1 files changed, 88 insertions, 32 deletions

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 6c9cb208ac48..0bf2e8f5244a 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -15,6 +15,7 @@
 #include <linux/static_key.h>
 #include <linux/jump_label_ratelimit.h>
 #include <linux/bug.h>
+#include <linux/cpu.h>
 
 #ifdef HAVE_JUMP_LABEL
 
@@ -78,29 +79,7 @@ int static_key_count(struct static_key *key)
 }
 EXPORT_SYMBOL_GPL(static_key_count);
 
-void static_key_enable(struct static_key *key)
-{
-	int count = static_key_count(key);
-
-	WARN_ON_ONCE(count < 0 || count > 1);
-
-	if (!count)
-		static_key_slow_inc(key);
-}
-EXPORT_SYMBOL_GPL(static_key_enable);
-
-void static_key_disable(struct static_key *key)
-{
-	int count = static_key_count(key);
-
-	WARN_ON_ONCE(count < 0 || count > 1);
-
-	if (count)
-		static_key_slow_dec(key);
-}
-EXPORT_SYMBOL_GPL(static_key_disable);
-
-void static_key_slow_inc(struct static_key *key)
+static void static_key_slow_inc_cpuslocked(struct static_key *key)
 {
 	int v, v1;
 
@@ -128,16 +107,82 @@ void static_key_slow_inc(struct static_key *key)
 	if (atomic_read(&key->enabled) == 0) {
 		atomic_set(&key->enabled, -1);
 		jump_label_update(key);
-		atomic_set(&key->enabled, 1);
+		/*
+		 * Ensure that if the above cmpxchg loop observes our positive
+		 * value, it must also observe all the text changes.
+		 */
+		atomic_set_release(&key->enabled, 1);
 	} else {
 		atomic_inc(&key->enabled);
 	}
 	jump_label_unlock();
 }
+
+void static_key_slow_inc(struct static_key *key)
+{
+	cpus_read_lock();
+	static_key_slow_inc_cpuslocked(key);
+	cpus_read_unlock();
+}
 EXPORT_SYMBOL_GPL(static_key_slow_inc);
 
-static void __static_key_slow_dec(struct static_key *key,
-		unsigned long rate_limit, struct delayed_work *work)
+void static_key_enable_cpuslocked(struct static_key *key)
+{
+	STATIC_KEY_CHECK_USE();
+
+	if (atomic_read(&key->enabled) > 0) {
+		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
+		return;
+	}
+
+	jump_label_lock();
+	if (atomic_read(&key->enabled) == 0) {
+		atomic_set(&key->enabled, -1);
+		jump_label_update(key);
+		/*
+		 * See static_key_slow_inc().
+		 */
+		atomic_set_release(&key->enabled, 1);
+	}
+	jump_label_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
+
+void static_key_enable(struct static_key *key)
+{
+	cpus_read_lock();
+	static_key_enable_cpuslocked(key);
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_enable);
+
+void static_key_disable_cpuslocked(struct static_key *key)
+{
+	STATIC_KEY_CHECK_USE();
+
+	if (atomic_read(&key->enabled) != 1) {
+		WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
+		return;
+	}
+
+	jump_label_lock();
+	if (atomic_cmpxchg(&key->enabled, 1, 0))
+		jump_label_update(key);
+	jump_label_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
+
+void static_key_disable(struct static_key *key)
+{
+	cpus_read_lock();
+	static_key_disable_cpuslocked(key);
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_disable);
+
+static void static_key_slow_dec_cpuslocked(struct static_key *key,
+					   unsigned long rate_limit,
+					   struct delayed_work *work)
 {
 	/*
 	 * The negative count check is valid even when a negative
@@ -161,6 +206,15 @@ static void __static_key_slow_dec(struct static_key *key,
 	jump_label_unlock();
 }
 
+static void __static_key_slow_dec(struct static_key *key,
+				  unsigned long rate_limit,
+				  struct delayed_work *work)
+{
+	cpus_read_lock();
+	static_key_slow_dec_cpuslocked(key, rate_limit, work);
+	cpus_read_unlock();
+}
+
 static void jump_label_update_timeout(struct work_struct *work)
 {
 	struct static_key_deferred *key =
@@ -334,6 +388,7 @@ void __init jump_label_init(void)
 	if (static_key_initialized)
 		return;
 
+	cpus_read_lock();
 	jump_label_lock();
 	jump_label_sort_entries(iter_start, iter_stop);
 
@@ -353,6 +408,7 @@ void __init jump_label_init(void)
 	}
 	static_key_initialized = true;
 	jump_label_unlock();
+	cpus_read_unlock();
 }
 
 #ifdef CONFIG_MODULES
@@ -590,28 +646,28 @@ jump_label_module_notify(struct notifier_block *self, unsigned long val,
 	struct module *mod = data;
 	int ret = 0;
 
+	cpus_read_lock();
+	jump_label_lock();
+
 	switch (val) {
 	case MODULE_STATE_COMING:
-		jump_label_lock();
 		ret = jump_label_add_module(mod);
 		if (ret) {
 			WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
 			jump_label_del_module(mod);
 		}
-		jump_label_unlock();
 		break;
 	case MODULE_STATE_GOING:
-		jump_label_lock();
 		jump_label_del_module(mod);
-		jump_label_unlock();
 		break;
 	case MODULE_STATE_LIVE:
-		jump_label_lock();
 		jump_label_invalidate_module_init(mod);
-		jump_label_unlock();
 		break;
 	}
 
+	jump_label_unlock();
+	cpus_read_unlock();
+
 	return notifier_from_errno(ret);
 }