On Tue, Jul 28, 2015 at 03:20:55PM +0200, Peter Zijlstra wrote:
> Hi all,
>
> After yet another bug because of the weirdness of the static key interface,
> here an attempt at providing a better one.
>
> This series is tested on x86_64 (by me) and s390x (heiko).
Works nice. You may include the s390 patch below, so the conversion to the
new interface happens when your code gets merged:
>From 3c9b5a2b9a90d6bb2b41f381f5f89b3657fe4ea5 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carst...@de.ibm.com>
Date: Wed, 29 Jul 2015 08:31:24 +0200
Subject: [PATCH] s390/uaccess: employ static_branch_likely()
Use the new static_branch_likely() primitive to make sure that the
most likely case is executed without taking an unconditional branch.
This wasn't possible with the old jump label primitives.
Signed-off-by: Heiko Carstens <heiko.carst...@de.ibm.com>
---
arch/s390/lib/uaccess.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index 4614d415bb58..93cb1d09493d 100644
--- a/arch/s390/lib/uaccess.c
+++ b/arch/s390/lib/uaccess.c
@@ -15,7 +15,7 @@
#include <asm/mmu_context.h>
#include <asm/facility.h>
-static struct static_key have_mvcos = STATIC_KEY_INIT_FALSE;
+static DEFINE_STATIC_KEY_FALSE(have_mvcos);
static inline unsigned long copy_from_user_mvcos(void *x, const void __user
*ptr,
unsigned long size)
@@ -104,7 +104,7 @@ static inline unsigned long copy_from_user_mvcp(void *x,
const void __user *ptr,
unsigned long __copy_from_user(void *to, const void __user *from, unsigned
long n)
{
- if (static_key_false(&have_mvcos))
+ if (static_branch_likely(&have_mvcos))
return copy_from_user_mvcos(to, from, n);
return copy_from_user_mvcp(to, from, n);
}
@@ -177,7 +177,7 @@ static inline unsigned long copy_to_user_mvcs(void __user
*ptr, const void *x,
unsigned long __copy_to_user(void __user *to, const void *from, unsigned long
n)
{
- if (static_key_false(&have_mvcos))
+ if (static_branch_likely(&have_mvcos))
return copy_to_user_mvcos(to, from, n);
return copy_to_user_mvcs(to, from, n);
}
@@ -240,7 +240,7 @@ static inline unsigned long copy_in_user_mvc(void __user
*to, const void __user
unsigned long __copy_in_user(void __user *to, const void __user *from,
unsigned long n)
{
- if (static_key_false(&have_mvcos))
+ if (static_branch_likely(&have_mvcos))
return copy_in_user_mvcos(to, from, n);
return copy_in_user_mvc(to, from, n);
}
@@ -312,7 +312,7 @@ static inline unsigned long clear_user_xc(void __user *to,
unsigned long size)
unsigned long __clear_user(void __user *to, unsigned long size)
{
- if (static_key_false(&have_mvcos))
+ if (static_branch_likely(&have_mvcos))
return clear_user_mvcos(to, size);
return clear_user_xc(to, size);
}
@@ -386,7 +386,7 @@ early_param("uaccess_primary", parse_uaccess_pt);
static int __init uaccess_init(void)
{
if (!uaccess_primary && test_facility(27))
- static_key_slow_inc(&have_mvcos);
+ static_branch_enable(&have_mvcos);
return 0;
}
early_initcall(uaccess_init);
--
2.3.8
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
