diff options
Diffstat (limited to 'arch/alpha/include/asm/xchg.h')
| -rw-r--r-- | arch/alpha/include/asm/xchg.h | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/arch/alpha/include/asm/xchg.h b/arch/alpha/include/asm/xchg.h index e1facf6fc244..e2b59fac5257 100644 --- a/arch/alpha/include/asm/xchg.h +++ b/arch/alpha/include/asm/xchg.h @@ -12,6 +12,10 @@ * Atomic exchange. * Since it can be used to implement critical sections * it must clobber "memory" (also for interrupts in UP). + * + * The leading and the trailing memory barriers guarantee that these + * operations are fully ordered. + * */ static inline unsigned long @@ -19,6 +23,7 @@ ____xchg(_u8, volatile char *m, unsigned long val) { unsigned long ret, tmp, addr64; + smp_mb(); __asm__ __volatile__( " andnot %4,7,%3\n" " insbl %1,%4,%1\n" @@ -43,6 +48,7 @@ ____xchg(_u16, volatile short *m, unsigned long val) { unsigned long ret, tmp, addr64; + smp_mb(); __asm__ __volatile__( " andnot %4,7,%3\n" " inswl %1,%4,%1\n" @@ -67,6 +73,7 @@ ____xchg(_u32, volatile int *m, unsigned long val) { unsigned long dummy; + smp_mb(); __asm__ __volatile__( "1: ldl_l %0,%4\n" " bis $31,%3,%1\n" @@ -87,6 +94,7 @@ ____xchg(_u64, volatile long *m, unsigned long val) { unsigned long dummy; + smp_mb(); __asm__ __volatile__( "1: ldq_l %0,%4\n" " bis $31,%3,%1\n" @@ -128,9 +136,12 @@ ____xchg(, volatile void *ptr, unsigned long x, int size) * store NEW in MEM. Return the initial value in MEM. Success is * indicated by comparing RETURN with OLD. * - * The memory barrier is placed in SMP unconditionally, in order to - * guarantee that dependency ordering is preserved when a dependency - * is headed by an unsuccessful operation. + * The leading and the trailing memory barriers guarantee that these + * operations are fully ordered. + * + * The trailing memory barrier is placed in SMP unconditionally, in + * order to guarantee that dependency ordering is preserved when a + * dependency is headed by an unsuccessful operation. */ static inline unsigned long @@ -138,6 +149,7 @@ ____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new) { unsigned long prev, tmp, cmp, addr64; + smp_mb(); __asm__ __volatile__( " andnot %5,7,%4\n" " insbl %1,%5,%1\n" @@ -165,6 +177,7 @@ ____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new) { unsigned long prev, tmp, cmp, addr64; + smp_mb(); __asm__ __volatile__( " andnot %5,7,%4\n" " inswl %1,%5,%1\n" @@ -192,6 +205,7 @@ ____cmpxchg(_u32, volatile int *m, int old, int new) { unsigned long prev, cmp; + smp_mb(); __asm__ __volatile__( "1: ldl_l %0,%5\n" " cmpeq %0,%3,%1\n" @@ -215,6 +229,7 @@ ____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new) { unsigned long prev, cmp; + smp_mb(); __asm__ __volatile__( "1: ldq_l %0,%5\n" " cmpeq %0,%3,%1\n" |