From: Marc Zyngier <marc.zyngier@arm.com>
Date: Tue, 1 Aug 2017 09:02:54 +0100
Subject: jump_label: Move CPU hotplug locking
Patch-mainline: v4.14-rc1
Git-commit: b70cecf4b6b72a9977576ab32cca0e24f286f517
References: bsc#1109837

As we're about to rework the locking, let's move the taking and
release of the CPU hotplug lock to locations that will make its
reworking completely obvious.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170801080257.5056-2-marc.zyngier@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/jump_label.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -83,6 +83,7 @@ void static_key_slow_inc(struct static_k
 {
 	int v, v1;
 
+	cpus_read_lock();
 	STATIC_KEY_CHECK_USE();
 
 	/*
@@ -99,11 +100,12 @@ void static_key_slow_inc(struct static_k
 	 */
 	for (v = atomic_read(&key->enabled); v > 0; v = v1) {
 		v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
-		if (likely(v1 == v))
+		if (likely(v1 == v)) {
+			cpus_read_unlock();
 			return;
+		}
 	}
 
-	cpus_read_lock();
 	jump_label_lock();
 	if (atomic_read(&key->enabled) == 0) {
 		atomic_set(&key->enabled, -1);