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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2015-02-06 14:30:50 -0500
committerSteven Rostedt <rostedt@goodmis.org>2015-02-07 19:34:25 -0500
commita05d59a5673339ef6936d6940cdf68172ce75b9f (patch)
treef977bb1c09dd64b1def119467be15220fd3d592b /include/linux/tracepoint.h
parentce1039bd3a89e99e4f624e75fb1777fc92d76eb3 (diff)
downloadlinux-linaro-stable-a05d59a5673339ef6936d6940cdf68172ce75b9f.tar.gz
tracing: Add condition check to RCU lockdep checks
The trace_tlb_flush() tracepoint can be called when a CPU is going offline. When a CPU is offline, RCU is no longer watching that CPU and since the tracepoint is protected by RCU, it must not be called. To prevent the tlb_flush tracepoint from being called when the CPU is offline, it was converted to a TRACE_EVENT_CONDITION where the condition checks if the CPU is online before calling the tracepoint. Unfortunately, this was not enough to stop lockdep from complaining about it. Even though the RCU protected code of the tracepoint will never be called, the condition is hidden within the tracepoint, and even though the condition prevents RCU code from being called, the lockdep checks are outside the tracepoint (this is to test tracepoints even when they are not enabled). Even though tracepoints should be checked to be RCU safe when they are not enabled, the condition should still be considered when checking RCU. Link: http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=JB8B9a0EQv-eGzQ@mail.gmail.com Fixes: 3a630178fd5f "tracing: generate RCU warnings even when tracepoints are disabled" Cc: stable@vger.kernel.org # 3.18+ Acked-by: Dave Hansen <dave@sr71.net> Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/tracepoint.h')
-rw-r--r--include/linux/tracepoint.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index e08e21e5f601..c72851328ca9 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -173,7 +173,7 @@ extern void syscall_unregfunc(void);
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
TP_CONDITION(cond),,); \
- if (IS_ENABLED(CONFIG_LOCKDEP)) { \
+ if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
rcu_read_lock_sched_notrace(); \
rcu_dereference_sched(__tracepoint_##name.funcs);\
rcu_read_unlock_sched_notrace(); \