diff options
Diffstat (limited to 'sysdeps/i386/bits')
| -rw-r--r-- | sysdeps/i386/bits/atomic.h | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/sysdeps/i386/bits/atomic.h b/sysdeps/i386/bits/atomic.h index d8aa448d7d..27840f9fe3 100644 --- a/sysdeps/i386/bits/atomic.h +++ b/sysdeps/i386/bits/atomic.h @@ -95,17 +95,29 @@ init_has_cmpxchg (void) \ # define __arch_compare_and_exchange_val_16_acq(mem, newval, oldval) \ ({ __typeof (*mem) ret; \ if (__builtin_expect (has_cmpxchg, 1)) \ - __asm __volatile (LOCK_PREFIX "cmpxchgw %w2, %1" \ - : "=a" (ret), "=m" (*mem) \ - : "r" (newval), "m" (*mem), "0" (oldval)); \ + __asm __volatile (LOCK_PREFIX "cmpxchgw %w2, %1" \ + : "=a" (ret), "=m" (*mem) \ + : "r" (newval), "m" (*mem), "0" (oldval)); \ + else \ + { \ + ret = *mem; \ + if (ret == oldval) \ + *mem = (newval); \ + } \ ret; }) # define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \ ({ __typeof (*mem) ret; \ if (__builtin_expect (has_cmpxchg, 1)) \ - __asm __volatile (LOCK_PREFIX "cmpxchgl %2, %1" \ - : "=a" (ret), "=m" (*mem) \ - : "r" (newval), "m" (*mem), "0" (oldval)); \ + __asm __volatile (LOCK_PREFIX "cmpxchgl %2, %1" \ + : "=a" (ret), "=m" (*mem) \ + : "r" (newval), "m" (*mem), "0" (oldval)); \ + else \ + { \ + ret = *mem; \ + if (ret == oldval) \ + *mem = (newval); \ + } \ ret; }) /* XXX We do not really need 64-bit compare-and-exchange. At least |