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[v3,1/2] ia64: implement atomic64_dec_if_positive

Message ID 1473703083-8625-2-git-send-email-vgupta@synopsys.com
State New
Headers show

Commit Message

Vineet Gupta Sept. 12, 2016, 5:58 p.m. UTC 
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(+)
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Patch

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.