Messages in this thread | | | Date | Tue, 16 Mar 2010 09:08:14 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH -tip] rcu: fix lockdep for tracepoint |
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* Lai Jiangshan (laijs@cn.fujitsu.com) wrote: > tracepoint.h use rcu_dereference(), it triggers this warning: > > [ 0.701161] =================================================== > [ 0.702211] [ INFO: suspicious rcu_dereference_check() usage. ] > [ 0.702716] --------------------------------------------------- > [ 0.703203] include/trace/events/workqueue.h:68 invoked rcu_dereference_check() without protection! > [ 0.703971] > [ 0.703990] other info that might help us debug this: > [ 0.703993] > [ 0.705590] > [ 0.705604] rcu_scheduler_active = 1, debug_locks = 0 > [ 0.706712] 1 lock held by swapper/1: > [ 0.707229] #0: (cpu_add_remove_lock){+.+.+.}, at: [<c0142f54>] cpu_maps_update_begin+0x14/0x20 > [ 0.710097] > [ 0.710106] stack backtrace: > [ 0.712602] Pid: 1, comm: swapper Not tainted 2.6.34-rc1-tip-01613-g72662bb #168 > [ 0.713231] Call Trace: > [ 0.713997] [<c017174d>] lockdep_rcu_dereference+0x9d/0xb0 > [ 0.714746] [<c015a117>] create_workqueue_thread+0x107/0x110 > [ 0.715353] [<c015aee0>] ? worker_thread+0x0/0x340 > [ 0.715845] [<c015a8e8>] __create_workqueue_key+0x138/0x240 > [ 0.716427] [<c0142f92>] ? cpu_maps_update_done+0x12/0x20 > [ 0.717012] [<c086b12f>] init_workqueues+0x6f/0x80 > [ 0.717530] [<c08576d2>] kernel_init+0x102/0x1f0 > [ 0.717570] [<c08575d0>] ? kernel_init+0x0/0x1f0 > [ 0.718944] [<c01030fa>] kernel_thread_helper+0x6/0x10 > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Thanks Lai,
Mathieu
> --- > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index f59604e..78b4bd3 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -49,7 +49,7 @@ struct tracepoint { > void **it_func; \ > \ > rcu_read_lock_sched_notrace(); \ > - it_func = rcu_dereference((tp)->funcs); \ > + it_func = rcu_dereference_sched((tp)->funcs); \ > if (it_func) { \ > do { \ > ((void(*)(proto))(*it_func))(args); \ >
-- Mathieu Desnoyers Operating System Efficiency Consultant EfficiOS Inc. http://www.efficios.com
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