[PATCH v3 1/2] ia64: implement atomic64_dec_if_positive

Vineet Gupta
2016-09-12T17:58:27Z

This is based on s390 version and needed to get rid of
CONFIG_ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/ia64/include/asm/atomic.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h
index f565ad376142..65d4bb2b6685 100644
--- a/arch/ia64/include/asm/atomic.h
+++ b/arch/ia64/include/asm/atomic.h
@@ -269,6 +269,22 @@ static __inline__ long atomic64_add_unless(atomic64_t *v, long a, long u)

#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)

+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;
+}
+
/*
* Atomically add I to V and return TRUE if the resulting value is
* negative.
--
2.7.4