[PATCH 10/15] net,l2tp: use new hashtable implementation

From: Sasha Levin
Date: Mon Dec 17 2012 - 10:04:09 EST

Switch l2tp to use the new hashtable implementation. This reduces the amount
of generic unrelated code in l2tp.

This patch depends on d9b482c ("hashtable: introduce a small and naive
hashtable") which was merged in v3.6.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
net/l2tp/l2tp_core.c | 140 +++++++++++++++++++-----------------------------
net/l2tp/l2tp_core.h | 15 ++++--
net/l2tp/l2tp_debugfs.c | 19 +++----
3 files changed, 74 insertions(+), 100 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 1a9f372..0b369e4 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -44,6 +44,7 @@
#include <linux/udp.h>
#include <linux/l2tp.h>
#include <linux/hash.h>
+#include <linux/hashtable.h>
#include <linux/sort.h>
#include <linux/file.h>
#include <linux/nsproxy.h>
@@ -107,8 +108,14 @@ static unsigned int l2tp_net_id;
struct l2tp_net {
struct list_head l2tp_tunnel_list;
spinlock_t l2tp_tunnel_list_lock;
- struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
- spinlock_t l2tp_session_hlist_lock;
+/*
+ * Session hash global list for L2TPv3.
+ * The session_id SHOULD be random according to RFC3931, but several
+ * L2TP implementations use incrementing session_ids. So we do a real
+ * hash on the session_id, rather than a simple bitmask.
+ */
+ DECLARE_HASHTABLE(l2tp_session_hash, L2TP_HASH_BITS_2);
+ spinlock_t l2tp_session_hash_lock;
};

static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
@@ -156,30 +163,17 @@ do { \
#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
#endif

-/* Session hash global list for L2TPv3.
- * The session_id SHOULD be random according to RFC3931, but several
- * L2TP implementations use incrementing session_ids. So we do a real
- * hash on the session_id, rather than a simple bitmask.
- */
-static inline struct hlist_head *
-l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
-{
- return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
-
-}
-
/* Lookup a session by id in the global session list
*/
static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
{
struct l2tp_net *pn = l2tp_pernet(net);
- struct hlist_head *session_list =
- l2tp_session_id_hash_2(pn, session_id);
struct l2tp_session *session;
struct hlist_node *walk;

rcu_read_lock_bh();
- hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
+ hash_for_each_possible_rcu(pn->l2tp_session_hash, session, walk,
+ global_hlist, session_id) {
if (session->session_id == session_id) {
rcu_read_unlock_bh();
return session;
@@ -190,23 +184,10 @@ static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
return NULL;
}

-/* Session hash list.
- * The session_id SHOULD be random according to RFC2661, but several
- * L2TP implementations (Cisco and Microsoft) use incrementing
- * session_ids. So we do a real hash on the session_id, rather than a
- * simple bitmask.
- */
-static inline struct hlist_head *
-l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
-{
- return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
-}
-
/* Lookup a session by id
*/
struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
{
- struct hlist_head *session_list;
struct l2tp_session *session;
struct hlist_node *walk;

@@ -217,15 +198,14 @@ struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunn
if (tunnel == NULL)
return l2tp_session_find_2(net, session_id);

- session_list = l2tp_session_id_hash(tunnel, session_id);
- read_lock_bh(&tunnel->hlist_lock);
- hlist_for_each_entry(session, walk, session_list, hlist) {
+ read_lock_bh(&tunnel->hash_lock);
+ hash_for_each_possible(tunnel->session_hash, session, walk, hlist, session_id) {
if (session->session_id == session_id) {
- read_unlock_bh(&tunnel->hlist_lock);
+ read_unlock_bh(&tunnel->hash_lock);
return session;
}
}
- read_unlock_bh(&tunnel->hlist_lock);
+ read_unlock_bh(&tunnel->hash_lock);

return NULL;
}
@@ -238,17 +218,15 @@ struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
struct l2tp_session *session;
int count = 0;

- read_lock_bh(&tunnel->hlist_lock);
- for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
- hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
- if (++count > nth) {
- read_unlock_bh(&tunnel->hlist_lock);
- return session;
- }
+ read_lock_bh(&tunnel->hash_lock);
+ hash_for_each(tunnel->session_hash, hash, walk, session, hlist) {
+ if (++count > nth) {
+ read_unlock_bh(&tunnel->hash_lock);
+ return session;
}
}

