[PATCH] sched: fix constructing the span cpu mask of sched domain

[Hillf Danton]

For a given node, when constructing the cpumask for its sched_domain
to span, if there is no best node available after searching, further
efforts could be saved, based on small change in the return value of
find_next_best_node().

Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
---

--- a/kernel/sched.c	2011-04-27 11:48:50.000000000 +0800
+++ b/kernel/sched.c	2011-05-05 20:44:52.000000000 +0800
@@ -6787,7 +6787,7 @@ init_sched_build_groups(const struct cpu
  */
 static int find_next_best_node(int node, nodemask_t *used_nodes)
 {
-	int i, n, val, min_val, best_node = 0;
+	int i, n, val, min_val, best_node = -1;

 	min_val = INT_MAX;

@@ -6811,7 +6811,8 @@ static int find_next_best_node(int node,
 		}
 	}

-	node_set(best_node, *used_nodes);
+	if (best_node != -1)
+		node_set(best_node, *used_nodes);
 	return best_node;
 }

@@ -6837,7 +6838,8 @@ static void sched_domain_node_span(int n

 	for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
 		int next_node = find_next_best_node(node, &used_nodes);
-
+		if (next_node < 0)
+			break;
 		cpumask_or(span, span, cpumask_of_node(next_node));
 	}
 }
--
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