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authorEric Dumazet <edumazet@google.com>2015-05-21 13:28:29 -0700
committerDavid S. Miller <davem@davemloft.net>2015-05-22 16:23:56 -0400
commit93a33a584e2a49a217118148125944fd02d47b54 (patch)
treef17e99cdf04cd70dae7b53c1fc91729cc3ff2aa0 /net
parentf96dee13b8e10f00840124255bed1d8b4c6afd6f (diff)
downloadkernel-93a33a584e2a49a217118148125944fd02d47b54.tar.gz
bridge: fix lockdep splat
Following lockdep splat was reported : [ 29.382286] =============================== [ 29.382315] [ INFO: suspicious RCU usage. ] [ 29.382344] 4.1.0-0.rc0.git11.1.fc23.x86_64 #1 Not tainted [ 29.382380] ------------------------------- [ 29.382409] net/bridge/br_private.h:626 suspicious rcu_dereference_check() usage! [ 29.382455] other info that might help us debug this: [ 29.382507] rcu_scheduler_active = 1, debug_locks = 0 [ 29.382549] 2 locks held by swapper/0/0: [ 29.382576] #0: (((&p->forward_delay_timer))){+.-...}, at: [<ffffffff81139f75>] call_timer_fn+0x5/0x4f0 [ 29.382660] #1: (&(&br->lock)->rlock){+.-...}, at: [<ffffffffa0450dc1>] br_forward_delay_timer_expired+0x31/0x140 [bridge] [ 29.382754] stack backtrace: [ 29.382787] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-0.rc0.git11.1.fc23.x86_64 #1 [ 29.382838] Hardware name: LENOVO 422916G/LENOVO, BIOS A1KT53AUS 04/07/2015 [ 29.382882] 0000000000000000 3ebfc20364115825 ffff880666603c48 ffffffff81892d4b [ 29.382943] 0000000000000000 ffffffff81e124e0 ffff880666603c78 ffffffff8110bcd7 [ 29.383004] ffff8800785c9d00 ffff88065485ac58 ffff880c62002800 ffff880c5fc88ac0 [ 29.383065] Call Trace: [ 29.383084] <IRQ> [<ffffffff81892d4b>] dump_stack+0x4c/0x65 [ 29.383130] [<ffffffff8110bcd7>] lockdep_rcu_suspicious+0xe7/0x120 [ 29.383178] [<ffffffffa04520f9>] br_fill_ifinfo+0x4a9/0x6a0 [bridge] [ 29.383225] [<ffffffffa045266b>] br_ifinfo_notify+0x11b/0x4b0 [bridge] [ 29.383271] [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge] [ 29.383320] [<ffffffffa0450de8>] br_forward_delay_timer_expired+0x58/0x140 [bridge] [ 29.383371] [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge] [ 29.383416] [<ffffffff8113a033>] call_timer_fn+0xc3/0x4f0 [ 29.383454] [<ffffffff81139f75>] ? call_timer_fn+0x5/0x4f0 [ 29.383493] [<ffffffff8110a90f>] ? lock_release_holdtime.part.29+0xf/0x200 [ 29.383541] [<ffffffffa0450d90>] ? br_hold_timer_expired+0x70/0x70 [bridge] [ 29.383587] [<ffffffff8113a6a4>] run_timer_softirq+0x244/0x490 [ 29.383629] [<ffffffff810b68cc>] __do_softirq+0xec/0x670 [ 29.383666] [<ffffffff810b70d5>] irq_exit+0x145/0x150 [ 29.383703] [<ffffffff8189f506>] smp_apic_timer_interrupt+0x46/0x60 [ 29.383744] [<ffffffff8189d523>] apic_timer_interrupt+0x73/0x80 [ 29.383782] <EOI> [<ffffffff816f131f>] ? cpuidle_enter_state+0x5f/0x2f0 [ 29.383832] [<ffffffff816f131b>] ? cpuidle_enter_state+0x5b/0x2f0 Problem here is that br_forward_delay_timer_expired() is a timer handler, calling br_ifinfo_notify() which assumes either rcu_read_lock() or RTNL are held. Simplest fix seems to add rcu read lock section. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Reported-by: Dominick Grift <dac.override@gmail.com> Cc: Vlad Yasevich <vyasevich@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/bridge/br_stp_timer.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/bridge/br_stp_timer.c b/net/bridge/br_stp_timer.c
index 4fcaa67750fd..7caf7fae2d5b 100644
--- a/net/bridge/br_stp_timer.c
+++ b/net/bridge/br_stp_timer.c
@@ -97,7 +97,9 @@ static void br_forward_delay_timer_expired(unsigned long arg)
netif_carrier_on(br->dev);
}
br_log_state(p);
+ rcu_read_lock();
br_ifinfo_notify(RTM_NEWLINK, p);
+ rcu_read_unlock();
spin_unlock(&br->lock);
}