen < 0) {
- vu_queue_rewind(vq, elem_cnt);
+ dlen = recvmsg(s, &msg, 0);
+ if (dlen < 0)
return -1;
- }
/* restore the pointer to the headers address */
iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen;
iov_vu[0].iov_len += hdrlen;
- iov_used = iov_truncate(iov_vu, iov_cnt, *dlen + hdrlen);
- elem_used = iov_used; /* one iovec per element */
+ *iov_cnt = iov_truncate(iov_vu, *iov_cnt, dlen + hdrlen);
/* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */
- l2len = *dlen + hdrlen - VNET_HLEN;
+ l2len = dlen + hdrlen - VNET_HLEN;
vu_pad(&iov_vu[0], l2len);
- /* release unused buffers */
- vu_queue_rewind(vq, elem_cnt - elem_used);
-
- return iov_used;
+ return dlen;
}
/**
@@ -213,21 +183,52 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx)
struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
int i;
+ assert(!c->no_udp);
+
+ if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+ struct msghdr msg = { 0 };
+
+ debug("Got UDP packet, but RX virtqueue not usable yet");
+
+ for (i = 0; i < n; i++) {
+ if (recvmsg(s, &msg, MSG_DONTWAIT) < 0)
+ debug_perror("Failed to discard datagram");
+ }
+
+ return;
+ }
+
for (i = 0; i < n; i++) {
+ unsigned elem_cnt, elem_used;
+ size_t iov_cnt;
ssize_t dlen;
- int iov_used;
- iov_used = udp_vu_sock_recv(c, vq, s, v6, &dlen);
- if (iov_used < 0)
+ elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem),
+ iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt,
+ IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL);
+ if (elem_cnt == 0)
+ break;
+
+ assert((size_t)elem_cnt == iov_cnt); /* one iovec per element */
+
+ dlen = udp_vu_sock_recv(s, v6, &iov_cnt);
+ if (dlen < 0) {
+ vu_queue_rewind(vq, iov_cnt);
break;
+ }
+
+ elem_used = iov_cnt; /* one iovec per element */
+
+ /* release unused buffers */
+ vu_queue_rewind(vq, elem_cnt - elem_used);
- if (iov_used > 0) {
+ if (iov_cnt > 0) {
udp_vu_prepare(c, toside, dlen);
if (*c->pcap) {
- udp_vu_csum(toside, iov_used);
- pcap_iov(iov_vu, iov_used, VNET_HLEN);
+ udp_vu_csum(toside, iov_cnt);
+ pcap_iov(iov_vu, iov_cnt, VNET_HLEN);
}
- vu_flush(vdev, vq, elem, iov_used);
+ vu_flush(vdev, vq, elem, iov_cnt);
vu_queue_notify(vdev, vq);
}
}
--
2.53.0