linux-kernel - [PATCH 03/19] jump_label: Expose the reference count

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Message-Id: <1399974350-11089-4-git-send-email-mgorman@suse.de>
Date:	Tue, 13 May 2014 10:45:34 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Johannes Weiner <hannes@...xchg.org>,
	Vlastimil Babka <vbabka@...e.cz>, Jan Kara <jack@...e.cz>,
	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Mel Gorman <mgorman@...e.de>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>,
	Linux-FSDevel <linux-fsdevel@...r.kernel.org>
Subject: [PATCH 03/19] jump_label: Expose the reference count

This patch exposes the jump_label reference count in preparation for the
next patch. cpusets cares about both the jump_label being enabled and how
many users of the cpusets there currently are.

Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 include/linux/jump_label.h | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 5c1dfb2..784304b 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -69,6 +69,10 @@ struct static_key {
 
 # include <asm/jump_label.h>
 # define HAVE_JUMP_LABEL
+#else
+struct static_key {
+	atomic_t enabled;
+};
 #endif	/* CC_HAVE_ASM_GOTO && CONFIG_JUMP_LABEL */
 
 enum jump_label_type {
@@ -79,6 +83,12 @@ enum jump_label_type {
 struct module;
 
 #include <linux/atomic.h>
+
+static inline int static_key_count(struct static_key *key)
+{
+	return atomic_read(&key->enabled);
+}
+
 #ifdef HAVE_JUMP_LABEL
 
 #define JUMP_LABEL_TYPE_FALSE_BRANCH	0UL
@@ -134,10 +144,6 @@ extern void jump_label_apply_nops(struct module *mod);
 
 #else  /* !HAVE_JUMP_LABEL */
 
-struct static_key {
-	atomic_t enabled;
-};
-
 static __always_inline void jump_label_init(void)
 {
 	static_key_initialized = true;
@@ -145,14 +151,14 @@ static __always_inline void jump_label_init(void)
 
 static __always_inline bool static_key_false(struct static_key *key)
 {
-	if (unlikely(atomic_read(&key->enabled) > 0))
+	if (unlikely(static_key_count(key) > 0))
 		return true;
 	return false;
 }
 
 static __always_inline bool static_key_true(struct static_key *key)
 {
-	if (likely(atomic_read(&key->enabled) > 0))
+	if (likely(static_key_count(key) > 0))
 		return true;
 	return false;
 }
@@ -194,7 +200,7 @@ static inline int jump_label_apply_nops(struct module *mod)
 
 static inline bool static_key_enabled(struct static_key *key)
 {
-	return (atomic_read(&key->enabled) > 0);
+	return static_key_count(key) > 0;
 }
 
 #endif	/* _LINUX_JUMP_LABEL_H */
-- 
1.8.4.5

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