dst: rcu check refinement
__sk_dst_get() might be called from softirq, with socket lock held.
[ 159.026180] include/net/sock.h:1200 invoked rcu_dereference_check()
without protection!
[ 159.026261]
[ 159.026261] other info that might help us debug this:
[ 159.026263]
[ 159.026425]
[ 159.026426] rcu_scheduler_active = 1, debug_locks = 0
[ 159.026552] 2 locks held by swapper/0:
[ 159.026609] #0: (&icsk->icsk_retransmit_timer){+.-...}, at:
[<ffffffff8104fc15>] run_timer_softirq+0x105/0x350
[ 159.026839] #1: (slock-AF_INET){+.-...}, at: [<ffffffff81392b8f>]
tcp_write_timer+0x2f/0x1e0
[ 159.027063]
[ 159.027064] stack backtrace:
[ 159.027172] Pid: 0, comm: swapper Not tainted
2.6.34-rc5-03707-gde498c8-dirty #36
[ 159.027252] Call Trace:
[ 159.027306] <IRQ> [<ffffffff810718ef>] lockdep_rcu_dereference
+0xaf/0xc0
[ 159.027411] [<ffffffff8138e4f7>] tcp_current_mss+0xa7/0xb0
[ 159.027537] [<ffffffff8138fa49>] tcp_write_wakeup+0x89/0x190
[ 159.027600] [<ffffffff81391936>] tcp_send_probe0+0x16/0x100
[ 159.027726] [<ffffffff81392cd9>] tcp_write_timer+0x179/0x1e0
[ 159.027790] [<ffffffff8104fca1>] run_timer_softirq+0x191/0x350
[ 159.027980] [<ffffffff810477ed>] __do_softirq+0xcd/0x200
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index 8ab0514..86a8ca1 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1197,7 +1197,8 @@
__sk_dst_get(struct sock *sk)
{
return rcu_dereference_check(sk->sk_dst_cache, rcu_read_lock_held() ||
- sock_owned_by_user(sk));
+ sock_owned_by_user(sk) ||
+ lockdep_is_held(&sk->sk_lock.slock));
}
static inline struct dst_entry *