linux-kernel - [PATCH v2 1/4] jump_label: Move cpu hotplug locking

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Message-Id: <20170801080257.5056-2-marc.zyngier@arm.com>
Date:   Tue,  1 Aug 2017 09:02:54 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v2 1/4] 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: Marc Zyngier <marc.zyngier@....com>
---
 kernel/jump_label.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index d11c506a6ac3..f11b10091100 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -105,6 +105,7 @@ void static_key_slow_inc(struct static_key *key)
 {
 	int v, v1;
 
+	cpus_read_lock();
 	STATIC_KEY_CHECK_USE();
 
 	/*
@@ -121,11 +122,12 @@ 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);
-- 
2.11.0