linux-kernel - [PATCH 3.16 20/86] jump_label: make static_key_enabled() work on static_key

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Date:   Thu, 16 May 2019 16:55:33 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Tejun Heo" <tj@...nel.org>
Subject: [PATCH 3.16 20/86] jump_label: make static_key_enabled() work on
 static_key_true/false types too

3.16.68-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj@...nel.org>

commit fa128fd735bd236b6b04d3fedfed7a784137c185 upstream.

static_key_enabled() can be used on struct static_key but not on its
wrapper types static_key_true and static_key_false.  The function is
useful for debugging and management of static keys.  Update it so that
it can be used for the wrapper types too.

Signed-off-by: Tejun Heo <tj@...nel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 include/linux/jump_label.h | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -214,11 +214,6 @@ static inline int jump_label_apply_nops(
 #define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
 #define jump_label_enabled static_key_enabled
 
-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);
@@ -265,6 +260,17 @@ struct static_key_false {
 #define DEFINE_STATIC_KEY_FALSE(name)	\
 	struct static_key_false name = STATIC_KEY_FALSE_INIT
 
+extern bool ____wrong_branch_error(void);
+
+#define static_key_enabled(x)							\
+({										\
+	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) &&	\
+	    !__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
+	    !__builtin_types_compatible_p(typeof(*x), struct static_key_false))	\
+		____wrong_branch_error();					\
+	static_key_count((struct static_key *)x) > 0;				\
+})
+
 #ifdef HAVE_JUMP_LABEL
 
 /*
@@ -323,8 +329,6 @@ struct static_key_false {
  * See jump_label_type() / jump_label_init_type().
  */
 
-extern bool ____wrong_branch_error(void);
-
 #define static_branch_likely(x)							\
 ({										\
 	bool branch;								\