tcp: md5: fix rcu lockdep splat

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While timer handler effectively runs a rcu read locked section,
there is no explicit rcu_read_lock()/rcu_read_unlock() annotations
and lockdep can be confused here :

net/ipv4/tcp_ipv4.c-906-        /* caller either holds rcu_read_lock() or socket lock */
net/ipv4/tcp_ipv4.c:907:        md5sig = rcu_dereference_check(tp->md5sig_info,
net/ipv4/tcp_ipv4.c-908-                                       sock_owned_by_user(sk) ||
net/ipv4/tcp_ipv4.c-909-                                       lockdep_is_held(&sk->sk_lock.slock));

Let's explicitely acquire rcu_read_lock() in tcp_make_synack()

Before commit fa76ce7328 ("inet: get rid of central tcp/dccp listener
timer"), we were holding listener lock so lockdep was happy.

Fixes: fa76ce7328 ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric DUmazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Eric Dumazet 2015-03-24 15:58:52 -07:00 • committed by David S. Miller

parent 9ead3527f5

commit 80f03e27a3

1 changed files with 11 additions and 9 deletions

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net/ipv4/tcp_output.c

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