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Date: Fri, 02 Apr 2010 17:19:16 +0100
From: James Chapman <jchapman@...alix.com>
To: netdev@...r.kernel.org
Subject: [PATCH net-next-2.6 v4 10/14] l2tp: Convert rwlock to RCU
Reader/write locks are discouraged because they are slower than spin
locks. So this patch converts the rwlocks used in the per_net structs
to rcu.
Signed-off-by: James Chapman <jchapman@...alix.com>
---
net/l2tp/l2tp_core.c | 78 +++++++++++++++++++++++++++-----------------------
1 files changed, 42 insertions(+), 36 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index fbd1f21..473cf2d 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/string.h>
#include <linux/list.h>
+#include <linux/rculist.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
@@ -105,9 +106,9 @@ static atomic_t l2tp_session_count;
static unsigned int l2tp_net_id;
struct l2tp_net {
struct list_head l2tp_tunnel_list;
- rwlock_t l2tp_tunnel_list_lock;
+ spinlock_t l2tp_tunnel_list_lock;
struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
- rwlock_t l2tp_session_hlist_lock;
+ spinlock_t l2tp_session_hlist_lock;
};
static inline struct l2tp_net *l2tp_pernet(struct net *net)
@@ -139,14 +140,14 @@ static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
struct l2tp_session *session;
struct hlist_node *walk;
- read_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_for_each_entry(session, walk, session_list, global_hlist) {
+ rcu_read_lock_bh();
+ hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
if (session->session_id == session_id) {
- read_unlock_bh(&pn->l2tp_session_hlist_lock);
+ rcu_read_unlock_bh();
return session;
}
}
- read_unlock_bh(&pn->l2tp_session_hlist_lock);
+ rcu_read_unlock_bh();
return NULL;
}
@@ -225,17 +226,17 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
struct hlist_node *walk;
struct l2tp_session *session;
- read_lock_bh(&pn->l2tp_session_hlist_lock);
+ rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
- hlist_for_each_entry(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
+ hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
if (!strcmp(session->ifname, ifname)) {
- read_unlock_bh(&pn->l2tp_session_hlist_lock);
+ rcu_read_unlock_bh();
return session;
}
}
}
- read_unlock_bh(&pn->l2tp_session_hlist_lock);
+ rcu_read_unlock_bh();
return NULL;
}
@@ -248,14 +249,14 @@ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
struct l2tp_tunnel *tunnel;
struct l2tp_net *pn = l2tp_pernet(net);
- read_lock_bh(&pn->l2tp_tunnel_list_lock);
- list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
+ rcu_read_lock_bh();
+ list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (tunnel->tunnel_id == tunnel_id) {
- read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ rcu_read_unlock_bh();
return tunnel;
}
}
- read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ rcu_read_unlock_bh();
return NULL;
}
@@ -267,15 +268,15 @@ struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
struct l2tp_tunnel *tunnel;
int count = 0;
- read_lock_bh(&pn->l2tp_tunnel_list_lock);
- list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
+ rcu_read_lock_bh();
+ list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (++count > nth) {
- read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ rcu_read_unlock_bh();
return tunnel;
}
}
- read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ rcu_read_unlock_bh();
return NULL;
}
@@ -1167,9 +1168,10 @@ again:
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
- write_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_del_init(&session->global_hlist);
- write_unlock_bh(&pn->l2tp_session_hlist_lock);
+ spin_lock_bh(&pn->l2tp_session_hlist_lock);
+ hlist_del_init_rcu(&session->global_hlist);
+ spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ synchronize_rcu();
}
if (session->session_close != NULL)
@@ -1206,9 +1208,10 @@ void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
"%s: free...\n", tunnel->name);
/* Remove from tunnel list */
- write_lock_bh(&pn->l2tp_tunnel_list_lock);
- list_del_init(&tunnel->list);
- write_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ spin_lock_bh(&pn->l2tp_tunnel_list_lock);
+ list_del_rcu(&tunnel->list);
+ spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ synchronize_rcu();
atomic_dec(&l2tp_tunnel_count);
kfree(tunnel);
@@ -1310,9 +1313,10 @@ 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);
- write_lock_bh(&pn->l2tp_tunnel_list_lock);
- list_add(&tunnel->list, &pn->l2tp_tunnel_list);
- write_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ spin_lock_bh(&pn->l2tp_tunnel_list_lock);
+ list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
+ spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ synchronize_rcu();
atomic_inc(&l2tp_tunnel_count);
/* Bump the reference count. The tunnel context is deleted
@@ -1370,9 +1374,10 @@ void l2tp_session_free(struct l2tp_session *session)
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
- write_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_del_init(&session->global_hlist);
- write_unlock_bh(&pn->l2tp_session_hlist_lock);
+ spin_lock_bh(&pn->l2tp_session_hlist_lock);
+ hlist_del_init_rcu(&session->global_hlist);
+ spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ synchronize_rcu();
}
if (session->session_id != 0)
@@ -1494,10 +1499,11 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
- write_lock_bh(&pn->l2tp_session_hlist_lock);
- hlist_add_head(&session->global_hlist,
- l2tp_session_id_hash_2(pn, session_id));
- write_unlock_bh(&pn->l2tp_session_hlist_lock);
+ 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);
+ synchronize_rcu();
}
/* Ignore management session in session count value */
@@ -1524,12 +1530,12 @@ static __net_init int l2tp_init_net(struct net *net)
return -ENOMEM;
INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
- rwlock_init(&pn->l2tp_tunnel_list_lock);
+ 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]);
- rwlock_init(&pn->l2tp_session_hlist_lock);
+ spin_lock_init(&pn->l2tp_session_hlist_lock);
err = net_assign_generic(net, l2tp_net_id, pn);
if (err)
--
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