From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 24 Jul 2015 12:55:40 +0000 (+0200)
Subject: jump_label, locking/static_keys: Rename JUMP_LABEL_TYPE_* and related helpers to... 
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=a1efb01feca597b2abbc89873b40ef8ec6690168;p=openwrt%2Fstaging%2Fblogic.git

jump_label, locking/static_keys: Rename JUMP_LABEL_TYPE_* and related helpers to the static_key* pattern

Rename the JUMP_LABEL_TYPE_* macros to be JUMP_TYPE_* and move the
inline helpers into kernel/jump_label.c, since that's the only place
they're ever used.

Also rename the helpers where it's all about static keys.

This is the second step in removing the naming confusion that has led to
a stream of avoidable bugs such as:

  a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()")

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>
---

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 6a8b4fe10ad8..0ddb208b8449 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -101,24 +101,9 @@ static inline int static_key_count(struct static_key *key)
 
 #ifdef HAVE_JUMP_LABEL
 
-#define JUMP_LABEL_TYPE_FALSE_BRANCH	0UL
-#define JUMP_LABEL_TYPE_TRUE_BRANCH	1UL
-#define JUMP_LABEL_TYPE_MASK		1UL
-
-static
-inline struct jump_entry *jump_label_get_entries(struct static_key *key)
-{
-	return (struct jump_entry *)((unsigned long)key->entries
-						& ~JUMP_LABEL_TYPE_MASK);
-}
-
-static inline bool jump_label_get_branch_default(struct static_key *key)
-{
-	if (((unsigned long)key->entries & JUMP_LABEL_TYPE_MASK) ==
-	    JUMP_LABEL_TYPE_TRUE_BRANCH)
-		return true;
-	return false;
-}
+#define JUMP_TYPE_FALSE	0UL
+#define JUMP_TYPE_TRUE	1UL
+#define JUMP_TYPE_MASK	1UL
 
 static __always_inline bool static_key_false(struct static_key *key)
 {
@@ -147,10 +132,10 @@ extern void jump_label_apply_nops(struct module *mod);
 
 #define STATIC_KEY_INIT_TRUE ((struct static_key)		\
 	{ .enabled = ATOMIC_INIT(1),				\
-	  .entries = (void *)JUMP_LABEL_TYPE_TRUE_BRANCH })
+	  .entries = (void *)JUMP_TYPE_TRUE })
 #define STATIC_KEY_INIT_FALSE ((struct static_key)		\
 	{ .enabled = ATOMIC_INIT(0),				\
-	  .entries = (void *)JUMP_LABEL_TYPE_FALSE_BRANCH })
+	  .entries = (void *)JUMP_TYPE_FALSE })
 
 #else  /* !HAVE_JUMP_LABEL */
 
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 96d8945c8bf3..85a2a0086c67 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -56,6 +56,11 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 
 static void jump_label_update(struct static_key *key, int enable);
 
+static inline bool static_key_type(struct static_key *key)
+{
+	return (unsigned long)key->entries & JUMP_TYPE_MASK;
+}
+
 void static_key_slow_inc(struct static_key *key)
 {
 	STATIC_KEY_CHECK_USE();
@@ -64,7 +69,7 @@ void static_key_slow_inc(struct static_key *key)
 
 	jump_label_lock();
 	if (atomic_read(&key->enabled) == 0) {
-		if (!jump_label_get_branch_default(key))
+		if (!static_key_type(key))
 			jump_label_update(key, JUMP_LABEL_JMP);
 		else
 			jump_label_update(key, JUMP_LABEL_NOP);
@@ -87,7 +92,7 @@ static void __static_key_slow_dec(struct static_key *key,
 		atomic_inc(&key->enabled);
 		schedule_delayed_work(work, rate_limit);
 	} else {
-		if (!jump_label_get_branch_default(key))
+		if (!static_key_type(key))
 			jump_label_update(key, JUMP_LABEL_NOP);
 		else
 			jump_label_update(key, JUMP_LABEL_JMP);
@@ -178,15 +183,17 @@ static void __jump_label_update(struct static_key *key,
 	}
 }
 
-static enum jump_label_type jump_label_type(struct static_key *key)
+static inline struct jump_entry *static_key_entries(struct static_key *key)
 {
-	bool true_branch = jump_label_get_branch_default(key);
-	bool state = static_key_enabled(key);
+	return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
+}
 
-	if ((!true_branch && state) || (true_branch && !state))
-		return JUMP_LABEL_JMP;
+static enum jump_label_type jump_label_type(struct static_key *key)
+{
+	bool enabled = static_key_enabled(key);
+	bool type = static_key_type(key);
 
-	return JUMP_LABEL_NOP;
+	return enabled ^ type;
 }
 
 void __init jump_label_init(void)
@@ -442,7 +449,7 @@ int jump_label_text_reserved(void *start, void *end)
 static void jump_label_update(struct static_key *key, int enable)
 {
 	struct jump_entry *stop = __stop___jump_table;
-	struct jump_entry *entry = jump_label_get_entries(key);
+	struct jump_entry *entry = static_key_entries(key);
 #ifdef CONFIG_MODULES
 	struct module *mod;