netdev - [PATCH net 6/4] tcp: fix __sk_dst_get usage in tcp_current

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Date:	Fri,  1 Apr 2016 01:56:07 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, sasha.levin@...cle.com,
	daniel@...earbox.net, alexei.starovoitov@...il.com,
	mkubecek@...e.cz
Subject: [PATCH net 6/4] tcp: fix __sk_dst_get usage in tcp_current_mss

Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
 net/ipv4/tcp_output.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ba3621834e7bfa..3f70582578ada0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1426,21 +1426,21 @@ EXPORT_SYMBOL(tcp_sync_mss);
 unsigned int tcp_current_mss(struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
-	const struct dst_entry *dst = __sk_dst_get(sk);
+	const struct dst_entry *dst;
 	u32 mss_now;
 	unsigned int header_len;
 	struct tcp_out_options opts;
 	struct tcp_md5sig_key *md5;
 
+	rcu_read_lock();
 	mss_now = tp->mss_cache;
-
+	dst = __sk_dst_get(sk);
 	if (dst) {
 		u32 mtu = dst_mtu(dst);
 		if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
 			mss_now = tcp_sync_mss(sk, mtu);
 	}
 
-	rcu_read_lock();
 	header_len = tcp_established_options(sk, NULL, &opts, &md5) +
 		     sizeof(struct tcphdr);
 	rcu_read_unlock();
-- 
2.5.5