1 files changed, 50 insertions, 8 deletions

diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 45c0022b91ce..f96812d71c51 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -67,7 +67,25 @@ struct sched_domain_shared {
 	atomic_t	ref;
 	atomic_t	nr_busy_cpus;
 	int		has_idle_cores;
-	int		nr_idle_scan;
+	union {
+		int	nr_idle_scan;
+		/*
+		 * Used during allocation to claim the sched_domain_shared
+		 * object at multiple levels.
+		 *
+		 * Note: between build and the first periodic LB tick, which
+		 * rewrites the union via update_idle_cpu_scan(), readers of
+		 * nr_idle_scan may observe the transient SD_* flag value as
+		 * the scan bound. The flag bits are small positive integers,
+		 * so the effect is just a slightly relaxed scan bound for one
+		 * window and self-heals on the first tick.
+		 */
+		int	alloc_flags;
+	};
+#ifdef CONFIG_SCHED_CACHE
+	unsigned long	util_avg;
+	unsigned long	capacity;
+#endif
 };
 
 struct sched_domain {
@@ -95,9 +113,16 @@ struct sched_domain {
 	unsigned int newidle_call;
 	unsigned int newidle_success;
 	unsigned int newidle_ratio;
+	u64 newidle_stamp;
 	u64 max_newidle_lb_cost;
 	unsigned long last_decay_max_lb_cost;
 
+#ifdef CONFIG_SCHED_CACHE
+	unsigned int llc_max;
+	unsigned int *llc_counts __counted_by_ptr(llc_max);
+	unsigned long llc_bytes;
+#endif
+
 #ifdef CONFIG_SCHEDSTATS
 	/* sched_balance_rq() stats */
 	unsigned int lb_count[CPU_MAX_IDLE_TYPES];
@@ -141,18 +166,30 @@ struct sched_domain {
 
 	unsigned int span_weight;
 	/*
-	 * Span of all CPUs in this domain.
+	 * See sched_domain_span(), on why flex arrays are broken.
 	 *
-	 * NOTE: this field is variable length. (Allocated dynamically
-	 * by attaching extra space to the end of the structure,
-	 * depending on how many CPUs the kernel has booted up with)
-	 */
 	unsigned long span[];
+	 */
 };
 
 static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
 {
-	return to_cpumask(sd->span);
+	/*
+	 * Turns out that C flexible arrays are fundamentally broken since it
+	 * is allowed for offsetof(*sd, span) < sizeof(*sd), this means that
+	 * structure initialzation *sd = { ... }; which writes every byte
+	 * inside sizeof(*type), will over-write the start of the flexible
+	 * array.
+	 *
+	 * Luckily, the way we allocate sched_domain is by:
+	 *
+	 *   sizeof(*sd) + cpumask_size()
+	 *
+	 * this means that we have sufficient space for the whole flex array
+	 * *outside* of sizeof(*sd). So use that, and avoid using sd->span.
+	 */
+	unsigned long *bitmap = (void *)sd + sizeof(*sd);
+	return to_cpumask(bitmap);
 }
 
 extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
@@ -171,7 +208,6 @@ typedef int (*sched_domain_flags_f)(void);
 
 struct sd_data {
 	struct sched_domain *__percpu *sd;
-	struct sched_domain_shared *__percpu *sds;
 	struct sched_group *__percpu *sg;
 	struct sched_group_capacity *__percpu *sgc;
 };
@@ -244,4 +280,10 @@ static inline int task_node(const struct task_struct *p)
 	return cpu_to_node(task_cpu(p));
 }
 
+#ifdef CONFIG_SCHED_CACHE
+extern void sched_update_llc_bytes(const struct cpumask *cpus);
+#else
+static inline void sched_update_llc_bytes(const struct cpumask *cpus) { }
+#endif
+
 #endif /* _LINUX_SCHED_TOPOLOGY_H */