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udp: Unify buffers for tap and splice paths

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We maintain a set of buffers for UDP packets to be forwarded via the tap
interface in udp[46]_l2_buf.  We then have a separate set of buffers for
packets to be "spliced" in udp_splice_buf[].  However, we only use one of
these at a time, so we can share the buffer space.

For the receiving splice packets we can not only re-use the data buffers
but also the udp[46]_l2_iov_sock and udp[46]_l2_mh_sock control structures.

For sending the splice packets we keep the same data buffers, but we need
specific control structures.  We create udp[46]_iov_splice - we can't
reuse udp_l2_iov_sock[] because we need to write iov_len as we're writing
spliced packets, but the tap path expects iov_len to remain the same (it
only uses it for receive).  Likewise we create udp[46]_mh_splice with the
mmsghdr structures for sending spliced packets.  As well as needing to
reference different iovs, these need to all reference udp_splice_namebuf
instead of individual msg_name fields for each slot.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2022-11-30 15:13:14 +11:00 committed by Stefano Brivio
parent c52ca4aecf
commit fc7f91e709
1 changed files with 32 additions and 41 deletions
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73
udp.c
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@ -219,9 +219,6 @@ struct udp6_l2_buf_t {
#endif #endif
udp6_l2_buf[UDP_MAX_FRAMES]; udp6_l2_buf[UDP_MAX_FRAMES];
static struct sockaddr_storage udp_splice_namebuf;
static uint8_t udp_splice_buf[UDP_MAX_FRAMES][USHRT_MAX];
/* recvmmsg()/sendmmsg() data for tap */ /* recvmmsg()/sendmmsg() data for tap */
static struct iovec udp4_l2_iov_sock [UDP_MAX_FRAMES]; static struct iovec udp4_l2_iov_sock [UDP_MAX_FRAMES];
static struct iovec udp6_l2_iov_sock [UDP_MAX_FRAMES]; static struct iovec udp6_l2_iov_sock [UDP_MAX_FRAMES];
@ -236,11 +233,13 @@ static struct mmsghdr udp4_l2_mh_tap [UDP_MAX_FRAMES];
static struct mmsghdr udp6_l2_mh_tap [UDP_MAX_FRAMES]; static struct mmsghdr udp6_l2_mh_tap [UDP_MAX_FRAMES];
/* recvmmsg()/sendmmsg() data for "spliced" connections */ /* recvmmsg()/sendmmsg() data for "spliced" connections */
static struct iovec udp_iov_recv [UDP_MAX_FRAMES]; static struct sockaddr_storage udp_splice_namebuf;
static struct mmsghdr udp_mmh_recv [UDP_MAX_FRAMES];
static struct iovec udp_iov_sendto [UDP_MAX_FRAMES]; static struct iovec udp4_iov_splice [UDP_MAX_FRAMES];
static struct mmsghdr udp_mmh_sendto [UDP_MAX_FRAMES]; static struct iovec udp6_iov_splice [UDP_MAX_FRAMES];
static struct mmsghdr udp4_mh_splice [UDP_MAX_FRAMES];
static struct mmsghdr udp6_mh_splice [UDP_MAX_FRAMES];
/** /**
* udp_invert_portmap() - Compute reverse port translations for return packets * udp_invert_portmap() - Compute reverse port translations for return packets
