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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@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2010-04-02 06:19:16 +00:00 committed by David S. Miller
parent 309795f4be
commit e02d494d2c
1 changed files with 42 additions and 36 deletions
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78
net/l2tp/l2tp_core.c
View File

@ -21,6 +21,7 @@
#include <linux/module.h> #include <linux/module.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/list.h> #include <linux/list.h>
#include <linux/rculist.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/kernel.h> #include <linux/kernel.h>
@ -105,9 +106,9 @@ static atomic_t l2tp_session_count;
static unsigned int l2tp_net_id; static unsigned int l2tp_net_id;
struct l2tp_net { struct l2tp_net {
struct list_head l2tp_tunnel_list; 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]; 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) 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 l2tp_session *session;
struct hlist_node *walk; struct hlist_node *walk;
read_lock_bh(&pn->l2tp_session_hlist_lock); rcu_read_lock_bh();
hlist_for_each_entry(session, walk, session_list, global_hlist) { hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
if (session->session_id == session_id) { if (session->session_id == session_id) {
read_unlock_bh(&pn->l2tp_session_hlist_lock); rcu_read_unlock_bh();
return session; return session;
} }
} }
read_unlock_bh(&pn->l2tp_session_hlist_lock); rcu_read_unlock_bh();
return NULL; return NULL;
} }
@ -225,17 +226,17 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
struct hlist_node *walk; struct hlist_node *walk;
struct l2tp_session *session; 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++) { 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)) { if (!strcmp(session->ifname, ifname)) {
read_unlock_bh(&pn->l2tp_session_hlist_lock); rcu_read_unlock_bh();
return session; return session;
} }
} }
} }
read_unlock_bh(&pn->l2tp_session_hlist_lock); rcu_read_unlock_bh();
return NULL; return NULL;
} }
@ -248,14 +249,14 @@ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
struct l2tp_tunnel *tunnel; struct l2tp_tunnel *tunnel;
struct l2tp_net *pn = l2tp_pernet(net); struct l2tp_net *pn = l2tp_pernet(net);
read_lock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_lock_bh();
list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) { list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (tunnel->tunnel_id == tunnel_id) { if (tunnel->tunnel_id == tunnel_id) {
read_unlock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_unlock_bh();
return tunnel; return tunnel;
} }
} }
read_unlock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_unlock_bh();
return NULL; return NULL;
} }
@ -267,15 +268,15 @@ struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
struct l2tp_tunnel *tunnel; struct l2tp_tunnel *tunnel;
int count = 0; int count = 0;
read_lock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_lock_bh();
list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) { list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (++count > nth) { if (++count > nth) {
read_unlock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_unlock_bh();
return tunnel; return tunnel;
} }
} }
read_unlock_bh(&pn->l2tp_tunnel_list_lock); rcu_read_unlock_bh();
return NULL; return NULL;
} }
@ -1167,9 +1168,10 @@ again:
if (tunnel->version != L2TP_HDR_VER_2) { if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
write_lock_bh(&pn->l2tp_session_hlist_lock); spin_lock_bh(&pn->l2tp_session_hlist_lock);
hlist_del_init(&session->global_hlist); hlist_del_init_rcu(&session->global_hlist);
write_unlock_bh(&pn->l2tp_session_hlist_lock); spin_unlock_bh(&pn->l2tp_session_hlist_lock);
synchronize_rcu();
} }
if (session->session_close != NULL) if (session->session_close != NULL)
@ -1206,9 +1208,10 @@ void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
"%s: free...\n", tunnel->name); "%s: free...\n", tunnel->name);
/* Remove from tunnel list */ /* Remove from tunnel list */
write_lock_bh(&pn->l2tp_tunnel_list_lock); spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_del_init(&tunnel->list); list_del_rcu(&tunnel->list);
write_unlock_bh(&pn->l2tp_tunnel_list_lock); spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
synchronize_rcu();
atomic_dec(&l2tp_tunnel_count); atomic_dec(&l2tp_tunnel_count);
kfree(tunnel); 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 */ /* Add tunnel to our list */
INIT_LIST_HEAD(&tunnel->list); INIT_LIST_HEAD(&tunnel->list);
write_lock_bh(&pn->l2tp_tunnel_list_lock); spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_add(&tunnel->list, &pn->l2tp_tunnel_list); list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
write_unlock_bh(&pn->l2tp_tunnel_list_lock); spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
synchronize_rcu();
atomic_inc(&l2tp_tunnel_count); atomic_inc(&l2tp_tunnel_count);
/* Bump the reference count. The tunnel context is deleted /* 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) { if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
write_lock_bh(&pn->l2tp_session_hlist_lock); spin_lock_bh(&pn->l2tp_session_hlist_lock);
hlist_del_init(&session->global_hlist); hlist_del_init_rcu(&session->global_hlist);
write_unlock_bh(&pn->l2tp_session_hlist_lock); spin_unlock_bh(&pn->l2tp_session_hlist_lock);
synchronize_rcu();
} }
if (session->session_id != 0) 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) { if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
write_lock_bh(&pn->l2tp_session_hlist_lock); spin_lock_bh(&pn->l2tp_session_hlist_lock);
hlist_add_head(&session->global_hlist, hlist_add_head_rcu(&session->global_hlist,
l2tp_session_id_hash_2(pn, session_id)); l2tp_session_id_hash_2(pn, session_id));
write_unlock_bh(&pn->l2tp_session_hlist_lock); spin_unlock_bh(&pn->l2tp_session_hlist_lock);
synchronize_rcu();
} }
/* Ignore management session in session count value */ /* Ignore management session in session count value */
@ -1524,12 +1530,12 @@ static __net_init int l2tp_init_net(struct net *net)
return -ENOMEM; return -ENOMEM;
INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 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++) for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
INIT_HLIST_HEAD(&pn->l2tp_session_hlist[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); err = net_assign_generic(net, l2tp_net_id, pn);
if (err) if (err)