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>

1 files changed, 21 insertions, 24 deletions

diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index b1adafab377c..8c5bfcef92cb 100644
--- 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