When we receive datagrams on a socket, we need to split them into batches
depending on how they need to be forwarded (either via a specific splice
socket, or via tap). The logic to do this, is somewhat awkwardly split
between udp_buf_sock_handler() itself, udp_splice_send() and
udp_tap_send().
Move all the batching logic into udp_buf_sock_handler(), leaving
udp_splice_send() to just send the prepared batch. udp_tap_send() reduces
to just a call to tap_send_frames() so open-code that call in
udp_buf_sock_handler().
This will allow separating the batching logic from the rest of the datagram
forwarding logic, which we'll need for upcoming flow table support.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
udp.c | 132 +++++++++++++++++++---------------------------------------
1 file changed, 42 insertions(+), 90 deletions(-)
diff --git a/udp.c b/udp.c
index af5f23f0..dee402f7 100644
--- a/udp.c
+++ b/udp.c
@@ -501,42 +501,29 @@ static void udp_splice_prepare(struct mmsghdr *mmh, unsigned idx)
}
/**
- * udp_splice_send() - Send datagrams from socket to socket
+ * udp_splice_send() - Send a batch of datagrams from socket to socket
* @c: Execution context
- * @start: Index of first datagram in udp[46]_l2_buf
- * @n: Total number of datagrams in udp[46]_l2_buf pool
- * @dst: Datagrams will be sent to this port (on destination side)
+ * @start: Index of batch's first datagram in udp[46]_l2_buf
+ * @n: Number of datagrams in batch
+ * @src: Source port for datagram (target side)
+ * @dst: Destination port for datagrams (target side)
* @ref: epoll reference for origin socket
* @now: Timestamp
- *
- * This consumes as many datagrams as are sendable via a single socket. It
- * requires that udp_meta[(a)start].splicesrc is initialised, and will initialise
- * udp_meta[].splicesrc for each datagram it consumes *and one more* (if
- * present).
- *
- * Return: Number of datagrams forwarded
*/
-static unsigned udp_splice_send(const struct ctx *c, size_t start, size_t n,
- in_port_t dst, union epoll_ref ref,
- const struct timespec *now)
+static void udp_splice_send(const struct ctx *c, size_t start, size_t n,
+ in_port_t src, in_port_t dst,
+ union epoll_ref ref,
+ const struct timespec *now)
{
- in_port_t src = udp_meta[start].splicesrc;
- struct mmsghdr *mmh_recv;
- unsigned int i = start;
int s;
- ASSERT(udp_meta[start].splicesrc >= 0);
- ASSERT(ref.type == EPOLL_TYPE_UDP);
-
if (ref.udp.v6) {
- mmh_recv = udp6_mh_recv;
udp_splice_to.sa6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_addr = in6addr_loopback,
.sin6_port = htons(dst),
};
} else {
- mmh_recv = udp4_mh_recv;
udp_splice_to.sa4 = (struct sockaddr_in) {
.sin_family = AF_INET,
.sin_addr = in4addr_loopback,
@@ -544,15 +531,6 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start,
size_t n,
};
}
- do {
- udp_splice_prepare(mmh_recv, i);
-
- if (++i >= n)
- break;
-
- udp_meta[i].splicesrc = udp_mmh_splice_port(ref, &mmh_recv[i]);
- } while (udp_meta[i].splicesrc == src);
-
if (ref.udp.pif == PIF_SPLICE) {
src += c->udp.fwd_in.rdelta[src];
s = udp_splice_init[ref.udp.v6][src].sock;
@@ -560,7 +538,7 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start,
size_t n,
s = udp_splice_new(c, ref.udp.v6, src, false);
if (s < 0)
- goto out;
+ return;
udp_splice_ns[ref.udp.v6][dst].ts = now->tv_sec;
udp_splice_init[ref.udp.v6][src].ts = now->tv_sec;
@@ -577,15 +555,13 @@ static unsigned udp_splice_send(const struct ctx *c, size_t start,
size_t n,
s = arg.s;
}
if (s < 0)
- goto out;
+ return;
udp_splice_init[ref.udp.v6][dst].ts = now->tv_sec;
udp_splice_ns[ref.udp.v6][src].ts = now->tv_sec;
}
- sendmmsg(s, udp_mh_splice + start, i - start, MSG_NOSIGNAL);
-out:
- return i - start;
+ sendmmsg(s, udp_mh_splice + start, n, MSG_NOSIGNAL);
}
/**
@@ -725,7 +701,7 @@ static size_t udp_update_hdr6(const struct ctx *c,
* @v6: Prepare for IPv6?
