2 files changed, 39 insertions, 18 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 41024c1c49b4..f77c00dddfe1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -110,6 +110,20 @@ extern int sysctl_sched_rt_runtime;
 extern int sched_rr_timeslice;
 
 /*
+ * Asymmetric CPU capacity bits
+ */
+struct asym_cap_data {
+	struct list_head link;
+	struct rcu_head rcu;
+	unsigned long capacity;
+	unsigned long cpus[];
+};
+
+extern struct list_head asym_cap_list;
+
+#define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
+
+/*
  * Helpers for converting nanosecond timing to jiffy resolution
  */
 #define NS_TO_JIFFIES(TIME)	((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 99ea5986038c..44ed3d0812ab 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1330,23 +1330,12 @@ next:
 }
 
 /*
- * Asymmetric CPU capacity bits
- */
-struct asym_cap_data {
-	struct list_head link;
-	unsigned long capacity;
-	unsigned long cpus[];
-};
-
-/*
  * Set of available CPUs grouped by their corresponding capacities
  * Each list entry contains a CPU mask reflecting CPUs that share the same
  * capacity.
  * The lifespan of data is unlimited.
  */
-static LIST_HEAD(asym_cap_list);
-
-#define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
+LIST_HEAD(asym_cap_list);
 
 /*
  * Verify whether there is any CPU capacity asymmetry in a given sched domain.
@@ -1386,21 +1375,39 @@ asym_cpu_capacity_classify(const struct cpumask *sd_span,
 
 }
 
+static void free_asym_cap_entry(struct rcu_head *head)
+{
+	struct asym_cap_data *entry = container_of(head, struct asym_cap_data, rcu);
+	kfree(entry);
+}
+
 static inline void asym_cpu_capacity_update_data(int cpu)
 {
 	unsigned long capacity = arch_scale_cpu_capacity(cpu);
-	struct asym_cap_data *entry = NULL;
+	struct asym_cap_data *insert_entry = NULL;
+	struct asym_cap_data *entry;
 
+	/*
+	 * Search if capacity already exits. If not, track which the entry
+	 * where we should insert to keep the list ordered descendingly.
+	 */
 	list_for_each_entry(entry, &asym_cap_list, link) {
 		if (capacity == entry->capacity)
 			goto done;
+		else if (!insert_entry && capacity > entry->capacity)
+			insert_entry = list_prev_entry(entry, link);
 	}
 
 	entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
 	if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
 		return;
 	entry->capacity = capacity;
-	list_add(&entry->link, &asym_cap_list);
+
+	/* If NULL then the new capacity is the smallest, add last. */
+	if (!insert_entry)
+		list_add_tail_rcu(&entry->link, &asym_cap_list);
+	else
+		list_add_rcu(&entry->link, &insert_entry->link);
 done:
 	__cpumask_set_cpu(cpu, cpu_capacity_span(entry));
 }
@@ -1423,8 +1430,8 @@ static void asym_cpu_capacity_scan(void)
 
 	list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
 		if (cpumask_empty(cpu_capacity_span(entry))) {
-			list_del(&entry->link);
-			kfree(entry);
+			list_del_rcu(&entry->link);
+			call_rcu(&entry->rcu, free_asym_cap_entry);
 		}
 	}
 
@@ -1434,8 +1441,8 @@ static void asym_cpu_capacity_scan(void)
 	 */
 	if (list_is_singular(&asym_cap_list)) {
 		entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
-		list_del(&entry->link);
-		kfree(entry);
+		list_del_rcu(&entry->link);
+		call_rcu(&entry->rcu, free_asym_cap_entry);
 	}
 }