once: switch to new jump label API

Switch the DO_ONCE() macro from the deprecated jump label API to the new
one.  The new one is more readable, and for DO_ONCE() it also makes the
generated code more icache-friendly: now the one-time initialization
code is placed out-of-line at the jump target, rather than at the inline
fallthrough case.

Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/once.h b/include/linux/once.h
index 9c98aaa87cbcd4f26b8ecdc25b93fae555ab4daa..724724918e8bc559e8c6ba20d7c9b5bf77a8b0ae 100644 (file)
--- a/include/linux/once.h
+++ b/include/linux/once.h
@@ -5,7 +5,7 @@
 #include <linux/jump_label.h>
 
 bool __do_once_start(bool *done, unsigned long *flags);
-void __do_once_done(bool *done, struct static_key *once_key,
+void __do_once_done(bool *done, struct static_key_true *once_key,
                    unsigned long *flags);
 
 /* Call a function exactly once. The idea of DO_ONCE() is to perform
@@ -38,8 +38,8 @@ void __do_once_done(bool *done, struct static_key *once_key,
        ({                                                                   \
                bool ___ret = false;                                         \
                static bool ___done = false;                                 \
-               static struct static_key ___once_key = STATIC_KEY_INIT_TRUE; \
-               if (static_key_true(&___once_key)) {                         \
+               static DEFINE_STATIC_KEY_TRUE(___once_key);                  \
+               if (static_branch_unlikely(&___once_key)) {                  \
                        unsigned long ___flags;                              \
                        ___ret = __do_once_start(&___done, &___flags);       \
                        if (unlikely(___ret)) {                              \

diff --git a/lib/once.c b/lib/once.c
index 05c8604627eb0ae085913a91a17013604e83f359..831c5a6b0bb2da350cbcd8ae80e224188694e7f0 100644 (file)
--- a/lib/once.c
+++ b/lib/once.c
@@ -5,7 +5,7 @@
 
 struct once_work {
        struct work_struct work;
-       struct static_key *key;
+       struct static_key_true *key;
 };
 
 static void once_deferred(struct work_struct *w)
@@ -14,11 +14,11 @@ static void once_deferred(struct work_struct *w)
 
        work = container_of(w, struct once_work, work);
        BUG_ON(!static_key_enabled(work->key));
-       static_key_slow_dec(work->key);
+       static_branch_disable(work->key);
        kfree(work);
 }
 
-static void once_disable_jump(struct static_key *key)
+static void once_disable_jump(struct static_key_true *key)
 {
        struct once_work *w;
 
@@ -51,7 +51,7 @@ bool __do_once_start(bool *done, unsigned long *flags)
 }
 EXPORT_SYMBOL(__do_once_start);
 
-void __do_once_done(bool *done, struct static_key *once_key,
+void __do_once_done(bool *done, struct static_key_true *once_key,
                    unsigned long *flags)
        __releases(once_lock)
 {