af_key: locking change

Get rid of custom locking that was using wait queue, lock, and atomic
to basically build a queued mutex.  Use RCU for read side.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/key/af_key.c b/net/key/af_key.c
index a20d2fa..da2fe5f 100644 (file)
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -41,9 +41,7 @@ struct netns_pfkey {
        struct hlist_head table;
        atomic_t socks_nr;
 };
-static DECLARE_WAIT_QUEUE_HEAD(pfkey_table_wait);
-static DEFINE_RWLOCK(pfkey_table_lock);
-static atomic_t pfkey_table_users = ATOMIC_INIT(0);
+static DEFINE_MUTEX(pfkey_mutex);
 
 struct pfkey_sock {
        /* struct sock must be the first member of struct pfkey_sock */
@@ -108,50 +106,6 @@ static void pfkey_sock_destruct(struct sock *sk)
        atomic_dec(&net_pfkey->socks_nr);
 }
 
-static void pfkey_table_grab(void)
-{
-       write_lock_bh(&pfkey_table_lock);
-
-       if (atomic_read(&pfkey_table_users)) {
-               DECLARE_WAITQUEUE(wait, current);
-
-               add_wait_queue_exclusive(&pfkey_table_wait, &wait);
-               for(;;) {
-                       set_current_state(TASK_UNINTERRUPTIBLE);
-                       if (atomic_read(&pfkey_table_users) == 0)
-                               break;
-                       write_unlock_bh(&pfkey_table_lock);
-                       schedule();
-                       write_lock_bh(&pfkey_table_lock);
-               }
-
-               __set_current_state(TASK_RUNNING);
-               remove_wait_queue(&pfkey_table_wait, &wait);
-       }
-}
-
-static __inline__ void pfkey_table_ungrab(void)
-{
-       write_unlock_bh(&pfkey_table_lock);
-       wake_up(&pfkey_table_wait);
-}
-
-static __inline__ void pfkey_lock_table(void)
-{
-       /* read_lock() synchronizes us to pfkey_table_grab */
-
-       read_lock(&pfkey_table_lock);
-       atomic_inc(&pfkey_table_users);
-       read_unlock(&pfkey_table_lock);
-}
-
-static __inline__ void pfkey_unlock_table(void)
-{
-       if (atomic_dec_and_test(&pfkey_table_users))
-               wake_up(&pfkey_table_wait);
-}
-
-
 static const struct proto_ops pfkey_ops;
 
 static void pfkey_insert(struct sock *sk)
@@ -159,16 +113,16 @@ static void pfkey_insert(struct sock *sk)
        struct net *net = sock_net(sk);
        struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
 
-       pfkey_table_grab();
-       sk_add_node(sk, &net_pfkey->table);
-       pfkey_table_ungrab();
+       mutex_lock(&pfkey_mutex);
+       sk_add_node_rcu(sk, &net_pfkey->table);
+       mutex_unlock(&pfkey_mutex);
 }
 
 static void pfkey_remove(struct sock *sk)
 {
-       pfkey_table_grab();
-       sk_del_node_init(sk);
-       pfkey_table_ungrab();
+       mutex_lock(&pfkey_mutex);
+       sk_del_node_init_rcu(sk);
+       mutex_unlock(&pfkey_mutex);
 }
 
 static struct proto key_proto = {
@@ -223,6 +177,8 @@ static int pfkey_release(struct socket *sock)
        sock_orphan(sk);
        sock->sk = NULL;
        skb_queue_purge(&sk->sk_write_queue);
+
+       synchronize_rcu();
        sock_put(sk);
 
        return 0;
@@ -277,8 +233,8 @@ static int pfkey_broadcast(struct sk_buff *skb, gfp_t allocation,
        if (!skb)
                return -ENOMEM;
 
-       pfkey_lock_table();
-       sk_for_each(sk, node, &net_pfkey->table) {
+       rcu_read_lock();
+       sk_for_each_rcu(sk, node, &net_pfkey->table) {
                struct pfkey_sock *pfk = pfkey_sk(sk);
                int err2;
 
@@ -309,7 +265,7 @@ static int pfkey_broadcast(struct sk_buff *skb, gfp_t allocation,
                if ((broadcast_flags & BROADCAST_REGISTERED) && err)
                        err = err2;
        }
-       pfkey_unlock_table();
+       rcu_read_unlock();
 
        if (one_sk != NULL)
                err = pfkey_broadcast_one(skb, &skb2, allocation, one_sk);
@@ -3702,8 +3658,8 @@ static void *pfkey_seq_start(struct seq_file *f, loff_t *ppos)
        struct net *net = seq_file_net(f);
        struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
 
-       read_lock(&pfkey_table_lock);
-       return seq_hlist_start_head(&net_pfkey->table, *ppos);
+       rcu_read_lock();
+       return seq_hlist_start_head_rcu(&net_pfkey->table, *ppos);
 }
 
 static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos)
@@ -3711,12 +3667,12 @@ static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos)
        struct net *net = seq_file_net(f);
        struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
 
-       return seq_hlist_next(v, &net_pfkey->table, ppos);
+       return seq_hlist_next_rcu(v, &net_pfkey->table, ppos);
 }
 
 static void pfkey_seq_stop(struct seq_file *f, void *v)
 {
-       read_unlock(&pfkey_table_lock);
+       rcu_read_unlock();
 }
 
 static const struct seq_operations pfkey_seq_ops = {