- read_unlock_bh(&tunnel->hlist_lock);
+ read_unlock_bh(&tunnel->hash_lock);

return NULL;
}
@@ -265,12 +243,10 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
struct l2tp_session *session;

rcu_read_lock_bh();
- for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
- hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
- if (!strcmp(session->ifname, ifname)) {
- rcu_read_unlock_bh();
- return session;
- }
+ hash_for_each_rcu(pn->l2tp_session_hash, hash, walk, session, global_hlist) {
+ if (!strcmp(session->ifname, ifname)) {
+ rcu_read_unlock_bh();
+ return session;
}
}

@@ -1272,7 +1248,7 @@ end:
*/
static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
{
- int hash;
+ int hash, found = 0;
struct hlist_node *walk;
struct hlist_node *tmp;
struct l2tp_session *session;
@@ -1282,16 +1258,14 @@ static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
tunnel->name);

- write_lock_bh(&tunnel->hlist_lock);
- for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
-again:
- hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
- session = hlist_entry(walk, struct l2tp_session, hlist);
-
+ write_lock_bh(&tunnel->hash_lock);
+ do {
+ found = 0;
+ hash_for_each_safe(tunnel->session_hash, hash, walk, tmp, session, hlist) {
l2tp_info(session, L2TP_MSG_CONTROL,
"%s: closing session\n", session->name);

- hlist_del_init(&session->hlist);
+ hash_del(&session->hlist);

/* Since we should hold the sock lock while
* doing any unbinding, we need to release the
@@ -1302,14 +1276,14 @@ again:
if (session->ref != NULL)
(*session->ref)(session);

- write_unlock_bh(&tunnel->hlist_lock);
+ write_unlock_bh(&tunnel->hash_lock);

if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

- spin_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_del_init_rcu(&session->global_hlist);
- spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ spin_lock_bh(&pn->l2tp_session_hash_lock);
+ hash_del_rcu(&session->global_hlist);
+ spin_unlock_bh(&pn->l2tp_session_hash_lock);
synchronize_rcu();
}

@@ -1319,17 +1293,17 @@ again:
if (session->deref != NULL)
(*session->deref)(session);

- write_lock_bh(&tunnel->hlist_lock);
+ write_lock_bh(&tunnel->hash_lock);

/* Now restart from the beginning of this hash
* chain. We always remove a session from the
* list so we are guaranteed to make forward
* progress.
*/
- goto again;
+ found = 1;
}
- }
- write_unlock_bh(&tunnel->hlist_lock);
+ } while (found);
+ write_unlock_bh(&tunnel->hash_lock);
}

/* Really kill the tunnel.
@@ -1576,7 +1550,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32

tunnel->magic = L2TP_TUNNEL_MAGIC;
sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
- rwlock_init(&tunnel->hlist_lock);
+ rwlock_init(&tunnel->hash_lock);

/* The net we belong to */
tunnel->l2tp_net = net;
@@ -1613,6 +1587,8 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32

/* Add tunnel to our list */
INIT_LIST_HEAD(&tunnel->list);
+
+ hash_init(tunnel->session_hash);
atomic_inc(&l2tp_tunnel_count);

/* Bump the reference count. The tunnel context is deleted
@@ -1677,17 +1653,17 @@ void l2tp_session_free(struct l2tp_session *session)
BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

/* Delete the session from the hash */
- write_lock_bh(&tunnel->hlist_lock);
- hlist_del_init(&session->hlist);
- write_unlock_bh(&tunnel->hlist_lock);
+ write_lock_bh(&tunnel->hash_lock);
+ hash_del(&session->hlist);
+ write_unlock_bh(&tunnel->hash_lock);

/* Unlink from the global hash if not L2TPv2 */
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

- spin_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_del_init_rcu(&session->global_hlist);
- spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ spin_lock_bh(&pn->l2tp_session_hash_lock);
+ hash_del_rcu(&session->global_hlist);
+ spin_unlock_bh(&pn->l2tp_session_hash_lock);
synchronize_rcu();
}

