ia64: implement atomic64_dec_if_positive

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

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vineet Gupta <[email protected]>
Reported-by: kbuild test robot <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h
index f565ad3761427afb14625ee612bdb6067c8d28c2..65d4bb2b6685978f708f34aebf4cd2d00ac4681b 100644 (file)
--- 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.