From 4be7dd393515615430a4d07ca1ffceaf2a331620 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 18 Apr 2016 01:16:07 +0200 Subject: [PATCH] locking/atomic, arch/hexagon: Implement atomic_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: Richard Kuo Cc: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: linux-hexagon@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/hexagon/include/asm/atomic.h | 33 ++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) diff --git a/arch/hexagon/include/asm/atomic.h b/arch/hexagon/include/asm/atomic.h index 55696c4100d4..07dbb3332b4a 100644 --- a/arch/hexagon/include/asm/atomic.h +++ b/arch/hexagon/include/asm/atomic.h @@ -110,7 +110,7 @@ static inline void atomic_##op(int i, atomic_t *v) \ ); \ } \ -#define ATOMIC_OP_RETURN(op) \ +#define ATOMIC_OP_RETURN(op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ int output; \ @@ -127,16 +127,39 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \ return output; \ } -#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) +#define ATOMIC_FETCH_OP(op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int output, val; \ + \ + __asm__ __volatile__ ( \ + "1: %0 = memw_locked(%2);\n" \ + " %1 = "#op "(%0,%3);\n" \ + " memw_locked(%2,P3)=%1;\n" \ + " if !P3 jump 1b;\n" \ + : "=&r" (output), "=&r" (val) \ + : "r" (&v->counter), "r" (i) \ + : "memory", "p3" \ + ); \ + return output; \ +} + +#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op) ATOMIC_OPS(add) ATOMIC_OPS(sub) -ATOMIC_OP(and) -ATOMIC_OP(or) -ATOMIC_OP(xor) +#undef ATOMIC_OPS +#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(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_RETURN #undef ATOMIC_OP