rcu: Add "notrace" to RCU function headers used by ftrace

Both rcu_read_lock_sched_notrace() and
rcu_read_unlock_sched_notrace() are used by ftrace, and thus
need to be marked "notrace".

Unfortunately, my naive assumption that gcc would see the inner
"notrace" does not hold.

Kudos to Lai Jiangshan for noting this.
Reported-by: NIngo Molnar <mingo@elte.hu>
Bug-spotted-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <12511321213243-git-send-email->
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/rcupdate.h

@@ -191,7 +191,7 @@ static inline void rcu_read_lock_sched(void)
 	__acquire(RCU_SCHED);
 	rcu_read_acquire();
 }
-static inline void rcu_read_lock_sched_notrace(void)
+static inline notrace void rcu_read_lock_sched_notrace(void)
 {
 	preempt_disable_notrace();
 	__acquire(RCU_SCHED);
@@ -209,7 +209,7 @@ static inline void rcu_read_unlock_sched(void)
 	__release(RCU_SCHED);
 	preempt_enable();
 }
-static inline void rcu_read_unlock_sched_notrace(void)
+static inline notrace void rcu_read_unlock_sched_notrace(void)
 {
 	rcu_read_release();
 	__release(RCU_SCHED);