This patch improves the previously added virAtomicInt implementation by using gcc-builtins if possible. The needed builtins are available since GCC >= 4.1. At least the 4.0 docs don't mention them. --- src/util/viratomic.h | 95 ++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 79 insertions(+), 16 deletions(-) Index: libvirt-acl/src/util/viratomic.h =================================================================== --- libvirt-acl.orig/src/util/viratomic.h +++ libvirt-acl/src/util/viratomic.h @@ -30,6 +30,29 @@ typedef struct _virAtomicInt virAtomicInt; typedef virAtomicInt *virAtomicIntPtr; +# define __VIR_ATOMIC_USES_LOCK + +# if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 1)) || (__GNUC__ > 4) +# undef __VIR_ATOMIC_USES_LOCK +# endif + +static inline int virAtomicIntInit(virAtomicIntPtr vaip) + ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK; +static inline int virAtomicIntRead(virAtomicIntPtr vaip) + ATTRIBUTE_NONNULL(1); +static inline void virAtomicIntSet(virAtomicIntPtr vaip, int val) + ATTRIBUTE_NONNULL(1); +static inline int virAtomicIntAdd(virAtomicIntPtr vaip, int add) + ATTRIBUTE_NONNULL(1); +static inline int virAtomicIntSub(virAtomicIntPtr vaip, int add) + ATTRIBUTE_NONNULL(1); +static inline int virAtomicIntInc(virAtomicIntPtr vaip) + ATTRIBUTE_NONNULL(1); +static inline int virAtomicIntDec(virAtomicIntPtr vaip) + ATTRIBUTE_NONNULL(1); + +# ifdef __VIR_ATOMIC_USES_LOCK + struct _virAtomicInt { virMutex lock; int value; @@ -42,22 +65,6 @@ virAtomicIntInit(virAtomicIntPtr vaip) return virMutexInit(&vaip->lock); } -static inline void -virAtomicIntSet(virAtomicIntPtr vaip, int value) -{ - virMutexLock(&vaip->lock); - - vaip->value = value; - - virMutexUnlock(&vaip->lock); -} - -static inline int -virAtomicIntRead(virAtomicIntPtr vaip) -{ - return vaip->value; -} - static inline int virAtomicIntAdd(virAtomicIntPtr vaip, int add) { @@ -88,4 +95,60 @@ virAtomicIntSub(virAtomicIntPtr vaip, in return ret; } +# else /* __VIR_ATOMIC_USES_LOCK */ + +struct _virAtomicInt { + int value; +}; + +static inline int +virAtomicIntInit(virAtomicIntPtr vaip) +{ + vaip->value = 0; + return 0; +} + +static inline int +virAtomicIntAdd(virAtomicIntPtr vaip, int add) +{ + return __sync_add_and_fetch(&vaip->value, add); +} + +static inline int +virAtomicIntSub(virAtomicIntPtr vaip, int sub) +{ + return __sync_sub_and_fetch(&vaip->value, sub); +} + +# endif /* __VIR_ATOMIC_USES_LOCK */ + + + +/* common operations that need no locking or build on others */ + + +static inline void +virAtomicIntSet(virAtomicIntPtr vaip, int value) +{ + vaip->value = value; +} + +static inline int +virAtomicIntRead(virAtomicIntPtr vaip) +{ + return *(volatile int *)&vaip->value; +} + +static inline int +virAtomicIntInc(virAtomicIntPtr vaip) +{ + return virAtomicIntAdd(vaip, 1); +} + +static inline int +virAtomicIntDec(virAtomicIntPtr vaip) +{ + return virAtomicIntSub(vaip, 1); +} + #endif /* __VIR_ATOMIC_H */