diff options
Diffstat (limited to 'arch/arc/include/asm/cmpxchg.h')
| -rw-r--r-- | arch/arc/include/asm/cmpxchg.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h index 90de5c528da2..44fd531f4d7b 100644 --- a/arch/arc/include/asm/cmpxchg.h +++ b/arch/arc/include/asm/cmpxchg.h @@ -10,6 +10,8 @@ #define __ASM_ARC_CMPXCHG_H #include <linux/types.h> + +#include <asm/barrier.h> #include <asm/smp.h> #ifdef CONFIG_ARC_HAS_LLSC @@ -19,6 +21,12 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new) { unsigned long prev; + /* + * Explicit full memory barrier needed before/after as + * LLOCK/SCOND thmeselves don't provide any such semantics + */ + smp_mb(); + __asm__ __volatile__( "1: llock %0, [%1] \n" " brne %0, %2, 2f \n" @@ -31,6 +39,8 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new) "r"(new) /* can't be "ir". scond can't take LIMM for "b" */ : "cc", "memory"); /* so that gcc knows memory is being written here */ + smp_mb(); + return prev; } @@ -43,6 +53,9 @@ __cmpxchg(volatile void *ptr, unsigned long expected, unsigned long new) int prev; volatile unsigned long *p = ptr; + /* + * spin lock/unlock provide the needed smp_mb() before/after + */ atomic_ops_lock(flags); prev = *p; if (prev == expected) @@ -78,12 +91,16 @@ static inline unsigned long __xchg(unsigned long val, volatile void *ptr, switch (size) { case 4: + smp_mb(); + __asm__ __volatile__( " ex %0, [%1] \n" : "+r"(val) : "r"(ptr) : "memory"); + smp_mb(); + return val; } return __xchg_bad_pointer(); |