[tip:sched/core] sched/clock: Add dummy clear_sched_clock_stable() stub function

[tip-bot for Paul Gortmaker <tipbot@zytor.com>]

Commit-ID:  733ce725aa4bfa9063be053bfe7f4597d76f0dd1
Gitweb:     http://git.kernel.org/tip/733ce725aa4bfa9063be053bfe7f4597d76f0dd1
Author:     Paul Gortmaker <paul.gortmaker@windriver.com>
AuthorDate: Fri, 27 Jan 2017 12:38:16 -0500
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 1 Feb 2017 11:01:29 +0100

sched/clock: Add dummy clear_sched_clock_stable() stub function

In commit:

  acb04058de494 ("sched/clock: Fix hotplug crash")

the PARISC code gained a call to this function.

However the prototype for it is within a CONFIG_HAVE_UNSTABLE_SCHED_CLOCK=y
 #ifdef/#endif.  That, combined with this:

  arch/parisc/Kconfig:    select HAVE_UNSTABLE_SCHED_CLOCK if SMP

means that PARISC can have it either enabled or disabled, resulting
in the following build fail:

  arch/parisc/kernel/setup.c:180:2: error: implicit declaration of
  function 'clear_sched_clock_stable' [-Werror=implicit-function-declaration]

Add a no-op stub for the non-SMP case to prevent this.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: acb04058de49 ("sched/clock: Fix hotplug crash")
Link: http://lkml.kernel.org/r/20170127173816.22733-1-paul.gortmaker@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/sched.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d176454..e2ed46d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2511,6 +2511,10 @@ static inline void sched_clock_tick(void)
 {
 }
 
+static inline void clear_sched_clock_stable(void)
+{
+}
+
 static inline void sched_clock_idle_sleep_event(void)
 {
 }