@@ -1800,19 +1776,17 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
sock_hold(tunnel->sock);

/* Add session to the tunnel's hash list */
- write_lock_bh(&tunnel->hlist_lock);
- hlist_add_head(&session->hlist,
- l2tp_session_id_hash(tunnel, session_id));
- write_unlock_bh(&tunnel->hlist_lock);
+ write_lock_bh(&tunnel->hash_lock);
+ hash_add(tunnel->session_hash, &session->hlist, session_id);
+ write_unlock_bh(&tunnel->hash_lock);

/* And to the global session list if L2TPv3 */
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);

- spin_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_add_head_rcu(&session->global_hlist,
- l2tp_session_id_hash_2(pn, session_id));
- spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ spin_lock_bh(&pn->l2tp_session_hash_lock);
+ hash_add(pn->l2tp_session_hash, &session->global_hlist, session_id);
+ spin_unlock_bh(&pn->l2tp_session_hash_lock);
}

/* Ignore management session in session count value */
@@ -1831,15 +1805,13 @@ EXPORT_SYMBOL_GPL(l2tp_session_create);
static __net_init int l2tp_init_net(struct net *net)
{
struct l2tp_net *pn = net_generic(net, l2tp_net_id);
- int hash;

INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
spin_lock_init(&pn->l2tp_tunnel_list_lock);

- for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
- INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
+ hash_init(pn->l2tp_session_hash);

- spin_lock_init(&pn->l2tp_session_hlist_lock);
+ spin_lock_init(&pn->l2tp_session_hash_lock);

return 0;
}
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 56d583e..fc58c85 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -11,17 +11,17 @@
#ifndef _L2TP_CORE_H_
#define _L2TP_CORE_H_

+#include <linux/hashtable.h>
+
/* Just some random numbers */
#define L2TP_TUNNEL_MAGIC 0x42114DDA
#define L2TP_SESSION_MAGIC 0x0C04EB7D

/* Per tunnel, session hash table size */
#define L2TP_HASH_BITS 4
-#define L2TP_HASH_SIZE (1 << L2TP_HASH_BITS)

/* System-wide, session hash table size */
#define L2TP_HASH_BITS_2 8
-#define L2TP_HASH_SIZE_2 (1 << L2TP_HASH_BITS_2)

/* Debug message categories for the DEBUG socket option */
enum {
@@ -164,8 +164,15 @@ struct l2tp_tunnel_cfg {
struct l2tp_tunnel {
int magic; /* Should be L2TP_TUNNEL_MAGIC */
struct rcu_head rcu;
- rwlock_t hlist_lock; /* protect session_hlist */
- struct hlist_head session_hlist[L2TP_HASH_SIZE];
+ rwlock_t hash_lock; /* protect session_hash */
+/*
+ * Session hash list.
+ * The session_id SHOULD be random according to RFC2661, but several
+ * L2TP implementations (Cisco and Microsoft) use incrementing
+ * session_ids. So we do a real hash on the session_id, rather than a
+ * simple bitmask.
+*/
+ DECLARE_HASHTABLE(session_hash, L2TP_HASH_BITS);
/* hashed list of sessions,
* hashed by id */
u32 tunnel_id;
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index c3813bc..655f1fa 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -105,21 +105,16 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
int session_count = 0;
int hash;
struct hlist_node *walk;
- struct hlist_node *tmp;
+ struct l2tp_session *session;

- read_lock_bh(&tunnel->hlist_lock);
- for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
- hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
- struct l2tp_session *session;
+ read_lock_bh(&tunnel->hash_lock);
+ hash_for_each(tunnel->session_hash, hash, walk, session, hlist) {
+ if (session->session_id == 0)
+ continue;

- session = hlist_entry(walk, struct l2tp_session, hlist);
- if (session->session_id == 0)
- continue;
-
- session_count++;
- }
+ session_count++;
}
- read_unlock_bh(&tunnel->hlist_lock);
+ read_unlock_bh(&tunnel->hash_lock);

seq_printf(m, "\nTUNNEL %u peer %u", tunnel->tunnel_id, tunnel->peer_tunnel_id);
if (tunnel->sock) {
--
1.8.0

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