2 files changed, 76 insertions, 23 deletions

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 68904469fba1..661af564fae8 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -76,7 +76,6 @@
 
 #include <linux/types.h>
 #include <linux/compiler.h>
-#include <linux/bug.h>
 
 extern bool static_key_initialized;
 
@@ -115,20 +114,8 @@ enum jump_label_type {
 
 struct module;
 
-#include <linux/atomic.h>
-
 #ifdef HAVE_JUMP_LABEL
 
-static inline int static_key_count(struct static_key *key)
-{
-        /*
-         * -1 means the first static_key_slow_inc() is in progress.
-         *  static_key_enabled() must return true, so return 1 here.
-         */
-        int n = atomic_read(&key->enabled);
-        return n >= 0 ? n : 1;
-}
-
 #define JUMP_TYPE_FALSE 0UL
 #define JUMP_TYPE_TRUE  1UL
 #define JUMP_TYPE_MASK  1UL
@@ -157,16 +144,29 @@ 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_dec(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);
 
+/*
+ * We should be using ATOMIC_INIT() for initializing .enabled, but
+ * the inclusion of atomic.h is problematic for inclusion of jump_label.h
+ * in 'low-level' headers. Thus, we are initializing .enabled with a
+ * raw value, but have added a BUILD_BUG_ON() to catch any issues in
+ * jump_label_init() see: kernel/jump_label.c.
+ */
 #define STATIC_KEY_INIT_TRUE                                    \
-        { .enabled = ATOMIC_INIT(1),                            \
+        { .enabled = { 1 },                                     \
           .entries = (void *)JUMP_TYPE_TRUE }
 #define STATIC_KEY_INIT_FALSE                                   \
-        { .enabled = ATOMIC_INIT(0),                            \
+        { .enabled = { 0 },                                     \
           .entries = (void *)JUMP_TYPE_FALSE }
 
 #else  /* !HAVE_JUMP_LABEL */
 
+#include <linux/atomic.h>
+#include <linux/bug.h>
+
 static inline int static_key_count(struct static_key *key)
 {
         return atomic_read(&key->enabled);
@@ -216,14 +216,6 @@ static inline int jump_label_apply_nops(struct module *mod)
         return 0;
 }
 
-#define STATIC_KEY_INIT_TRUE    { .enabled = ATOMIC_INIT(1) }
-#define STATIC_KEY_INIT_FALSE   { .enabled = ATOMIC_INIT(0) }
-
-#endif  /* HAVE_JUMP_LABEL */
-
-#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
-#define jump_label_enabled static_key_enabled
-
 static inline void static_key_enable(struct static_key *key)
 {
         int count = static_key_count(key);
@@ -244,6 +236,14 @@ static inline void static_key_disable(struct static_key *key)
                 static_key_slow_dec(key);
 }
 
+#define STATIC_KEY_INIT_TRUE    { .enabled = ATOMIC_INIT(1) }
+#define STATIC_KEY_INIT_FALSE   { .enabled = ATOMIC_INIT(0) }
+
+#endif  /* HAVE_JUMP_LABEL */
+
+#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
+#define jump_label_enabled static_key_enabled
+
 /* -------------------------------------------------------------------------- */
 
 /*
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0dbea887d625..f19aa02a8f48 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/static_key.h>
 #include <linux/jump_label_ratelimit.h>
+#include <linux/bug.h>
 
 #ifdef HAVE_JUMP_LABEL
 
@@ -56,6 +57,49 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 
 static void jump_label_update(struct static_key *key);
 
+/*
+ * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
+ * The use of 'atomic_read()' requires atomic.h and its problematic for some
+ * kernel headers such as kernel.h and others. Since static_key_count() is not
+ * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
+ * to have it be a function here. Similarly, for 'static_key_enable()' and
+ * 'static_key_disable()', which require bug.h. This should allow jump_label.h
+ * to be included from most/all places for HAVE_JUMP_LABEL.
+ */
+int static_key_count(struct static_key *key)
+{
+        /*
+         * -1 means the first static_key_slow_inc() is in progress.
+         *  static_key_enabled() must return true, so return 1 here.
+         */
+        int n = atomic_read(&key->enabled);
+
+        return n >= 0 ? n : 1;
+}
+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)
 {
         int v, v1;
@@ -235,6 +279,15 @@ void __init jump_label_init(void)
         struct static_key *key = NULL;
         struct jump_entry *iter;
 
+        /*
+         * Since we are initializing the static_key.enabled field with
+         * with the 'raw' int values (to avoid pulling in atomic.h) in
+         * jump_label.h, let's make sure that is safe. There are only two
+         * cases to check since we initialize to 0 or 1.
+         */
+        BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
+        BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
+
         jump_label_lock();
         jump_label_sort_entries(iter_start, iter_stop);