netdev - [PATCH net-next 27/27] ipv6: clean up ip6_setup

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Date:   Sun,  3 Apr 2022 14:06:39 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Eric Dumazet <edumazet@...gle.com>, Wei Liu <wei.liu@...nel.org>,
        Paul Durrant <paul@....org>,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [PATCH net-next 27/27] ipv6: clean up ip6_setup_cork

Do a bit of refactoring for ip6_setup_cork(). Cache a xfrm_dst_path()
result to not call it twice, reshuffle ifs to not repeat some parts
twice and so.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 net/ipv6/ip6_output.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f7c092af64f5..e10b7f42e493 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1356,15 +1356,13 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	unsigned int mtu;
 	struct ipv6_txoptions *nopt, *opt = ipc6->opt;
+	struct dst_entry *xrfm_dst;
 
 	/* callers pass dst together with a reference, set it first so
 	 * ip6_cork_release() can put it down even in case of an error.
 	 */
 	cork->base.dst = &rt->dst;
 
-	/*
-	 * setup for corking
-	 */
 	if (opt) {
 		if (WARN_ON(v6_cork->opt))
 			return -EINVAL;
@@ -1397,28 +1395,26 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 	}
 	v6_cork->hop_limit = ipc6->hlimit;
 	v6_cork->tclass = ipc6->tclass;
-	if (rt->dst.flags & DST_XFRM_TUNNEL)
-		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
-		      READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst);
+
+	xrfm_dst = xfrm_dst_path(&rt->dst);
+	if (dst_allfrag(xrfm_dst))
+		cork->base.flags |= IPCORK_ALLFRAG;
+
+	if (np->pmtudisc < IPV6_PMTUDISC_PROBE)
+		mtu = dst_mtu(rt->dst.flags & DST_XFRM_TUNNEL ? &rt->dst : xrfm_dst);
 	else
-		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
-			READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst));
-	if (np->frag_size < mtu) {
-		if (np->frag_size)
-			mtu = np->frag_size;
-	}
+		mtu = READ_ONCE(rt->dst.dev->mtu);
+
+	if (np->frag_size < mtu && np->frag_size)
+		mtu = np->frag_size;
+
 	cork->base.fragsize = mtu;
 	cork->base.gso_size = ipc6->gso_size;
 	cork->base.tx_flags = 0;
 	cork->base.mark = ipc6->sockc.mark;
 	sock_tx_timestamp(sk, ipc6->sockc.tsflags, &cork->base.tx_flags);
-
-	if (dst_allfrag(xfrm_dst_path(&rt->dst)))
-		cork->base.flags |= IPCORK_ALLFRAG;
 	cork->base.length = 0;
-
 	cork->base.transmit_time = ipc6->sockc.transmit_time;
-
 	return 0;
 }
 
-- 
2.35.1