RE: [PATCH v2 1/2] ia64: implement atomic64_dec_if_positive

["Luck, Tony" <tony.luck@xxxxxxxxx>]

+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;
+}

I was about to say "add a cpu_relax()" in the bottom of that loop. But none of the other
atomic ops that spin on a cmpxchg do that ... so:

Acked-by: Tony Luck <tony.luck@xxxxxxxxx>

-Tony
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