- /*
- * We have two variants here. The cmpxchg based one is the best one
- * because it never induce a false contention state. It is included
- * here because architectures using the inc/dec algorithms over the
- * xchg ones are much more likely to support cmpxchg natively.
- *
- * If not we fall back to the spinlock based variant - that is
- * just as efficient (and simpler) as a 'destructive' probing of
- * the mutex state would be.
- */
-#ifdef __HAVE_ARCH_CMPXCHG
- if (likely(atomic_cmpxchg(count, 1, 0) == 1)) {
- smp_mb();