* @now: Current timestamp
*/
-static void udp_tap_prepare(const struct ctx *c, struct mmsghdr *mmh,
+static void udp_tap_prepare(const struct ctx *c, const struct mmsghdr *mmh,
unsigned idx, in_port_t dstport, bool v6,
const struct timespec *now)
{
@@ -752,49 +728,6 @@ static void udp_tap_prepare(const struct ctx *c, struct mmsghdr
*mmh,
(*tap_iov)[UDP_IOV_PAYLOAD].iov_len = l4len;
}
-/**
- * udp_tap_send() - Prepare UDP datagrams and send to tap interface
- * @c: Execution context
- * @start: Index of first datagram in udp[46]_l2_buf pool
- * @n: Total number of datagrams in udp[46]_l2_buf pool
- * @dstport: Destination port number on destination side
- * @ref: epoll reference for origin socket
- * @now: Current timestamp
- *
- * This consumes as many frames as are sendable via tap. It requires that
- * udp_meta[(a)start].splicesrc is initialised, and will initialise
- * udp_meta[].splicesrc for each frame it consumes *and one more* (if present).
- *
- * Return: Number of frames sent via tap
- */
-static unsigned udp_tap_send(const struct ctx *c, size_t start, size_t n,
- in_port_t dstport, union epoll_ref ref,
- const struct timespec *now)
-{
- struct mmsghdr *mmh_recv;
- size_t i = start;
-
- ASSERT(udp_meta[start].splicesrc == -1);
- ASSERT(ref.type == EPOLL_TYPE_UDP);
-
- if (ref.udp.v6)
- mmh_recv = udp6_mh_recv;
- else
- mmh_recv = udp4_mh_recv;
-
- do {
- udp_tap_prepare(c, mmh_recv, i, dstport, ref.udp.v6, now);
-
- if (++i >= n)
- break;
-
- udp_meta[i].splicesrc = udp_mmh_splice_port(ref, &mmh_recv[i]);
- } while (udp_meta[i].splicesrc == -1);
-
- tap_send_frames(c, &udp_l2_iov[start][0], UDP_NUM_IOVS, i - start);
- return i - start;
-}
-
/**
* udp_sock_recv() - Receive datagrams from a socket
* @c: Execution context
@@ -842,7 +775,7 @@ void udp_buf_sock_handler(const struct ctx *c, union epoll_ref ref,
uint32_t eve
{
struct mmsghdr *mmh_recv = ref.udp.v6 ? udp6_mh_recv : udp4_mh_recv;
in_port_t dstport = ref.udp.port;
- int n, m, i;
+ int n, i;
if ((n = udp_sock_recv(c, ref.fd, events, mmh_recv)) <= 0)
return;
@@ -852,19 +785,38 @@ void udp_buf_sock_handler(const struct ctx *c, union epoll_ref ref,
uint32_t eve
else if (ref.udp.pif == PIF_HOST)
dstport += c->udp.fwd_in.f.delta[dstport];
- /* We divide things into batches based on how we need to send them,
+ /* We divide datagrams into batches based on how we need to send them,
* determined by udp_meta[i].splicesrc. To avoid either two passes
* through the array, or recalculating splicesrc for a single entry, we
- * have to populate it one entry *ahead* of the loop counter (if
- * present). So we fill in entry 0 before the loop, then udp_*_send()
- * populate one entry past where they consume.
+ * have to populate it one entry *ahead* of the loop counter.
*/
udp_meta[0].splicesrc = udp_mmh_splice_port(ref, mmh_recv);
- for (i = 0; i < n; i += m) {
- if (udp_meta[i].splicesrc >= 0)
- m = udp_splice_send(c, i, n, dstport, ref, now);
- else
- m = udp_tap_send(c, i, n, dstport, ref, now);
+ for (i = 0; i < n; ) {
+ int batchsrc = udp_meta[i].splicesrc;
+ int batchstart = i;
+
+ do {
+ if (batchsrc >= 0) {
+ udp_splice_prepare(mmh_recv, i);
+ } else {
+ udp_tap_prepare(c, mmh_recv, i, dstport,
+ ref.udp.v6, now);
+ }
+
+ if (++i >= n)
+ break;
+
+ udp_meta[i].splicesrc = udp_mmh_splice_port(ref,
+ &mmh_recv[i]);
+ } while (udp_meta[i].splicesrc == batchsrc);
+
+ if (batchsrc >= 0) {
+ udp_splice_send(c, batchstart, i - batchstart,
+ batchsrc, dstport, ref, now);
+ } else {
+ tap_send_frames(c, &udp_l2_iov[batchstart][0],
+ UDP_NUM_IOVS, i - batchstart);
+ }
}
}
--
2.45.2