netdev - [PATC net-next] tcp: must block bh in __inet_twsk

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Message-ID: <1462320650.5535.334.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Tue, 03 May 2016 17:10:50 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>
Subject: [PATC net-next] tcp: must block bh in __inet_twsk_hashdance()

From: Eric Dumazet <edumazet@...gle.com>

__inet_twsk_hashdance() might be called from process context,
better block BH before acquiring bind hash and established locks

Fixes: c10d9310edf5 ("tcp: do not assume TCP code is non preemptible")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/inet_timewait_sock.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 99ee5c4a9b6844929a995b0b4b5bd693bb211123..2065816748066986f0356df168c2d76fe2d53d85 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -94,7 +94,7 @@ static void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
 }
 
 /*
- * Enter the time wait state. This is called with locally disabled BH.
+ * Enter the time wait state.
  * Essentially we whip up a timewait bucket, copy the relevant info into it
  * from the SK, and mess with hash chains and list linkage.
  */
@@ -112,7 +112,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 	 */
 	bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num,
 			hashinfo->bhash_size)];
-	spin_lock(&bhead->lock);
+	spin_lock_bh(&bhead->lock);
 	tw->tw_tb = icsk->icsk_bind_hash;
 	WARN_ON(!icsk->icsk_bind_hash);
 	inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
@@ -138,7 +138,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 	if (__sk_nulls_del_node_init_rcu(sk))
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 
-	spin_unlock(lock);
+	spin_unlock_bh(lock);
 }
 EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);