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Eric Dumazet 93a33a584e 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>
 		2015-05-22 16:23:56 -04:00
..
netfilter netfilter: ensure number of counters is >0 in do_replace() 2015-05-20 13:46:49 +02:00
Kconfig bridge: Add vlan filtering infrastructure 2013-02-13 19:41:46 -05:00
Makefile netfilter: bridge: build br_nf_core only if required 2014-09-30 14:07:51 -04:00
br.c net: bridge: add compile-time assert for cb struct size 2015-03-03 14:07:04 -05:00
br_device.c netfilter: bridge: use rcu hook to resolve br_netfilter dependency 2015-03-10 15:03:02 +01:00
br_fdb.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-02-09 14:35:57 -08:00
br_forward.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
br_if.c bridge: reset bridge mtu after deleting an interface 2015-03-14 19:12:38 -04:00
br_input.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
br_ioctl.c bridge: add space before '(/{', after ',', etc. 2013-12-19 19:27:26 -05:00
br_mdb.c bridge/mdb: remove wrong use of NLM_F_MULTI 2015-04-29 14:59:16 -04:00
br_multicast.c bridge: fix parsing of MLDv2 reports 2015-05-22 15:08:20 -04:00
br_netfilter.c Revert "netfilter: bridge: query conntrack about skb dnat" 2015-05-20 13:51:25 +02:00
br_netlink.c bridge/nl: remove wrong use of NLM_F_MULTI 2015-04-29 14:59:16 -04:00
br_nf_core.c net: Remove protocol from struct dst_ops 2015-03-09 16:06:10 -04:00
br_private.h bridge/nl: remove wrong use of NLM_F_MULTI 2015-04-29 14:59:16 -04:00
br_private_stp.h net: 8021q/bluetooth/bridge/can/ceph: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
br_stp.c bridge: call netdev_sw_port_stp_update when bridge port STP status changes 2014-12-02 20:01:22 -08:00
br_stp_bpdu.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
br_stp_if.c net: bridge: add a br_set_state helper function 2014-10-01 22:03:50 -04:00
br_stp_timer.c bridge: fix lockdep splat 2015-05-22 16:23:56 -04:00
br_sysfs_br.c bridge: Add a default_pvid sysfs attribute 2014-10-05 21:21:36 -04:00
br_sysfs_if.c bridge: Extend Proxy ARP design to allow optional rules for Wi-Fi 2015-03-05 14:52:23 -05:00
br_vlan.c net: rename vlan_tx_* helpers since "tx" is misleading there 2015-01-13 17:51:08 -05:00