linux-kernel - [RFC][PATCH 5/7] rbtree, uprobes: Use rbtree helpers

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Message-Id: <20200429153549.252285117@infradead.org>
Date:   Wed, 29 Apr 2020 17:33:03 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     walken@...gle.com, dave@...olabs.net, mingo@...nel.org,
        tglx@...utronix.de, oleg@...hat.com, irogers@...gle.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        peterz@...radead.org
Subject: [RFC][PATCH 5/7] rbtree, uprobes: Use rbtree helpers


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/events/uprobes.c  |   82 ++++++++++++++++++++++-------------------------
 kernel/locking/rtmutex.c |   54 ++++++++++--------------------
 2 files changed, 58 insertions(+), 78 deletions(-)

--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -619,41 +619,56 @@ static void put_uprobe(struct uprobe *up
 	}
 }
 
-static int match_uprobe(struct uprobe *l, struct uprobe *r)
+static __always_inline
+int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset,
+	       const struct uprobe *r)
 {
-	if (l->inode < r->inode)
+	if (l_inode < r->inode)
 		return -1;
 
-	if (l->inode > r->inode)
+	if (l_inode > r->inode)
 		return 1;
 
-	if (l->offset < r->offset)
+	if (l_offset < r->offset)
 		return -1;
 
-	if (l->offset > r->offset)
+	if (l_offset > r->offset)
 		return 1;
 
 	return 0;
 }
 
+#define __node_2_uprobe(node) \
+	rb_entry((node), struct uprobe, rb_node)
+
+struct __uprobe_key {
+	struct inode *inode;
+	loff_t offset;
+};
+
+static inline int __uprobe_cmp_key(const void *key, const struct rb_node *b)
+{
+	const struct __uprobe_key *a = key;
+	return uprobe_cmp(a->inode, a->offset, __node_2_uprobe(b));
+}
+
+static inline int __uprobe_cmp(struct rb_node *a, const struct rb_node *b)
+{
+	struct uprobe *u = __node_2_uprobe(a);
+	return uprobe_cmp(u->inode, u->offset, __node_2_uprobe(b));
+}
+
 static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
 {
-	struct uprobe u = { .inode = inode, .offset = offset };
-	struct rb_node *n = uprobes_tree.rb_node;
-	struct uprobe *uprobe;
-	int match;
+	struct __uprobe_key key = {
+		.inode = inode,
+		.offset = offset,
+	};
+	struct rb_node *node = rb_find(&uprobes_tree, &key, __uprobe_cmp_key);
+
+	if (node)
+		return __node_2_uprobe(node);
 
-	while (n) {
-		uprobe = rb_entry(n, struct uprobe, rb_node);
-		match = match_uprobe(&u, uprobe);
-		if (!match)
-			return get_uprobe(uprobe);
-
-		if (match < 0)
-			n = n->rb_left;
-		else
-			n = n->rb_right;
-	}
 	return NULL;
 }
 
@@ -674,32 +689,15 @@ static struct uprobe *find_uprobe(struct
 
 static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
 {
-	struct rb_node **p = &uprobes_tree.rb_node;
-	struct rb_node *parent = NULL;
-	struct uprobe *u;
-	int match;
-
-	while (*p) {
-		parent = *p;
-		u = rb_entry(parent, struct uprobe, rb_node);
-		match = match_uprobe(uprobe, u);
-		if (!match)
-			return get_uprobe(u);
-
-		if (match < 0)
-			p = &parent->rb_left;
-		else
-			p = &parent->rb_right;
+	struct rb_node *node;
 
-	}
+	node = rb_find_add(&uprobes_tree, &uprobe->rb_node, __uprobe_cmp);
+	if (node)
+		return get_uprobe(__node_2_uprobe(node));
 
-	u = NULL;
-	rb_link_node(&uprobe->rb_node, parent, p);
-	rb_insert_color(&uprobe->rb_node, &uprobes_tree);
 	/* get access + creation ref */
 	refcount_set(&uprobe->ref, 2);
-
-	return u;
+	return NULL;
 }
 
 /*