From a8bcccaba162632c3963259b8a442c6b490f4c68 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 18 Apr 2016 01:16:03 +0200 Subject: [PATCH] locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() 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) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/atomic.h | 37 +++++++++++++++++++++++++++--- arch/x86/include/asm/atomic64_32.h | 25 +++++++++++++++++--- arch/x86/include/asm/atomic64_64.h | 35 +++++++++++++++++++++++++--- 3 files changed, 88 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index 3e8674288198..73b8463b89e9 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -171,6 +171,16 @@ static __always_inline int atomic_sub_return(int i, atomic_t *v) #define atomic_inc_return(v) (atomic_add_return(1, v)) #define atomic_dec_return(v) (atomic_sub_return(1, v)) +static __always_inline int atomic_fetch_add(int i, atomic_t *v) +{ + return xadd(&v->counter, i); +} + +static __always_inline int atomic_fetch_sub(int i, atomic_t *v) +{ + return xadd(&v->counter, -i); +} + static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new) { return cmpxchg(&v->counter, old, new); @@ -190,10 +200,31 @@ static inline void atomic_##op(int i, atomic_t *v) \ : "memory"); \ } -ATOMIC_OP(and) -ATOMIC_OP(or) -ATOMIC_OP(xor) +#define ATOMIC_FETCH_OP(op, c_op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int old, val = atomic_read(v); \ + for (;;) { \ + old = atomic_cmpxchg(v, val, val c_op i); \ + if (old == val) \ + break; \ + val = old; \ + } \ + return old; \ +} + +#define ATOMIC_OPS(op, c_op) \ + ATOMIC_OP(op) \ + ATOMIC_FETCH_OP(op, c_op) + +#define atomic_fetch_or atomic_fetch_or + +ATOMIC_OPS(and, &) +ATOMIC_OPS(or , |) +ATOMIC_OPS(xor, ^) +#undef ATOMIC_OPS +#undef ATOMIC_FETCH_OP #undef ATOMIC_OP /** diff --git a/arch/x86/include/asm/atomic64_32.h b/arch/x86/include/asm/atomic64_32.h index a984111135b1..71d7705fb303 100644 --- a/arch/x86/include/asm/atomic64_32.h +++ b/arch/x86/include/asm/atomic64_32.h @@ -320,10 +320,29 @@ static inline void atomic64_##op(long long i, atomic64_t *v) \ c = old; \ } -ATOMIC64_OP(and, &) -ATOMIC64_OP(or, |) -ATOMIC64_OP(xor, ^) +#define ATOMIC64_FETCH_OP(op, c_op) \ +static inline long long atomic64_fetch_##op(long long i, atomic64_t *v) \ +{ \ + long long old, c = 0; \ + while ((old = atomic64_cmpxchg(v, c, c c_op i)) != c) \ + c = old; \ + return old; \ +} + +ATOMIC64_FETCH_OP(add, +) + +#define atomic64_fetch_sub(i, v) atomic64_fetch_add(-(i), (v)) + +#define ATOMIC64_OPS(op, c_op) \ + ATOMIC64_OP(op, c_op) \ + ATOMIC64_FETCH_OP(op, c_op) + +ATOMIC64_OPS(and, &) +ATOMIC64_OPS(or, |) +ATOMIC64_OPS(xor, ^) +#undef ATOMIC64_OPS +#undef ATOMIC64_FETCH_OP #undef ATOMIC64_OP #endif /* _ASM_X86_ATOMIC64_32_H */ diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h index 037351022f54..70eed0e14553 100644 --- a/arch/x86/include/asm/atomic64_64.h +++ b/arch/x86/include/asm/atomic64_64.h @@ -158,6 +158,16 @@ static inline long atomic64_sub_return(long i, atomic64_t *v) return atomic64_add_return(-i, v); } +static inline long atomic64_fetch_add(long i, atomic64_t *v) +{ + return xadd(&v->counter, i); +} + +static inline long atomic64_fetch_sub(long i, atomic64_t *v) +{ + return xadd(&v->counter, -i); +} + #define atomic64_inc_return(v) (atomic64_add_return(1, (v))) #define atomic64_dec_return(v) (atomic64_sub_return(1, (v))) @@ -229,10 +239,29 @@ static inline void atomic64_##op(long i, atomic64_t *v) \ : "memory"); \ } -ATOMIC64_OP(and) -ATOMIC64_OP(or) -ATOMIC64_OP(xor) +#define ATOMIC64_FETCH_OP(op, c_op) \ +static inline long atomic64_fetch_##op(long i, atomic64_t *v) \ +{ \ + long old, val = atomic64_read(v); \ + for (;;) { \ + old = atomic64_cmpxchg(v, val, val c_op i); \ + if (old == val) \ + break; \ + val = old; \ + } \ + return old; \ +} + +#define ATOMIC64_OPS(op, c_op) \ + ATOMIC64_OP(op) \ + ATOMIC64_FETCH_OP(op, c_op) + +ATOMIC64_OPS(and, &) +ATOMIC64_OPS(or, |) +ATOMIC64_OPS(xor, ^) +#undef ATOMIC64_OPS +#undef ATOMIC64_FETCH_OP #undef ATOMIC64_OP #endif /* _ASM_X86_ATOMIC64_64_H */ -- 2.20.1