[PATCH 09/14] ipv6: hand away dst refs to cork setup
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2022-01-11 01:25:45
Also in:
lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest, user datagram protocol (udp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds, Willem de Bruijn
udpv6_sendmsg() doesn't need dst after calling into ip6_make_skb(), however it still retains a ref and ip6_make_skb() has to do an addition get/put pair. Hand over dst with the reference from ip6_sk_dst_lookup_flow() to avoid two atomics. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- net/ipv6/ip6_output.c | 9 ++++++--- net/ipv6/udp.c | 3 ++- 2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0cc490f2cfbf..6a7bba4dd04d 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c@@ -1356,6 +1356,8 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork, unsigned int mtu; struct ipv6_txoptions *nopt, *opt = ipc6->opt; + cork->base.dst = &rt->dst; + /* * setup for corking */
@@ -1389,8 +1391,6 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork, /* need source address above miyazawa*/ } - dst_hold(&rt->dst); - cork->base.dst = &rt->dst; v6_cork->hop_limit = ipc6->hlimit; v6_cork->tclass = ipc6->tclass; if (rt->dst.flags & DST_XFRM_TUNNEL)
@@ -1784,6 +1784,7 @@ int ip6_append_data(struct sock *sk, /* * setup for corking */ + dst_hold(&rt->dst); err = ip6_setup_cork(sk, &inet->cork, &np->cork, ipc6, rt); if (err)
@@ -1974,8 +1975,10 @@ struct sk_buff *ip6_make_skb(struct sock *sk, int exthdrlen = (ipc6->opt ? ipc6->opt->opt_flen : 0); int err; - if (flags & MSG_PROBE) + if (flags & MSG_PROBE) { + dst_release(&rt->dst); return NULL; + } __skb_queue_head_init(&queue);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index eec83e34ae27..3039dff7fe64 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c@@ -1541,7 +1541,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) err = PTR_ERR(skb); if (!IS_ERR_OR_NULL(skb)) err = udp_v6_send_skb(skb, fl6, &cork.base); - goto out; + /* ip6_make_skb steals dst reference */ + goto out_no_dst; } lock_sock(sk);
--
2.34.1