[tip:smp/hotplug] jump_label: Provide static_key_[disable|/slow_dec]_cpuslocked()

[tip-bot for Thomas Gleixner <tipbot@xxxxxxxxx>]

Commit-ID:  fc932a0477d0f16934847eacba1c8b7ccf71e650
Gitweb:     http://git.kernel.org/tip/fc932a0477d0f16934847eacba1c8b7ccf71e650
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Sun, 23 Apr 2017 11:12:31 +0200
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 23 Apr 2017 13:24:33 +0200

jump_label: Provide static_key_[disable|/slow_dec]_cpuslocked()

Provide static_key_[disable|slow_dec]_cpuslocked() variant that don't take
cpu_hotplug_lock().

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: jbaron@xxxxxxxxxx
---
 include/linux/jump_label.h | 12 ++++++++++--
 kernel/jump_label.c        | 18 +++++++++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 7d07f0b..6e3ebf2 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -160,10 +160,12 @@ extern int jump_label_text_reserved(void *start, void *end);
 extern void static_key_slow_inc(struct static_key *key);
 extern void static_key_slow_inc_cpuslocked(struct static_key *key);
 extern void static_key_slow_dec(struct static_key *key);
+extern void static_key_slow_dec_cpuslocked(struct static_key *key);
 extern void jump_label_apply_nops(struct module *mod);
 extern int static_key_count(struct static_key *key);
 extern void static_key_enable(struct static_key *key);
 extern void static_key_disable(struct static_key *key);
+extern void static_key_disable_cpuslocked(struct static_key *key);
 
 /*
  * We should be using ATOMIC_INIT() for initializing .enabled, but
@@ -255,6 +257,11 @@ static inline void static_key_disable(struct static_key *key)
 		static_key_slow_dec(key);
 }
 
+static inline void static_key_disable_cpuslocked(struct static_key *key)
+{
+	static_key_disable_cpuslocked(key);
+}
+
 #define STATIC_KEY_INIT_TRUE	{ .enabled = ATOMIC_INIT(1) }
 #define STATIC_KEY_INIT_FALSE	{ .enabled = ATOMIC_INIT(0) }
 
@@ -416,8 +423,9 @@ extern bool ____wrong_branch_error(void);
  * Normal usage; boolean enable/disable.
  */
 
-#define static_branch_enable(x)		static_key_enable(&(x)->key)
-#define static_branch_disable(x)	static_key_disable(&(x)->key)
+#define static_branch_enable(x)			static_key_enable(&(x)->key)
+#define static_branch_disable(x)		static_key_disable(&(x)->key)
+#define static_branch_disable_cpuslocked(x)	static_key_disable_cpuslocked(&(x)->key)
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 9455d2b..d71124e 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -101,6 +101,16 @@ void static_key_disable(struct static_key *key)
 }
 EXPORT_SYMBOL_GPL(static_key_disable);
 
+void static_key_disable_cpuslocked(struct static_key *key)
+{
+	int count = static_key_count(key);
+
+	WARN_ON_ONCE(count < 0 || count > 1);
+
+	if (count)
+		static_key_slow_dec_cpuslocked(key);
+}
+
 void __static_key_slow_inc(struct static_key *key)
 {
 	int v, v1;
@@ -159,7 +169,6 @@ EXPORT_SYMBOL_GPL(static_key_slow_inc_cpuslocked);
 static void __static_key_slow_dec(struct static_key *key,
 		unsigned long rate_limit, struct delayed_work *work)
 {
-	lockdep_assert_hotplug_held();
 	/*
 	 * The negative count check is valid even when a negative
 	 * key->enabled is in use by static_key_slow_inc(); a
@@ -173,6 +182,7 @@ static void __static_key_slow_dec(struct static_key *key,
 		return;
 	}
 
+	lockdep_assert_hotplug_held();
 	if (rate_limit) {
 		atomic_inc(&key->enabled);
 		schedule_delayed_work(work, rate_limit);
@@ -200,6 +210,12 @@ void static_key_slow_dec(struct static_key *key)
 }
 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 
+void static_key_slow_dec_cpuslocked(struct static_key *key)
+{
+	STATIC_KEY_CHECK_USE();
+	__static_key_slow_dec(key, 0, NULL);
+}
+
 void static_key_slow_dec_deferred(struct static_key_deferred *key)
 {
 	STATIC_KEY_CHECK_USE();
--
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