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Subject[PATCH 3.12 024/142] locking/static_keys: Add static_key_{en,dis}able() helpers
Date
From: Peter Zijlstra <peterz@infradead.org>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit e33886b38cc82a9fc3b2d655dfc7f50467594138 upstream.

Add two helpers to make it easier to treat the refcount as boolean.

[js] do not involve WARN_ON_ONCE as it causes build failures

Suggested-by: Jason Baron <jasonbaron0@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
include/linux/jump_label.h | 16 ++++++++++++++++
kernel/sched/core.c | 6 ++----
2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 9216e465289a..6fdea8105f45 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -188,4 +188,20 @@ static inline bool static_key_enabled(struct static_key *key)
return static_key_count(key) > 0;
}

+static inline void static_key_enable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ if (!count)
+ static_key_slow_inc(key);
+}
+
+static inline void static_key_disable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ if (count)
+ static_key_slow_dec(key);
+}
+
#endif /* _LINUX_JUMP_LABEL_H */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 426193802b1f..602b6c08c47d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -179,14 +179,12 @@ struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {

static void sched_feat_disable(int i)
{
- if (static_key_enabled(&sched_feat_keys[i]))
- static_key_slow_dec(&sched_feat_keys[i]);
+ static_key_disable(&sched_feat_keys[i]);
}

static void sched_feat_enable(int i)
{
- if (!static_key_enabled(&sched_feat_keys[i]))
- static_key_slow_inc(&sched_feat_keys[i]);
+ static_key_enable(&sched_feat_keys[i]);
}
#else
static void sched_feat_disable(int i) { };
--
2.12.2
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