Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/arm/include/asm/atomic.h | 108 ++++++++++++++++++++++++++++++++++++++----
1 file changed, 98 insertions(+), 10 deletions(-)
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -77,8 +77,36 @@ static inline int atomic_##op##_return_r
return result; \
}
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op##_relaxed(int i, atomic_t *v) \
+{ \
+ unsigned long tmp; \
+ int result, val; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic_fetch_" #op "\n" \
+"1: ldrex %0, [%4]\n" \
+" " #asm_op " %1, %0, %5\n" \
+" strex %2, %1, [%4]\n" \
+" teq %2, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "Ir" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
#define atomic_add_return_relaxed atomic_add_return_relaxed
#define atomic_sub_return_relaxed atomic_sub_return_relaxed
+#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
+#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
+
+#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
+#define atomic_fetch_andnot_relaxed atomic_fetch_andnot_relaxed
+#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
+#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
static inline int atomic_cmpxchg_relaxed(atomic_t *ptr, int old, int new)
{
@@ -159,6 +187,20 @@ static inline int atomic_##op##_return(i
return val; \
}
+#define ATOMIC_FETCH_OP(op, c_op, asm_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ int val; \
+ \
+ raw_local_irq_save(flags); \
+ val = v->counter; \
+ v->counter c_op i; \
+ raw_local_irq_restore(flags); \
+ \
+ return val; \
+}
+
static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
{
int ret;
@@ -187,19 +229,28 @@ static inline int __atomic_add_unless(at
#define ATOMIC_OPS(op, c_op, asm_op) \
ATOMIC_OP(op, c_op, asm_op) \
- ATOMIC_OP_RETURN(op, c_op, asm_op)
+ ATOMIC_OP_RETURN(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
ATOMIC_OPS(add, +=, add)
ATOMIC_OPS(sub, -=, sub)
#define atomic_andnot atomic_andnot
-ATOMIC_OP(and, &=, and)
-ATOMIC_OP(andnot, &= ~, bic)
-ATOMIC_OP(or, |=, orr)
-ATOMIC_OP(xor, ^=, eor)
+#define atomic_fetch_or atomic_fetch_or
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op, asm_op) \
+ ATOMIC_OP(op, c_op, asm_op) \
+ ATOMIC_FETCH_OP(op, c_op, asm_op)
+
+ATOMIC_OPS(and, &=, and)
+ATOMIC_OPS(andnot, &= ~, bic)
+ATOMIC_OPS(or, |=, orr)
+ATOMIC_OPS(xor, ^=, eor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
@@ -317,24 +368,61 @@ atomic64_##op##_return_relaxed(long long
return result; \
}
+#define ATOMIC64_FETCH_OP(op, op1, op2) \
+static inline long long \
+atomic64_fetch_##op##_relaxed(long long i, atomic64_t *v) \
+{ \
+ long long result, val; \
+ unsigned long tmp; \
+ \
+ prefetchw(&v->counter); \
+ \
+ __asm__ __volatile__("@ atomic64_fetch_" #op "\n" \
+"1: ldrexd %0, %H0, [%4]\n" \
+" " #op1 " %Q1, %Q0, %Q5\n" \
+" " #op2 " %R1, %R0, %R5\n" \
+" strexd %2, %1, %H0, [%4]\n" \
+" teq %2, #0\n" \
+" bne 1b" \
+ : "=&r" (result), "=&r" (val), "=&r" (tmp), "+Qo" (v->counter) \
+ : "r" (&v->counter), "r" (i) \
+ : "cc"); \
+ \
+ return result; \
+}
+
#define ATOMIC64_OPS(op, op1, op2) \
ATOMIC64_OP(op, op1, op2) \
- ATOMIC64_OP_RETURN(op, op1, op2)
+ ATOMIC64_OP_RETURN(op, op1, op2) \
+ ATOMIC64_FETCH_OP(op, op1, op2)
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_fetch_add_relaxed atomic64_fetch_add_relaxed
+#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed
+
+#undef ATOMIC64_OPS
+#define ATOMIC64_OPS(op, op1, op2) \
+ ATOMIC64_OP(op, op1, op2) \
+ ATOMIC64_FETCH_OP(op, op1, op2)
#define atomic64_andnot atomic64_andnot
-ATOMIC64_OP(and, and, and)
-ATOMIC64_OP(andnot, bic, bic)
-ATOMIC64_OP(or, orr, orr)
-ATOMIC64_OP(xor, eor, eor)
+ATOMIC64_OPS(and, and, and)
+ATOMIC64_OPS(andnot, bic, bic)
+ATOMIC64_OPS(or, orr, orr)
+ATOMIC64_OPS(xor, eor, eor)
+
+#define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed
+#define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot_relaxed
+#define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed
+#define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed
#undef ATOMIC64_OPS
+#undef ATOMIC64_FETCH_OP
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP
--
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