@ -522,16 +521,25 @@ static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
{ {
in_port_t src, dst = ref.r.p.udp.udp.port; in_port_t src, dst = ref.r.p.udp.udp.port;
int s, v6 = ref.r.p.udp.udp.v6, n, i; int s, v6 = ref.r.p.udp.udp.v6, n, i;
struct mmsghdr *mmh_recv, *mmh_send;
if (!(events & EPOLLIN)) if (!(events & EPOLLIN))
return; return;
n = recvmmsg(ref.r.s, udp_mmh_recv, UDP_MAX_FRAMES, 0, NULL); if (v6) {
mmh_recv = udp6_l2_mh_sock;
mmh_send = udp6_mh_splice;
} else {
mmh_recv = udp4_l2_mh_sock;
mmh_send = udp4_mh_splice;
}
n = recvmmsg(ref.r.s, mmh_recv, UDP_MAX_FRAMES, 0, NULL);
if (n <= 0) if (n <= 0)
return; return;
src = sa_port(v6, udp_mmh_recv[0].msg_hdr.msg_name); src = sa_port(v6, mmh_recv[0].msg_hdr.msg_name);
if (ref.r.p.udp.udp.ns) { if (ref.r.p.udp.udp.ns) {
src += c->udp.fwd_in.rdelta[src]; src += c->udp.fwd_in.rdelta[src];
@ -562,11 +570,8 @@ static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
udp_splice_ns[v6][src].ts = now->tv_sec; udp_splice_ns[v6][src].ts = now->tv_sec;
} }
for (i = 0; i < n; i++) { for (i = 0; i < n; i++)
struct msghdr *mh_s = &udp_mmh_sendto[i].msg_hdr; mmh_send[i].msg_hdr.msg_iov->iov_len = mmh_recv[i].msg_len;
mh_s->msg_iov->iov_len = udp_mmh_recv[i].msg_len;
}
if (v6) { if (v6) {
*((struct sockaddr_in6 *)&udp_splice_namebuf) = *((struct sockaddr_in6 *)&udp_splice_namebuf) =
@ -586,7 +591,7 @@ static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
}); });
} }
sendmmsg(s, udp_mmh_sendto, n, MSG_NOSIGNAL); sendmmsg(s, mmh_send, n, MSG_NOSIGNAL);
} }
/** /**
@ -1163,37 +1168,23 @@ int udp_sock_init_ns(void *arg)
*/ */
static void udp_splice_iov_init(void) static void udp_splice_iov_init(void)
{ {
struct mmsghdr *h;
struct iovec *iov;
int i; int i;
for (i = 0, h = udp_mmh_recv; i < UDP_MAX_FRAMES; i++, h++) { for (i = 0; i < UDP_MAX_FRAMES; i++) {
struct msghdr *mh = &h->msg_hdr; struct msghdr *mh4 = &udp4_mh_splice[i].msg_hdr;
struct msghdr *mh6 = &udp6_mh_splice[i].msg_hdr;
if (!i) { mh4->msg_name = mh6->msg_name = &udp_splice_namebuf;
mh->msg_name = &udp_splice_namebuf; mh4->msg_namelen = sizeof(udp_splice_namebuf);
mh->msg_namelen = sizeof(udp_splice_namebuf); mh6->msg_namelen = sizeof(udp_splice_namebuf);
}
mh->msg_iov = &udp_iov_recv[i]; udp4_iov_splice[i].iov_base = udp4_l2_buf[i].data;
mh->msg_iovlen = 1; udp6_iov_splice[i].iov_base = udp6_l2_buf[i].data;
mh4->msg_iov = &udp4_iov_splice[i];
mh6->msg_iov = &udp6_iov_splice[i];
mh4->msg_iovlen = mh6->msg_iovlen = 1;
} }
for (i = 0, iov = udp_iov_recv; i < UDP_MAX_FRAMES; i++, iov++) {
iov->iov_base = udp_splice_buf[i];
iov->iov_len = sizeof(udp_splice_buf[i]);
}
for (i = 0, h = udp_mmh_sendto; i < UDP_MAX_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
mh->msg_name = &udp_splice_namebuf;
mh->msg_namelen = sizeof(udp_splice_namebuf);
mh->msg_iov = &udp_iov_sendto[i];
mh->msg_iovlen = 1;
}
for (i = 0, iov = udp_iov_sendto; i < UDP_MAX_FRAMES; i++, iov++)
iov->iov_base = udp_splice_buf[i];
} }
/** /**