lkml.org 
[lkml]   [2010]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH -tip] rcu: fix lockdep for tracepoint
* 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


\
 
 \ /
  Last update: 2010-03-16 14:11    [W:0.044 / U:0.588 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site