diff options
| -rw-r--r-- | arch/parisc/Kconfig | 1 | ||||
| -rw-r--r-- | arch/parisc/include/asm/atomic.h | 23 |
2 files changed, 24 insertions, 0 deletions
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index 433e75a2ee9..fe4afb0f152 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -13,6 +13,7 @@ config PARISC select BUG select HAVE_PERF_EVENTS select GENERIC_ATOMIC64 if !64BIT + select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE select HAVE_GENERIC_HARDIRQS select BROKEN_RODATA select GENERIC_IRQ_PROBE diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h index f38e1984b24..472886ceab1 100644 --- a/arch/parisc/include/asm/atomic.h +++ b/arch/parisc/include/asm/atomic.h @@ -229,6 +229,29 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0) +/* + * atomic64_dec_if_positive - decrement by 1 if old value positive + * @v: pointer of type atomic_t + * + * The function returns the old value of *v minus 1, even if + * the atomic variable, v, was not decremented. + */ +static inline long atomic64_dec_if_positive(atomic64_t *v) +{ + long c, old, dec; + c = atomic64_read(v); + for (;;) { + dec = c - 1; + if (unlikely(dec < 0)) + break; + old = atomic64_cmpxchg((v), c, dec); + if (likely(old == c)) + break; + c = old; + } + return dec; +} + #endif /* !CONFIG_64BIT */ |