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Commit cf4c950b authored by Eric Biggers's avatar Eric Biggers Committed by David S. Miller
Browse files

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: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d93fa2ba

include/linux/once.h

+3 −3
Original line number Diff line number Diff line
@@ -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)) {				     \

lib/once.c

+4 −4
Original line number Diff line number Diff line
@@ -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)

{