[RFC][PATCH 4/7] rbtree, perf: Use new rbtree helpers

[Peter Zijlstra]

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 kernel/events/core.c |  178 +++++++++++++++++++++++----------------------------
 1 file changed, 81 insertions(+), 97 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1581,44 +1581,84 @@ static void perf_event_groups_init(struc
  * Implements complex key that first sorts by CPU and then by virtual index
  * which provides ordering when rotating groups for the same CPU.
  */
-static bool
-perf_event_groups_less(struct perf_event *left, struct perf_event *right)
-{
-	if (left->cpu < right->cpu)
-		return true;
-	if (left->cpu > right->cpu)
-		return false;
+static __always_inline int
+perf_event_groups_cmp(const int left_cpu, const struct cgroup *left_cgroup,
+		      const u64 left_group_index, const struct perf_event *right)
+{
+	if (left_cpu < right->cpu)
+		return -1;
+	if (left_cpu > right->cpu)
+		return 1;
 
 #ifdef CONFIG_CGROUP_PERF
-	if (left->cgrp != right->cgrp) {
-		if (!left->cgrp || !left->cgrp->css.cgroup) {
+	{
+	struct cgroup *right_cgroup = right->cgrp ? right->cgrp->css.cgroup : NULL;
+
+	if (left_cgroup != right_cgroup) {
+		if (!left_cgroup) {
 			/*
 			 * Left has no cgroup but right does, no cgroups come
 			 * first.
 			 */
-			return true;
+			return -1;
 		}
-		if (!right->cgrp || !right->cgrp->css.cgroup) {
+		if (!right->cgroup) {
 			/*
 			 * Right has no cgroup but left does, no cgroups come
 			 * first.
 			 */
-			return false;
+			return 1;
 		}
 		/* Two dissimilar cgroups, order by id. */
-		if (left->cgrp->css.cgroup->kn->id < right->cgrp->css.cgroup->kn->id)
-			return true;
+		if (cgroup_id(left_cgroup) < cgroup_id(right_cgroup))
+			return -1;
 
-		return false;
+		return 1;
+	}
 	}
 #endif
 
-	if (left->group_index < right->group_index)
-		return true;
-	if (left->group_index > right->group_index)
-		return false;
+	if (left_group_index < right->group_index)
+		return -1;
+	if (left_group_index > right->group_index)
+		return 1;
 
-	return false;
+	return 0;
+}
+
+static inline struct cgroup *event_cgroup(struct perf_event *event)
+{
+	struct cgroup *cgroup = NULL;
+
+#ifdef CONFIG_CGROUP_PERF
+	if (event->cgrp)
+		cgroup = event->cgrp->css.cgroup;
+#endif
+
+	return cgroup;
+}
+
+#define __node_2_pe(node) \
+	rb_entry((node), struct perf_event, group_node)
+
+static inline bool __group_less(struct rb_node *a, const struct rb_node *b)
+{
+	struct perf_event *e = __node_2_pe(a);
+	return perf_event_groups_cmp(e->cpu, event_cgroup(e), e->group_index,
+				     __node_2_pe(b)) < 0;
+}
+
+struct __group_key {
+	int cpu;
+	struct cgroup *cgroup;
+};
+
+static inline int __group_cmp(const void *key, const struct rb_node *node)
+{
+	const struct __group_key *a = key;
+	const struct perf_event *b = __node_2_pe(node);
+
+	return perf_event_groups_cmp(a->cpu, a->cgroup, b->group_index, b);
 }
 
 /*
@@ -1630,27 +1670,9 @@ static void
 perf_event_groups_insert(struct perf_event_groups *groups,
 			 struct perf_event *event)
 {
-	struct perf_event *node_event;
-	struct rb_node *parent;
-	struct rb_node **node;
-
 	event->group_index = ++groups->index;
 
-	node = &groups->tree.rb_node;
-	parent = *node;
-
-	while (*node) {
-		parent = *node;
-		node_event = container_of(*node, struct perf_event, group_node);
-
-		if (perf_event_groups_less(event, node_event))
-			node = &parent->rb_left;
-		else
-			node = &parent->rb_right;
-	}
-
-	rb_link_node(&event->group_node, parent, node);
-	rb_insert_color(&event->group_node, &groups->tree);
+	rb_add(&groups->tree, &event->group_node, __group_less);
 }
 
 /*
@@ -1698,45 +1720,17 @@ static struct perf_event *
 perf_event_groups_first(struct perf_event_groups *groups, int cpu,
 			struct cgroup *cgrp)
 {
-	struct perf_event *node_event = NULL, *match = NULL;
-	struct rb_node *node = groups->tree.rb_node;
-#ifdef CONFIG_CGROUP_PERF
-	u64 node_cgrp_id, cgrp_id = 0;
-
-	if (cgrp)
-		cgrp_id = cgrp->kn->id;
-#endif
-
-	while (node) {
-		node_event = container_of(node, struct perf_event, group_node);
+	struct __group_key key = {
+		.cpu = cpu,
+		.cgroup = cgrp,
+	};
+	struct rb_node *node;
+
+	node = rb_find_first(&groups->tree, &key, __group_cmp);
+	if (node)
+		return __node_2_pe(node);
 
-		if (cpu < node_event->cpu) {
-			node = node->rb_left;
-			continue;
-		}
-		if (cpu > node_event->cpu) {
-			node = node->rb_right;
-			continue;
-		}
-#ifdef CONFIG_CGROUP_PERF
-		node_cgrp_id = 0;
-		if (node_event->cgrp && node_event->cgrp->css.cgroup)
-			node_cgrp_id = node_event->cgrp->css.cgroup->kn->id;
-
-		if (cgrp_id < node_cgrp_id) {
-			node = node->rb_left;
-			continue;
-		}
-		if (cgrp_id > node_cgrp_id) {
-			node = node->rb_right;
-			continue;
-		}
-#endif
-		match = node_event;
-		node = node->rb_left;
-	}
-
-	return match;
+	return NULL;
 }
 
 /*
@@ -1745,27 +1739,17 @@ perf_event_groups_first(struct perf_even
 static struct perf_event *
 perf_event_groups_next(struct perf_event *event)
 {
-	struct perf_event *next;
-#ifdef CONFIG_CGROUP_PERF
-	u64 curr_cgrp_id = 0;
-	u64 next_cgrp_id = 0;
-#endif
+	struct __group_key key = {
+		.cpu = event->cpu,
+		.cgroup = event_cgroup(event),
+	};
+	struct rb_node *next;
+
+	next = rb_next_match(&event->group_node, &key, __group_cmp);
+	if (next)
+		return __node_2_pe(next);
 
-	next = rb_entry_safe(rb_next(&event->group_node), typeof(*event), group_node);
-	if (next == NULL || next->cpu != event->cpu)
-		return NULL;
-
-#ifdef CONFIG_CGROUP_PERF
-	if (event->cgrp && event->cgrp->css.cgroup)
-		curr_cgrp_id = event->cgrp->css.cgroup->kn->id;
-
-	if (next->cgrp && next->cgrp->css.cgroup)
-		next_cgrp_id = next->cgrp->css.cgroup->kn->id;
-
-	if (curr_cgrp_id != next_cgrp_id)
-		return NULL;
-#endif
-	return next;
+	return NULL;
 }
 
 /*