diff mbox

once: switch to new jump label API

Message ID 20170821234241.88438-1-ebiggers3@gmail.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Biggers Aug. 21, 2017, 11:42 p.m. UTC 
From: Eric Biggers <ebiggers@google.com>

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.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 include/linux/once.h | 6 +++---
 lib/once.c           | 8 ++++----
 2 files changed, 7 insertions(+), 7 deletions(-)

Comments

Hannes Frederic Sowa Aug. 22, 2017, 6:44 p.m. UTC | #1 
Eric Biggers <ebiggers3@gmail.com> writes:

> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org.

Thanks!
Eric Biggers Sept. 16, 2017, 4:07 a.m. UTC | #2 
On Tue, Aug 22, 2017 at 02:44:41PM -0400, Hannes Frederic Sowa wrote:
> Eric Biggers <ebiggers3@gmail.com> writes:
> 
> > From: Eric Biggers <ebiggers@google.com>
> >
> > 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.
> >
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org.
> 
> Thanks!

Great!  Who though is the maintainer for this code?  It seems it was originally
taken by David Miller through the networking tree.  David, are you taking
further patches to the "once" functions, or should I be trying to get this into
-mm, or somewhere else?

Eric
Eric Biggers Oct. 9, 2017, 8:27 p.m. UTC | #3 
On Fri, Sep 15, 2017 at 09:07:51PM -0700, Eric Biggers wrote:
> On Tue, Aug 22, 2017 at 02:44:41PM -0400, Hannes Frederic Sowa wrote:
> > Eric Biggers <ebiggers3@gmail.com> writes:
> > 
> > > From: Eric Biggers <ebiggers@google.com>
> > >
> > > 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.
> > >
> > > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > 
> > Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org.
> > 
> > Thanks!
> 
> Great!  Who though is the maintainer for this code?  It seems it was originally
> taken by David Miller through the networking tree.  David, are you taking
> further patches to the "once" functions, or should I be trying to get this into
> -mm, or somewhere else?
> 
> Eric

Ping.
Daniel Borkmann Oct. 9, 2017, 9:14 p.m. UTC | #4 
On 10/09/2017 10:27 PM, Eric Biggers wrote:
> On Fri, Sep 15, 2017 at 09:07:51PM -0700, Eric Biggers wrote:
>> On Tue, Aug 22, 2017 at 02:44:41PM -0400, Hannes Frederic Sowa wrote:
>>> Eric Biggers <ebiggers3@gmail.com> writes:
>>>> From: Eric Biggers <ebiggers@google.com>
>>>>
>>>> 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.
>>>>
>>>> Signed-off-by: Eric Biggers <ebiggers@google.com>
>>>
>>> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org.
>>>
>>> Thanks!
>>
>> Great!  Who though is the maintainer for this code?  It seems it was originally
>> taken by David Miller through the networking tree.  David, are you taking
>> further patches to the "once" functions, or should I be trying to get this into
>> -mm, or somewhere else?
>>
>> Eric
>
> Ping.

Given original code was accepted against net-next tree as major users of
the api are networking related anyway, it should be fine here as well to
route through this tree. Maybe resend the patch with a [PATCH net-next]
in the subject line (as usually done) to make the targeted tree more clear.
David Miller Oct. 9, 2017, 9:17 p.m. UTC | #5 
From: Daniel Borkmann <daniel@iogearbox.net>
Date: Mon, 09 Oct 2017 23:14:42 +0200

> Given original code was accepted against net-next tree as major
> users of the api are networking related anyway, it should be fine
> here as well to route through this tree. Maybe resend the patch with
> a [PATCH net-next] in the subject line (as usually done) to make the
> targeted tree more clear.

Indeed, please do, sorry for not replying.
diff mbox

Patch

diff --git a/include/linux/once.h b/include/linux/once.h
index 9c98aaa87cbc..724724918e8b 100644
--- 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 05c8604627eb..831c5a6b0bb2 100644
--- 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)
 {