+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 at intel.com>
-Tony
