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>
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 82b75a7..fe3ef39 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -57,12 +57,11 @@
} \
#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 @@
: "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 @@
: "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 @@
} \
#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 @@
: "r" (&v->counter), "r" (i) \
: "cc"); \
\
- smp_mb(); \
- \
return result; \
}
@@ -328,6 +324,9 @@
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 @@
#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 @@
: "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 @@
: "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)
{
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h
index 1692a05..916a274 100644
--- a/arch/arm/include/asm/cmpxchg.h
+++ b/arch/arm/include/asm/cmpxchg.h
@@ -35,7 +35,6 @@
unsigned int tmp;
#endif
- smp_mb();
prefetchw((const void *)ptr);
switch (size) {
@@ -98,12 +97,11 @@
__bad_xchg(ptr, size), ret = 0;
break;
}
- smp_mb();
return ret;
}
-#define xchg(ptr, x) ({ \
+#define xchg_relaxed(ptr, x) ({ \
(__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), \
sizeof(*(ptr))); \
})
@@ -117,6 +115,8 @@
#error "SMP is not supported on this platform"
#endif
+#define xchg xchg_relaxed
+
/*
* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
* them available.
@@ -194,23 +194,11 @@
return oldval;
}
-static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
- unsigned long new, int size)
-{
- unsigned long ret;
-
- smp_mb();
- ret = __cmpxchg(ptr, old, new, size);
- smp_mb();
-
- return ret;
-}
-
-#define cmpxchg(ptr,o,n) ({ \
- (__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
- (unsigned long)(o), \
- (unsigned long)(n), \
- sizeof(*(ptr))); \
+#define cmpxchg_relaxed(ptr,o,n) ({ \
+ (__typeof__(*(ptr)))__cmpxchg((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
})
static inline unsigned long __cmpxchg_local(volatile void *ptr,
@@ -273,25 +261,6 @@
#define cmpxchg64_local(ptr, o, n) cmpxchg64_relaxed((ptr), (o), (n))
-static inline unsigned long long __cmpxchg64_mb(unsigned long long *ptr,
- unsigned long long old,
- unsigned long long new)
-{
- unsigned long long ret;
-
- smp_mb();
- ret = __cmpxchg64(ptr, old, new);
- smp_mb();
-
- return ret;
-}
-
-#define cmpxchg64(ptr, o, n) ({ \
- (__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \
- (unsigned long long)(o), \
- (unsigned long long)(n)); \
-})
-
#endif /* __LINUX_ARM_ARCH__ >= 6 */
#endif /* __ASM_ARM_CMPXCHG_H */
