list_for_each_rcu must die: networking

All uses of list_for_each_rcu() can be profitably replaced by the
easier-to-use list_for_each_entry_rcu().  This patch makes this change for
networking, in preparation for removing the list_for_each_rcu() API
entirely.

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/802/psnap.c

@@ -31,11 +31,9 @@ static struct llc_sap *snap_sap;
  */
 static struct datalink_proto *find_snap_client(unsigned char *desc)
 {
-	struct list_head *entry;
 	struct datalink_proto *proto = NULL, *p;
 
-	list_for_each_rcu(entry, &snap_list) {
-		p = list_entry(entry, struct datalink_proto, node);
+	list_for_each_entry_rcu(p, &snap_list, node) {
 		if (!memcmp(p->type, desc, 5)) {
 			proto = p;
 			break;

net/ipv4/af_inet.c

@@ -264,7 +264,6 @@ static inline int inet_netns_ok(struct net *net, int protocol)
 static int inet_create(struct net *net, struct socket *sock, int protocol)
 {
 	struct sock *sk;
-	struct list_head *p;
 	struct inet_protosw *answer;
 	struct inet_sock *inet;
 	struct proto *answer_prot;
@@ -281,13 +280,12 @@ static int inet_create(struct net *net, struct socket *sock, int protocol)
 	sock->state = SS_UNCONNECTED;
 
 	/* Look for the requested type/protocol pair. */
-	answer = NULL;
 lookup_protocol:
 	err = -ESOCKTNOSUPPORT;
 	rcu_read_lock();
-	list_for_each_rcu(p, &inetsw[sock->type]) {
-		answer = list_entry(p, struct inet_protosw, list);
+	list_for_each_entry_rcu(answer, &inetsw[sock->type], list) {
 
+		err = 0;
 		/* Check the non-wild match. */
 		if (protocol == answer->protocol) {
 			if (protocol != IPPROTO_IP)
@@ -302,10 +300,9 @@ lookup_protocol:
 				break;
 		}
 		err = -EPROTONOSUPPORT;
-		answer = NULL;
 	}
 
-	if (unlikely(answer == NULL)) {
+	if (unlikely(err)) {
 		if (try_loading_module < 2) {
 			rcu_read_unlock();
 			/*

net/ipv6/af_inet6.c

@@ -83,7 +83,6 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol)
 	struct inet_sock *inet;
 	struct ipv6_pinfo *np;
 	struct sock *sk;
-	struct list_head *p;
 	struct inet_protosw *answer;
 	struct proto *answer_prot;
 	unsigned char answer_flags;
@@ -97,13 +96,12 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol)
 		build_ehash_secret();
 
 	/* Look for the requested type/protocol pair. */
-	answer = NULL;
 lookup_protocol:
 	err = -ESOCKTNOSUPPORT;
 	rcu_read_lock();
-	list_for_each_rcu(p, &inetsw6[sock->type]) {
-		answer = list_entry(p, struct inet_protosw, list);
+	list_for_each_entry_rcu(answer, &inetsw6[sock->type], list) {
 
+		err = 0;
 		/* Check the non-wild match. */
 		if (protocol == answer->protocol) {
 			if (protocol != IPPROTO_IP)
@@ -118,10 +116,9 @@ lookup_protocol:
 				break;
 		}
 		err = -EPROTONOSUPPORT;
-		answer = NULL;
 	}
 
-	if (!answer) {
+	if (err) {
 		if (try_loading_module < 2) {
 			rcu_read_unlock();
 			/*