sched: Mark sched_clock() as notrace

The core ftrace code (trace_clock_local) calls sched_clock()
directly, so we don't want to recurisvely trigger the ftrace
code.  Rather than update every sched_clock() definition, tag
the prototype for everyone as notrace.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1260407223-10900-1-git-send-email-vapier@gentoo.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -1836,7 +1836,8 @@ static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
 extern int sched_clock_stable;
 #endif
 
-extern unsigned long long sched_clock(void);
+/* ftrace calls sched_clock() directly */
+extern unsigned long long notrace sched_clock(void);
 
 extern void sched_clock_init(void);
 extern u64 sched_clock_cpu(int cpu);