[PATCH 1/5] scheduler: Create SDTL_SKIP flag to skip topology level

[Tim Chen]

A system admin may not want to use cluster scheduling.  Make changes to
allow cluster topology level to be skipped when building sched domains.

Create SDTL_SKIP bit on the sched_domain_topology_level flag so we can
check if the cluster topology level should be skipped when building
sched domains.

Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
---
 include/linux/sched/topology.h |  1 +
 kernel/sched/topology.c        | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index c07bfa2d80f2..a6ad1e02e57a 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -182,6 +182,7 @@ typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
 typedef int (*sched_domain_flags_f)(void);
 
 #define SDTL_OVERLAP	0x01
+#define SDTL_SKIP	0x02
 
 struct sd_data {
 	struct sched_domain *__percpu *sd;
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index d201a7052a29..ee6b14ad3324 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1652,8 +1652,16 @@ static struct sched_domain_topology_level default_topology[] = {
 static struct sched_domain_topology_level *sched_domain_topology =
 	default_topology;
 
+static struct sched_domain_topology_level *next_tl(struct sched_domain_topology_level *tl)
+{
+	++tl;
+	while (tl->mask && tl->flags & SDTL_SKIP)
+		++tl;
+	return tl;
+}
+
 #define for_each_sd_topology(tl)			\
-	for (tl = sched_domain_topology; tl->mask; tl++)
+	for (tl = sched_domain_topology; tl->mask; tl = next_tl(tl))
 
 void set_sched_topology(struct sched_domain_topology_level *tl)
 {
-- 
2.20.1