jump_label: Move CPU hotplug locking

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: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NPeter 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.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

kernel/jump_label.c

@@ -83,6 +83,7 @@ void static_key_slow_inc(struct static_key *key)
 {
 	int v, v1;
 
+	cpus_read_lock();
 	STATIC_KEY_CHECK_USE();
 
 	/*
@@ -99,11 +100,12 @@ void static_key_slow_inc(struct static_key *key)
 	 */
 	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);