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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
David S. Miller
parent
309795f4be
commit
e02d494d2c
@ -21,6 +21,7 @@
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/uaccess.h>
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#include <linux/kernel.h>
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@ -105,9 +106,9 @@ static atomic_t l2tp_session_count;
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static unsigned int l2tp_net_id;
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struct l2tp_net {
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struct list_head l2tp_tunnel_list;
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rwlock_t l2tp_tunnel_list_lock;
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spinlock_t l2tp_tunnel_list_lock;
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struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
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rwlock_t l2tp_session_hlist_lock;
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spinlock_t l2tp_session_hlist_lock;
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};
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static inline struct l2tp_net *l2tp_pernet(struct net *net)
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@ -139,14 +140,14 @@ static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
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struct l2tp_session *session;
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struct hlist_node *walk;
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read_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_for_each_entry(session, walk, session_list, global_hlist) {
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rcu_read_lock_bh();
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hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
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if (session->session_id == session_id) {
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read_unlock_bh(&pn->l2tp_session_hlist_lock);
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rcu_read_unlock_bh();
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return session;
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}
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}
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read_unlock_bh(&pn->l2tp_session_hlist_lock);
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rcu_read_unlock_bh();
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return NULL;
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}
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@ -225,17 +226,17 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
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struct hlist_node *walk;
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struct l2tp_session *session;
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read_lock_bh(&pn->l2tp_session_hlist_lock);
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rcu_read_lock_bh();
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for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
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hlist_for_each_entry(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
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hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
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if (!strcmp(session->ifname, ifname)) {
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read_unlock_bh(&pn->l2tp_session_hlist_lock);
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rcu_read_unlock_bh();
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return session;
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}
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}
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}
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read_unlock_bh(&pn->l2tp_session_hlist_lock);
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rcu_read_unlock_bh();
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return NULL;
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}
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@ -248,14 +249,14 @@ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
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struct l2tp_tunnel *tunnel;
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struct l2tp_net *pn = l2tp_pernet(net);
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read_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
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rcu_read_lock_bh();
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list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
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if (tunnel->tunnel_id == tunnel_id) {
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read_unlock_bh(&pn->l2tp_tunnel_list_lock);
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rcu_read_unlock_bh();
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return tunnel;
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}
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}
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read_unlock_bh(&pn->l2tp_tunnel_list_lock);
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rcu_read_unlock_bh();
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return NULL;
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}
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@ -267,15 +268,15 @@ struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
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struct l2tp_tunnel *tunnel;
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int count = 0;
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read_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
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rcu_read_lock_bh();
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list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
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if (++count > nth) {
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read_unlock_bh(&pn->l2tp_tunnel_list_lock);
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rcu_read_unlock_bh();
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return tunnel;
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}
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}
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read_unlock_bh(&pn->l2tp_tunnel_list_lock);
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rcu_read_unlock_bh();
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return NULL;
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}
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@ -1167,9 +1168,10 @@ again:
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if (tunnel->version != L2TP_HDR_VER_2) {
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struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
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write_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_del_init(&session->global_hlist);
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write_unlock_bh(&pn->l2tp_session_hlist_lock);
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spin_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_del_init_rcu(&session->global_hlist);
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spin_unlock_bh(&pn->l2tp_session_hlist_lock);
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synchronize_rcu();
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}
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if (session->session_close != NULL)
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@ -1206,9 +1208,10 @@ void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
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"%s: free...\n", tunnel->name);
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/* Remove from tunnel list */
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write_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_del_init(&tunnel->list);
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write_unlock_bh(&pn->l2tp_tunnel_list_lock);
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spin_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_del_rcu(&tunnel->list);
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spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
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synchronize_rcu();
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atomic_dec(&l2tp_tunnel_count);
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kfree(tunnel);
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@ -1310,9 +1313,10 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
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/* Add tunnel to our list */
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INIT_LIST_HEAD(&tunnel->list);
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write_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_add(&tunnel->list, &pn->l2tp_tunnel_list);
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write_unlock_bh(&pn->l2tp_tunnel_list_lock);
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spin_lock_bh(&pn->l2tp_tunnel_list_lock);
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list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
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spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
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synchronize_rcu();
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atomic_inc(&l2tp_tunnel_count);
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/* Bump the reference count. The tunnel context is deleted
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@ -1370,9 +1374,10 @@ void l2tp_session_free(struct l2tp_session *session)
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if (tunnel->version != L2TP_HDR_VER_2) {
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struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
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write_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_del_init(&session->global_hlist);
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write_unlock_bh(&pn->l2tp_session_hlist_lock);
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spin_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_del_init_rcu(&session->global_hlist);
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spin_unlock_bh(&pn->l2tp_session_hlist_lock);
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synchronize_rcu();
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}
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if (session->session_id != 0)
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@ -1494,10 +1499,11 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
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if (tunnel->version != L2TP_HDR_VER_2) {
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struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
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write_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_add_head(&session->global_hlist,
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l2tp_session_id_hash_2(pn, session_id));
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write_unlock_bh(&pn->l2tp_session_hlist_lock);
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spin_lock_bh(&pn->l2tp_session_hlist_lock);
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hlist_add_head_rcu(&session->global_hlist,
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l2tp_session_id_hash_2(pn, session_id));
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spin_unlock_bh(&pn->l2tp_session_hlist_lock);
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synchronize_rcu();
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}
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/* Ignore management session in session count value */
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@ -1524,12 +1530,12 @@ static __net_init int l2tp_init_net(struct net *net)
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return -ENOMEM;
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INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
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rwlock_init(&pn->l2tp_tunnel_list_lock);
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spin_lock_init(&pn->l2tp_tunnel_list_lock);
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for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
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INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
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rwlock_init(&pn->l2tp_session_hlist_lock);
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spin_lock_init(&pn->l2tp_session_hlist_lock);
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err = net_assign_generic(net, l2tp_net_id, pn);
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if (err)
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