Phonet: convert bound sockets hash list to RCU

This gets rid of the last spinlock in the Phonet stack proper.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index b1adafa..8c5bfce 100644 (file)
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -52,7 +52,7 @@ static int pn_socket_release(struct socket *sock)
 
 static struct  {
        struct hlist_head hlist[PN_HASHSIZE];
-       spinlock_t lock;
+       struct mutex lock;
 } pnsocks;
 
 void __init pn_sock_init(void)
@@ -61,7 +61,7 @@ void __init pn_sock_init(void)
 
        for (i = 0; i < PN_HASHSIZE; i++)
                INIT_HLIST_HEAD(pnsocks.hlist + i);
-       spin_lock_init(&pnsocks.lock);
+       mutex_init(&pnsocks.lock);
 }
 
 static struct hlist_head *pn_hash_list(u16 obj)
@@ -82,9 +82,8 @@ struct sock *pn_find_sock_by_sa(struct net *net, const struct sockaddr_pn *spn)
        u8 res = spn->spn_resource;
        struct hlist_head *hlist = pn_hash_list(obj);
 
-       spin_lock_bh(&pnsocks.lock);
-
-       sk_for_each(sknode, node, hlist) {
+       rcu_read_lock();
+       sk_for_each_rcu(sknode, node, hlist) {
                struct pn_sock *pn = pn_sk(sknode);
                BUG_ON(!pn->sobject); /* unbound socket */
 
@@ -107,8 +106,7 @@ struct sock *pn_find_sock_by_sa(struct net *net, const struct sockaddr_pn *spn)
                sock_hold(sknode);
                break;
        }
-
-       spin_unlock_bh(&pnsocks.lock);
+       rcu_read_unlock();
 
        return rval;
 }
@@ -119,7 +117,7 @@ void pn_deliver_sock_broadcast(struct net *net, struct sk_buff *skb)
        struct hlist_head *hlist = pnsocks.hlist;
        unsigned h;
 
-       spin_lock(&pnsocks.lock);
+       rcu_read_lock();
        for (h = 0; h < PN_HASHSIZE; h++) {
                struct hlist_node *node;
                struct sock *sknode;
@@ -140,25 +138,26 @@ void pn_deliver_sock_broadcast(struct net *net, struct sk_buff *skb)
                }
                hlist++;
        }
-       spin_unlock(&pnsocks.lock);
+       rcu_read_unlock();
 }
 
 void pn_sock_hash(struct sock *sk)
 {
        struct hlist_head *hlist = pn_hash_list(pn_sk(sk)->sobject);
 
-       spin_lock_bh(&pnsocks.lock);
-       sk_add_node(sk, hlist);
-       spin_unlock_bh(&pnsocks.lock);
+       mutex_lock(&pnsocks.lock);
+       sk_add_node_rcu(sk, hlist);
+       mutex_unlock(&pnsocks.lock);
 }
 EXPORT_SYMBOL(pn_sock_hash);
 
 void pn_sock_unhash(struct sock *sk)
 {
-       spin_lock_bh(&pnsocks.lock);
-       sk_del_node_init(sk);
-       spin_unlock_bh(&pnsocks.lock);
+       mutex_lock(&pnsocks.lock);
+       sk_del_node_init_rcu(sk);
+       mutex_unlock(&pnsocks.lock);
        pn_sock_unbind_all_res(sk);
+       synchronize_rcu();
 }
 EXPORT_SYMBOL(pn_sock_unhash);
 
@@ -548,7 +547,7 @@ static struct sock *pn_sock_get_idx(struct seq_file *seq, loff_t pos)
        unsigned h;
 
        for (h = 0; h < PN_HASHSIZE; h++) {
-               sk_for_each(sknode, node, hlist) {
+               sk_for_each_rcu(sknode, node, hlist) {
                        if (!net_eq(net, sock_net(sknode)))
                                continue;
                        if (!pos)
@@ -572,9 +571,9 @@ static struct sock *pn_sock_get_next(struct seq_file *seq, struct sock *sk)
 }
 
 static void *pn_sock_seq_start(struct seq_file *seq, loff_t *pos)
-       __acquires(pnsocks.lock)
+       __acquires(rcu)
 {
-       spin_lock_bh(&pnsocks.lock);
+       rcu_read_lock();
        return *pos ? pn_sock_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
 }
 
@@ -591,9 +590,9 @@ static void *pn_sock_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 }
 
 static void pn_sock_seq_stop(struct seq_file *seq, void *v)
-       __releases(pnsocks.lock)
+       __releases(rcu)
 {
-       spin_unlock_bh(&pnsocks.lock);
+       rcu_read_unlock();
 }
 
 static int pn_sock_seq_show(struct seq_file *seq, void *v)
@@ -721,13 +720,11 @@ void pn_sock_unbind_all_res(struct sock *sk)
        }
        mutex_unlock(&resource_mutex);
 
-       if (match == 0)
-               return;
-       synchronize_rcu();
        while (match > 0) {
-               sock_put(sk);
+               __sock_put(sk);
                match--;
        }
+       /* Caller is responsible for RCU sync before final sock_put() */
 }
 
 #ifdef CONFIG_PROC_FS