From 0ca326de7aa9cb253db9c1a3eb3f0487c8dbf912 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Thu, 6 Aug 2015 17:54:44 +0100
Subject: locking, ARM, atomics: Define our SMP atomics in terms of _relaxed()
operations
By defining our SMP atomics in terms of relaxed operations, we gain
a small reduction in code size and have acquire/release/fence variants
generated automatically by the core code.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman.Long@hp.com
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1438880084-18856-9-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/arm/include/asm/atomic.h | 37 ++++++++++++++++---------------------
1 file changed, 16 insertions(+), 21 deletions(-)
(limited to 'arch/arm/include/asm/atomic.h')
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 82b75a7cb762..fe3ef397f5a4 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -57,12 +57,11 @@ static inline void atomic_##op(int i, atomic_t *v) \
} \
#define ATOMIC_OP_RETURN(op, c_op, asm_op) \
-static inline int atomic_##op##_return(int i, atomic_t *v) \
+static inline int atomic_##op##_return_relaxed(int i, atomic_t *v) \
{ \
unsigned long tmp; \
int result; \
\
- smp_mb(); \
prefetchw(&v->counter); \
\
__asm__ __volatile__("@ atomic_" #op "_return\n" \
@@ -75,17 +74,17 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
: "r" (&v->counter), "Ir" (i) \
: "cc"); \
\
- smp_mb(); \
- \
return result; \
}
-static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
+#define atomic_add_return_relaxed atomic_add_return_relaxed
+#define atomic_sub_return_relaxed atomic_sub_return_relaxed
+
+static inline int atomic_cmpxchg_relaxed(atomic_t *ptr, int old, int new)
{
int oldval;
unsigned long res;
- smp_mb();
prefetchw(&ptr->counter);
do {
@@ -99,10 +98,9 @@ static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
: "cc");
} while (res);
- smp_mb();
-
return oldval;
}
+#define atomic_cmpxchg_relaxed atomic_cmpxchg_relaxed
static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
@@ -297,12 +295,12 @@ static inline void atomic64_##op(long long i, atomic64_t *v) \
} \
#define ATOMIC64_OP_RETURN(op, op1, op2) \
-static inline long long atomic64_##op##_return(long long i, atomic64_t *v) \
+static inline long long \
+atomic64_##op##_return_relaxed(long long i, atomic64_t *v) \
{ \
long long result; \
unsigned long tmp; \
\
- smp_mb(); \
prefetchw(&v->counter); \
\
__asm__ __volatile__("@ atomic64_" #op "_return\n" \
@@ -316,8 +314,6 @@ static inline long long atomic64_##op##_return(long long i, atomic64_t *v) \
: "r" (&v->counter), "r" (i) \
: "cc"); \
\
- smp_mb(); \
- \
return result; \
}
@@ -328,6 +324,9 @@ static inline long long atomic64_##op##_return(long long i, atomic64_t *v) \
ATOMIC64_OPS(add, adds, adc)
ATOMIC64_OPS(sub, subs, sbc)
+#define atomic64_add_return_relaxed atomic64_add_return_relaxed
+#define atomic64_sub_return_relaxed atomic64_sub_return_relaxed
+
#define atomic64_andnot atomic64_andnot
ATOMIC64_OP(and, and, and)
@@ -339,13 +338,12 @@ ATOMIC64_OP(xor, eor, eor)
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP
-static inline long long atomic64_cmpxchg(atomic64_t *ptr, long long old,
- long long new)
+static inline long long
+atomic64_cmpxchg_relaxed(atomic64_t *ptr, long long old, long long new)
{
long long oldval;
unsigned long res;
- smp_mb();
prefetchw(&ptr->counter);
do {
@@ -360,17 +358,15 @@ static inline long long atomic64_cmpxchg(atomic64_t *ptr, long long old,
: "cc");
} while (res);
- smp_mb();
-
return oldval;
}
+#define atomic64_cmpxchg_relaxed atomic64_cmpxchg_relaxed
-static inline long long atomic64_xchg(atomic64_t *ptr, long long new)
+static inline long long atomic64_xchg_relaxed(atomic64_t *ptr, long long new)
{
long long result;
unsigned long tmp;
- smp_mb();
prefetchw(&ptr->counter);
__asm__ __volatile__("@ atomic64_xchg\n"
@@ -382,10 +378,9 @@ static inline long long atomic64_xchg(atomic64_t *ptr, long long new)
: "r" (&ptr->counter), "r" (new)
: "cc");
- smp_mb();
-
return result;
}
+#define atomic64_xchg_relaxed atomic64_xchg_relaxed
static inline long long atomic64_dec_if_positive(atomic64_t *v)
{
--
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