sched: Simplify the free path some

If we check the root_domain reference count we can see if its been
used or not, use this observation to simplify some of the return
paths.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110407122942.298339503@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -7023,7 +7023,8 @@ static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
 
 	switch (what) {
 	case sa_rootdomain:
-		free_rootdomain(&d->rd->rcu); /* fall through */
+		if (!atomic_read(&d->rd->refcount))
+			free_rootdomain(&d->rd->rcu); /* fall through */
 	case sa_sd:
 		free_percpu(d->sd); /* fall through */
 	case sa_sd_storage:
@@ -7208,7 +7209,7 @@ static int build_sched_domains(const struct cpumask *cpu_map,
 	enum s_alloc alloc_state = sa_none;
 	struct sched_domain *sd;
 	struct s_data d;
-	int i;
+	int i, ret = -ENOMEM;
 
 	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
 	if (alloc_state != sa_rootdomain)
@@ -7261,12 +7262,10 @@ static int build_sched_domains(const struct cpumask *cpu_map,
 	}
 	rcu_read_unlock();
 
-	__free_domain_allocs(&d, sa_sd, cpu_map);
-	return 0;
-
+	ret = 0;
 error:
 	__free_domain_allocs(&d, alloc_state, cpu_map);
-	return -ENOMEM;
+	return ret;
 }
 
 static cpumask_var_t *doms_cur;	/* current sched domains */