linux-kernel - [PATCH 06/16] tracepoint: use new hashtable implementation

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Message-Id: <1344961490-4068-7-git-send-email-levinsasha928@gmail.com>
Date:	Tue, 14 Aug 2012 18:24:40 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	torvalds@...ux-foundation.org
Cc:	tj@...nel.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	paul.gortmaker@...driver.com, davem@...emloft.net,
	rostedt@...dmis.org, mingo@...e.hu, ebiederm@...ssion.com,
	aarcange@...hat.com, ericvh@...il.com, netdev@...r.kernel.org,
	josh@...htriplett.org, eric.dumazet@...il.com,
	mathieu.desnoyers@...icios.com, axboe@...nel.dk, agk@...hat.com,
	dm-devel@...hat.com, neilb@...e.de, ccaulfie@...hat.com,
	teigland@...hat.com, Trond.Myklebust@...app.com,
	bfields@...ldses.org, fweisbec@...il.com, jesse@...ira.com,
	venkat.x.venkatsubra@...cle.com, ejt@...hat.com,
	snitzer@...hat.com, edumazet@...gle.com, linux-nfs@...r.kernel.org,
	dev@...nvswitch.org, rds-devel@....oracle.com, lw@...fujitsu.com,
	Sasha Levin <levinsasha928@...il.com>
Subject: [PATCH 06/16] tracepoint: use new hashtable implementation

Switch tracepoints to use the new hashtable implementation. This reduces the amount of
generic unrelated code in the tracepoints.

Signed-off-by: Sasha Levin <levinsasha928@...il.com>
---
 kernel/tracepoint.c |   27 +++++++++++----------------
 1 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index d96ba22..854df92 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -26,6 +26,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/static_key.h>
+#include <linux/hashtable.h>
 
 extern struct tracepoint * const __start___tracepoints_ptrs[];
 extern struct tracepoint * const __stop___tracepoints_ptrs[];
@@ -49,8 +50,7 @@ static LIST_HEAD(tracepoint_module_list);
  * Protected by tracepoints_mutex.
  */
 #define TRACEPOINT_HASH_BITS 6
-#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
-static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
+static DEFINE_HASHTABLE(tracepoint_table, TRACEPOINT_HASH_BITS);
 
 /*
  * Note about RCU :
@@ -191,16 +191,15 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
  */
 static struct tracepoint_entry *get_tracepoint(const char *name)
 {
-	struct hlist_head *head;
 	struct hlist_node *node;
 	struct tracepoint_entry *e;
 	u32 hash = jhash(name, strlen(name), 0);
 
-	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
-	hlist_for_each_entry(e, node, head, hlist) {
+	hash_for_each_possible(tracepoint_table, e, node, hlist, hash) {
 		if (!strcmp(name, e->name))
 			return e;
 	}
+
 	return NULL;
 }
 
@@ -210,19 +209,13 @@ static struct tracepoint_entry *get_tracepoint(const char *name)
  */
 static struct tracepoint_entry *add_tracepoint(const char *name)
 {
-	struct hlist_head *head;
-	struct hlist_node *node;
 	struct tracepoint_entry *e;
 	size_t name_len = strlen(name) + 1;
 	u32 hash = jhash(name, name_len-1, 0);
 
-	head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
-	hlist_for_each_entry(e, node, head, hlist) {
-		if (!strcmp(name, e->name)) {
-			printk(KERN_NOTICE
-				"tracepoint %s busy\n", name);
-			return ERR_PTR(-EEXIST);	/* Already there */
-		}
+	if (get_tracepoint(name)) {
+		printk(KERN_NOTICE "tracepoint %s busy\n", name);
+		return ERR_PTR(-EEXIST);	/* Already there */
 	}
 	/*
 	 * Using kmalloc here to allocate a variable length element. Could
@@ -234,7 +227,7 @@ static struct tracepoint_entry *add_tracepoint(const char *name)
 	memcpy(&e->name[0], name, name_len);
 	e->funcs = NULL;
 	e->refcount = 0;
-	hlist_add_head(&e->hlist, head);
+	hash_add(tracepoint_table, &e->hlist, hash);
 	return e;
 }
 
@@ -244,7 +237,7 @@ static struct tracepoint_entry *add_tracepoint(const char *name)
  */
 static inline void remove_tracepoint(struct tracepoint_entry *e)
 {
-	hlist_del(&e->hlist);
+	hash_del(&e->hlist);
 	kfree(e);
 }
 
@@ -722,6 +715,8 @@ struct notifier_block tracepoint_module_nb = {
 
 static int init_tracepoints(void)
 {
+	hash_init(tracepoint_table);
+
 	return register_module_notifier(&tracepoint_module_nb);
 }
 __initcall(init_tracepoints);
-- 
1.7.8.6

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