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Date: Fri, 11 Jul 2014 11:51:41 +0200
From: Borislav Petkov <bp@...en8.de>
To: Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: Get rid of __HAVE_ARCH_CMPXCHG
From: Borislav Petkov <bp@...e.de>
Both the 32-bit and 64-bit cmpxchg.h header define __HAVE_ARCH_CMPXCHG
and there's ifdeffery which checks it. But since both bitness define it,
we can just as well drop it and simpify a bit of code in doing that.
Signed-off-by: Borislav Petkov <bp@...e.de>
---
arch/x86/include/asm/cmpxchg.h | 2 --
arch/x86/include/asm/cmpxchg_32.h | 2 --
arch/x86/include/asm/cmpxchg_64.h | 2 --
arch/x86/include/asm/mc146818rtc.h | 2 +-
arch/x86/include/asm/mutex_32.h | 16 ++--------------
arch/x86/kernel/acpi/boot.c | 4 ----
kernel/locking/rtmutex.c | 2 +-
7 files changed, 4 insertions(+), 26 deletions(-)
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index d47786acb016..ad19841eddfe 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -143,7 +143,6 @@ extern void __add_wrong_size(void)
# include <asm/cmpxchg_64.h>
#endif
-#ifdef __HAVE_ARCH_CMPXCHG
#define cmpxchg(ptr, old, new) \
__cmpxchg(ptr, old, new, sizeof(*(ptr)))
@@ -152,7 +151,6 @@ extern void __add_wrong_size(void)
#define cmpxchg_local(ptr, old, new) \
__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))
-#endif
/*
* xadd() adds "inc" to "*ptr" and atomically returns the previous
diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index f8bf2eecab86..f7e142926481 100644
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -34,8 +34,6 @@ static inline void set_64bit(volatile u64 *ptr, u64 value)
: "memory");
}
-#define __HAVE_ARCH_CMPXCHG 1
-
#ifdef CONFIG_X86_CMPXCHG64
#define cmpxchg64(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg64((ptr), (unsigned long long)(o), \
diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
index 614be87f1a9b..1af94697aae5 100644
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -6,8 +6,6 @@ static inline void set_64bit(volatile u64 *ptr, u64 val)
*ptr = val;
}
-#define __HAVE_ARCH_CMPXCHG 1
-
#define cmpxchg64(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
diff --git a/arch/x86/include/asm/mc146818rtc.h b/arch/x86/include/asm/mc146818rtc.h
index a55c7efcc4ed..0f555cc31984 100644
--- a/arch/x86/include/asm/mc146818rtc.h
+++ b/arch/x86/include/asm/mc146818rtc.h
@@ -13,7 +13,7 @@
#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
#endif
-#if defined(CONFIG_X86_32) && defined(__HAVE_ARCH_CMPXCHG)
+#if defined(CONFIG_X86_32)
/*
* This lock provides nmi access to the CMOS/RTC registers. It has some
* special properties. It is owned by a CPU and stores the index register
diff --git a/arch/x86/include/asm/mutex_32.h b/arch/x86/include/asm/mutex_32.h
index 0208c3c2cbc6..85e6cda45a02 100644
--- a/arch/x86/include/asm/mutex_32.h
+++ b/arch/x86/include/asm/mutex_32.h
@@ -100,23 +100,11 @@ do { \
static inline int __mutex_fastpath_trylock(atomic_t *count,
int (*fail_fn)(atomic_t *))
{
- /*
- * We have two variants here. The cmpxchg based one is the best one
- * because it never induce a false contention state. It is included
- * here because architectures using the inc/dec algorithms over the
- * xchg ones are much more likely to support cmpxchg natively.
- *
- * If not we fall back to the spinlock based variant - that is
- * just as efficient (and simpler) as a 'destructive' probing of
- * the mutex state would be.
- */
-#ifdef __HAVE_ARCH_CMPXCHG
+ /* cmpxchg because it never induces a false contention state. */
if (likely(atomic_cmpxchg(count, 1, 0) == 1))
return 1;
+
return 0;
-#else
- return fail_fn(count);
-#endif
}
#endif /* _ASM_X86_MUTEX_32_H */
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 86281ffb96d6..a531f6564ed0 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -74,10 +74,6 @@ int acpi_fix_pin2_polarity __initdata;
static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
#endif
-#ifndef __HAVE_ARCH_CMPXCHG
-#warning ACPI uses CMPXCHG, i486 and later hardware
-#endif
-
/* --------------------------------------------------------------------------
Boot-time Configuration
-------------------------------------------------------------------------- */
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index fc605941b9b8..28477b9ac6a9 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -73,7 +73,7 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
* We can speed up the acquire/release, if the architecture
* supports cmpxchg and if there's no debugging state to be set up
*/
-#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
+#ifndef CONFIG_DEBUG_RT_MUTEXES
# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c)
static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
{
--
2.0.0
--
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