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Date: Fri, 27 Nov 2009 15:09:16 +0000
From: "Jan Beulich" <JBeulich@...ell.com>
To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc: <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: slightly shorten __ticket_spin_trylock()
Since the callers generally expect a boolean value, there's no need to
zero-extend the outcome of the comparison. It just requires that all of
x86' trylock implementations return bool instead of int.
Signed-off-by: Jan Beulich <jbeulich@...ell.com>
---
arch/x86/include/asm/paravirt.h | 4 ++--
arch/x86/include/asm/paravirt_types.h | 2 +-
arch/x86/include/asm/spinlock.h | 17 ++++++++---------
arch/x86/xen/spinlock.c | 2 +-
4 files changed, 12 insertions(+), 13 deletions(-)
--- linux-2.6.32-rc8/arch/x86/include/asm/paravirt.h
+++ 2.6.32-rc8-x86-spin-trylock-simplify/arch/x86/include/asm/paravirt.h
@@ -753,9 +753,9 @@ static __always_inline void __raw_spin_l
PVOP_VCALL2(pv_lock_ops.spin_lock_flags, lock, flags);
}
-static __always_inline int __raw_spin_trylock(struct raw_spinlock *lock)
+static __always_inline bool __raw_spin_trylock(struct raw_spinlock *lock)
{
- return PVOP_CALL1(int, pv_lock_ops.spin_trylock, lock);
+ return PVOP_CALL1(bool, pv_lock_ops.spin_trylock, lock);
}
static __always_inline void __raw_spin_unlock(struct raw_spinlock *lock)
--- linux-2.6.32-rc8/arch/x86/include/asm/paravirt_types.h
+++ 2.6.32-rc8-x86-spin-trylock-simplify/arch/x86/include/asm/paravirt_types.h
@@ -324,7 +324,7 @@ struct pv_lock_ops {
int (*spin_is_contended)(struct raw_spinlock *lock);
void (*spin_lock)(struct raw_spinlock *lock);
void (*spin_lock_flags)(struct raw_spinlock *lock, unsigned long flags);
- int (*spin_trylock)(struct raw_spinlock *lock);
+ bool (*spin_trylock)(struct raw_spinlock *lock);
void (*spin_unlock)(struct raw_spinlock *lock);
};
--- linux-2.6.32-rc8/arch/x86/include/asm/spinlock.h
+++ 2.6.32-rc8-x86-spin-trylock-simplify/arch/x86/include/asm/spinlock.h
@@ -77,9 +77,10 @@ static __always_inline void __ticket_spi
: "memory", "cc");
}
-static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
+static __always_inline bool __ticket_spin_trylock(raw_spinlock_t *lock)
{
- int tmp, new;
+ int tmp;
+ union { int i; bool b; } new;
asm volatile("movzwl %2, %0\n\t"
"cmpb %h0,%b0\n\t"
@@ -88,12 +89,11 @@ static __always_inline int __ticket_spin
LOCK_PREFIX "cmpxchgw %w1,%2\n\t"
"1:"
"sete %b1\n\t"
- "movzbl %b1,%0\n\t"
: "=&a" (tmp), "=&q" (new), "+m" (lock->slock)
:
: "memory", "cc");
- return tmp;
+ return new.b;
}
static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
@@ -127,10 +127,10 @@ static __always_inline void __ticket_spi
: "memory", "cc");
}
-static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
+static __always_inline bool __ticket_spin_trylock(raw_spinlock_t *lock)
{
int tmp;
- int new;
+ union { int i; bool b; } new;
asm volatile("movl %2,%0\n\t"
"movl %0,%1\n\t"
@@ -141,12 +141,11 @@ static __always_inline int __ticket_spin
LOCK_PREFIX "cmpxchgl %1,%2\n\t"
"1:"
"sete %b1\n\t"
- "movzbl %b1,%0\n\t"
: "=&a" (tmp), "=&q" (new), "+m" (lock->slock)
:
: "memory", "cc");
- return tmp;
+ return new.b;
}
static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
@@ -190,7 +189,7 @@ static __always_inline void __raw_spin_l
__ticket_spin_lock(lock);
}
-static __always_inline int __raw_spin_trylock(raw_spinlock_t *lock)
+static __always_inline bool __raw_spin_trylock(raw_spinlock_t *lock)
{
return __ticket_spin_trylock(lock);
}
--- linux-2.6.32-rc8/arch/x86/xen/spinlock.c
+++ 2.6.32-rc8-x86-spin-trylock-simplify/arch/x86/xen/spinlock.c
@@ -136,7 +136,7 @@ static int xen_spin_is_contended(struct
return xl->spinners != 0;
}
-static int xen_spin_trylock(struct raw_spinlock *lock)
+static bool xen_spin_trylock(struct raw_spinlock *lock)
{
struct xen_spinlock *xl = (struct xen_spinlock *)lock;
u8 old = 1;
--
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