Make code iterating over all sched_groups more straightforward.
Note: There's no point in WARN_ON in init_sched_groups_capacity() if
we're going to unconditionally dereference a NULL pointer just a few
instructions later.
Signed-off-by: Michał Mirosław <[email protected]>
---
kernel/sched/fair.c | 13 +++++--------
kernel/sched/sched.h | 5 +++++
kernel/sched/topology.c | 19 ++++++-------------
3 files changed, 16 insertions(+), 21 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7ac9f4b1d955..a8a011f24a6d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9566,15 +9566,13 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
* span the current group.
*/
- group = child->groups;
- do {
+ for_each_sched_group(child, group) {
struct sched_group_capacity *sgc = group->sgc;
capacity += sgc->capacity;
min_capacity = min(sgc->min_capacity, min_capacity);
max_capacity = max(sgc->max_capacity, max_capacity);
- group = group->next;
- } while (group != child->groups);
+ }
}
sdg->sgc->capacity = capacity;
@@ -10549,13 +10547,13 @@ static void update_idle_cpu_scan(struct lb_env *env,
static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
{
- struct sched_group *sg = env->sd->groups;
struct sg_lb_stats *local = &sds->local_stat;
struct sg_lb_stats tmp_sgs;
unsigned long sum_util = 0;
+ struct sched_group *sg;
int sg_status = 0;
- do {
+ for_each_sched_group(env->sd, sg) {
struct sg_lb_stats *sgs = &tmp_sgs;
int local_group;
@@ -10586,8 +10584,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
sds->total_capacity += sgs->group_capacity;
sum_util += sgs->group_util;
- sg = sg->next;
- } while (sg != env->sd->groups);
+ }
/*
* Indicate that the child domain of the busiest group prefers tasks
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 2e5a95486a42..88f3cba60b1e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1902,6 +1902,11 @@ struct sched_group {
unsigned long cpumask[];
};
+#define for_each_sched_group(sd, sg) \
+ for ((sg) = NULL; \
+ likely((sg)) ? (sg) != (sd)->groups : ((((sg) = (sd)->groups)), 1); \
+ (void)((((sg) = (sg)->next)) || ({ BUG(); 0; })))
+
static inline struct cpumask *sched_group_span(struct sched_group *sg)
{
return to_cpumask(sg->cpumask);
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 75b1a18783c2..dce29cf28f32 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -758,17 +758,15 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
sd = sd->parent;
destroy_sched_domain(tmp);
if (sd) {
- struct sched_group *sg = sd->groups;
+ struct sched_group *sg;
/*
* sched groups hold the flags of the child sched
* domain for convenience. Clear such flags since
* the child is being destroyed.
*/
- do {
+ for_each_sched_group(sd, sg)
sg->flags = 0;
- sg = sg->next;
- } while (sg != sd->groups);
sd->child = NULL;
}
@@ -1290,12 +1288,10 @@ build_sched_groups(struct sched_domain *sd, int cpu)
*/
static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
{
- struct sched_group *sg = sd->groups;
struct cpumask *mask = sched_domains_tmpmask2;
+ struct sched_group *sg;
- WARN_ON(!sg);
-
- do {
+ for_each_sched_group(sd, sg) {
int cpu, cores = 0, max_cpu = -1;
sg->group_weight = cpumask_weight(sched_group_span(sg));
@@ -1310,7 +1306,7 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
sg->cores = cores;
if (!(sd->flags & SD_ASYM_PACKING))
- goto next;
+ continue;
for_each_cpu(cpu, sched_group_span(sg)) {
if (max_cpu < 0)
@@ -1319,10 +1315,7 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
max_cpu = cpu;
}
sg->asym_prefer_cpu = max_cpu;
-
-next:
- sg = sg->next;
- } while (sg != sd->groups);
+ }
if (cpu != group_balance_cpu(sg))
return;
--
2.39.2