Merge branch 'master' into for-3.19

Pull in to receive 54ef6df3f3f1 ("rcu: Provide counterpart to
rcu_dereference() for non-RCU situations").

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 28 insertions, 14 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 7a186e7..0007b81 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -96,6 +96,14 @@ static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 static int netlink_dump(struct sock *sk);
 static void netlink_skb_destructor(struct sk_buff *skb);
 
+/* nl_table locking explained:
+ * Lookup and traversal are protected with nl_sk_hash_lock or nl_table_lock
+ * combined with an RCU read-side lock. Insertion and removal are protected
+ * with nl_sk_hash_lock while using RCU list modification primitives and may
+ * run in parallel to nl_table_lock protected lookups. Destruction of the
+ * Netlink socket may only occur *after* nl_table_lock has been acquired
+ * either during or after the socket has been removed from the list.
+ */
 DEFINE_RWLOCK(nl_table_lock);
 EXPORT_SYMBOL_GPL(nl_table_lock);
 static atomic_t nl_table_users = ATOMIC_INIT(0);
@@ -109,10 +117,10 @@ EXPORT_SYMBOL_GPL(nl_sk_hash_lock);
 static int lockdep_nl_sk_hash_is_held(void)
 {
 #ifdef CONFIG_LOCKDEP
-	return (debug_locks) ? lockdep_is_held(&nl_sk_hash_lock) : 1;
-#else
-	return 1;
+	if (debug_locks)
+		return lockdep_is_held(&nl_sk_hash_lock) || lockdep_is_held(&nl_table_lock);
 #endif
+	return 1;
 }
 
 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
@@ -1028,11 +1036,13 @@ static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
 	struct netlink_table *table = &nl_table[protocol];
 	struct sock *sk;
 
+	read_lock(&nl_table_lock);
 	rcu_read_lock();
 	sk = __netlink_lookup(table, portid, net);
 	if (sk)
 		sock_hold(sk);
 	rcu_read_unlock();
+	read_unlock(&nl_table_lock);
 
 	return sk;
 }
@@ -1257,9 +1267,6 @@ static int netlink_release(struct socket *sock)
 	}
 	netlink_table_ungrab();
 
-	/* Wait for readers to complete */
-	synchronize_net();
-
 	kfree(nlk->groups);
 	nlk->groups = NULL;
 
@@ -1281,6 +1288,7 @@ static int netlink_autobind(struct socket *sock)
 
 retry:
 	cond_resched();
+	netlink_table_grab();
 	rcu_read_lock();
 	if (__netlink_lookup(table, portid, net)) {
 		/* Bind collision, search negative portid values. */
@@ -1288,9 +1296,11 @@ retry:
 		if (rover > -4097)
 			rover = -4097;
 		rcu_read_unlock();
+		netlink_table_ungrab();
 		goto retry;
 	}
 	rcu_read_unlock();
+	netlink_table_ungrab();
 
 	err = netlink_insert(sk, net, portid);
 	if (err == -EADDRINUSE)
@@ -1430,7 +1440,7 @@ static void netlink_unbind(int group, long unsigned int groups,
 		return;
 
 	for (undo = 0; undo < group; undo++)
-		if (test_bit(group, &groups))
+		if (test_bit(undo, &groups))
 			nlk->netlink_unbind(undo);
 }
 
@@ -1482,7 +1492,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 			netlink_insert(sk, net, nladdr->nl_pid) :
 			netlink_autobind(sock);
 		if (err) {
-			netlink_unbind(nlk->ngroups - 1, groups, nlk);
+			netlink_unbind(nlk->ngroups, groups, nlk);
 			return err;
 		}
 	}
@@ -2499,6 +2509,7 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
 		nl_table[unit].module = module;
 		if (cfg) {
 			nl_table[unit].bind = cfg->bind;
+			nl_table[unit].unbind = cfg->unbind;
 			nl_table[unit].flags = cfg->flags;
 			if (cfg->compare)
 				nl_table[unit].compare = cfg->compare;
@@ -2921,14 +2932,16 @@ static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
 }
 
 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
-	__acquires(RCU)
+	__acquires(nl_table_lock) __acquires(RCU)
 {
+	read_lock(&nl_table_lock);
 	rcu_read_lock();
 	return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
 }
 
 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
+	struct rhashtable *ht;
 	struct netlink_sock *nlk;
 	struct nl_seq_iter *iter;
 	struct net *net;
@@ -2943,19 +2956,19 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	iter = seq->private;
 	nlk = v;
 
-	rht_for_each_entry_rcu(nlk, nlk->node.next, node)
+	i = iter->link;
+	ht = &nl_table[i].hash;
+	rht_for_each_entry(nlk, nlk->node.next, ht, node)
 		if (net_eq(sock_net((struct sock *)nlk), net))
 			return nlk;
 
-	i = iter->link;
 	j = iter->hash_idx + 1;
 
 	do {
-		struct rhashtable *ht = &nl_table[i].hash;
 		const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
 
 		for (; j < tbl->size; j++) {
-			rht_for_each_entry_rcu(nlk, tbl->buckets[j], node) {
+			rht_for_each_entry(nlk, tbl->buckets[j], ht, node) {
 				if (net_eq(sock_net((struct sock *)nlk), net)) {
 					iter->link = i;
 					iter->hash_idx = j;
@@ -2971,9 +2984,10 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 }
 
 static void netlink_seq_stop(struct seq_file *seq, void *v)
-	__releases(RCU)
+	__releases(RCU) __releases(nl_table_lock)
 {
 	rcu_read_unlock();
+	read_unlock(&nl_table_lock);
 }