Merge branch 'net-packet-data-races'

Eric Dumazet says:

====================
net/packet: annotate data races

KCSAN sent two reports about data races in af_packet.
Nothing serious, but worth fixing.
====================

Signed-off-by: David S. Miller <[email protected]>

Author: davem330

net/packet/af_packet.c

@@ -2683,7 +2683,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
 	}
 	if (likely(saddr == NULL)) {
 		dev	= packet_cached_dev_get(po);
-		proto	= po->num;
+		proto	= READ_ONCE(po->num);
 	} else {
 		err = -EINVAL;
 		if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -2896,7 +2896,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 
 	if (likely(saddr == NULL)) {
 		dev	= packet_cached_dev_get(po);
-		proto	= po->num;
+		proto	= READ_ONCE(po->num);
 	} else {
 		err = -EINVAL;
 		if (msg->msg_namelen < sizeof(struct sockaddr_ll))
@@ -3171,7 +3171,7 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
 			/* prevents packet_notifier() from calling
 			 * register_prot_hook()
 			 */
-			po->num = 0;
+			WRITE_ONCE(po->num, 0);
 			__unregister_prot_hook(sk, true);
 			rcu_read_lock();
 			dev_curr = po->prot_hook.dev;
@@ -3181,17 +3181,17 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
 		}
 
 		BUG_ON(po->running);
-		po->num = proto;
+		WRITE_ONCE(po->num, proto);
 		po->prot_hook.type = proto;
 
 		if (unlikely(unlisted)) {
 			dev_put(dev);
 			po->prot_hook.dev = NULL;
-			po->ifindex = -1;
+			WRITE_ONCE(po->ifindex, -1);
 			packet_cached_dev_reset(po);
 		} else {
 			po->prot_hook.dev = dev;
-			po->ifindex = dev ? dev->ifindex : 0;
+			WRITE_ONCE(po->ifindex, dev ? dev->ifindex : 0);
 			packet_cached_dev_assign(po, dev);
 		}
 	}
@@ -3505,7 +3505,7 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
 	uaddr->sa_family = AF_PACKET;
 	memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data));
 	rcu_read_lock();
-	dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
+	dev = dev_get_by_index_rcu(sock_net(sk), READ_ONCE(pkt_sk(sk)->ifindex));
 	if (dev)
 		strlcpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data));
 	rcu_read_unlock();
@@ -3520,16 +3520,18 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
 	struct sock *sk = sock->sk;
 	struct packet_sock *po = pkt_sk(sk);
 	DECLARE_SOCKADDR(struct sockaddr_ll *, sll, uaddr);
+	int ifindex;
 
 	if (peer)
 		return -EOPNOTSUPP;
 
+	ifindex = READ_ONCE(po->ifindex);
 	sll->sll_family = AF_PACKET;
-	sll->sll_ifindex = po->ifindex;
-	sll->sll_protocol = po->num;
+	sll->sll_ifindex = ifindex;
+	sll->sll_protocol = READ_ONCE(po->num);
 	sll->sll_pkttype = 0;
 	rcu_read_lock();
-	dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
+	dev = dev_get_by_index_rcu(sock_net(sk), ifindex);
 	if (dev) {
 		sll->sll_hatype = dev->type;
 		sll->sll_halen = dev->addr_len;
@@ -4108,7 +4110,7 @@ static int packet_notifier(struct notifier_block *this,
 				}
 				if (msg == NETDEV_UNREGISTER) {
 					packet_cached_dev_reset(po);
-					po->ifindex = -1;
+					WRITE_ONCE(po->ifindex, -1);
 					if (po->prot_hook.dev)
 						dev_put(po->prot_hook.dev);
 					po->prot_hook.dev = NULL;
@@ -4414,7 +4416,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 	was_running = po->running;
 	num = po->num;
 	if (was_running) {
-		po->num = 0;
+		WRITE_ONCE(po->num, 0);
 		__unregister_prot_hook(sk, false);
 	}
 	spin_unlock(&po->bind_lock);
@@ -4449,7 +4451,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 
 	spin_lock(&po->bind_lock);
 	if (was_running) {
-		po->num = num;
+		WRITE_ONCE(po->num, num);
 		register_prot_hook(sk);
 	}
 	spin_unlock(&po->bind_lock);
@@ -4619,8 +4621,8 @@ static int packet_seq_show(struct seq_file *seq, void *v)
 			   s,
 			   refcount_read(&s->sk_refcnt),
 			   s->sk_type,
-			   ntohs(po->num),
-			   po->ifindex,
+			   ntohs(READ_ONCE(po->num)),
+			   READ_ONCE(po->ifindex),
 			   po->running,
 			   atomic_read(&s->sk_rmem_alloc),
 			   from_kuid_munged(seq_user_ns(seq), sock_i_uid(s)),