rcu: Fix tracepoints & lockdep false positive
tracepoint.h uses rcu_dereference(), which 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> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4B9F48AD.4000404@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -49,7 +49,7 @@ struct tracepoint {
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void **it_func; \
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\
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rcu_read_lock_sched_notrace(); \
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it_func = rcu_dereference((tp)->funcs); \
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it_func = rcu_dereference_sched((tp)->funcs); \
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if (it_func) { \
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do { \
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((void(*)(proto))(*it_func))(args); \
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