From: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
Date: Sat, 31 Aug 2013 05:04:07 +0000 (-0400)
Subject: ftrace/rcu: Do not trace debug_lockdep_rcu_enabled()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a0a5a0561f63905fe94c49bc567615829f42ce1e;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

ftrace/rcu: Do not trace debug_lockdep_rcu_enabled()

The function debug_lockdep_rcu_enabled() is part of the RCU lockdep
debugging, and is called very frequently. I found that if I enable
a lot of debugging and run the function graph tracer, this
function can cause a live lock of the system.

We don't usually trace lockdep infrastructure, no need to trace
this either.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index cce6ba8bbace..4f20c6c6a848 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -122,7 +122,7 @@ struct lockdep_map rcu_sched_lock_map =
 	STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
 EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
 
-int debug_lockdep_rcu_enabled(void)
+int notrace debug_lockdep_rcu_enabled(void)
 {
 	return rcu_scheduler_active && debug_locks &&
 	       current->lockdep_recursion == 0;