netlink: Replace rhash_portid with bound

@@ -24,6 +24,7 @@
 
 #include <linux/module.h>
 
+#include <asm/barrier.h>
 #include <linux/capability.h>
 #include <linux/kernel.h>
 #include <linux/init.h>

@@ -1015,7 +1016,7 @@ static inline int netlink_compare(struct rhashtable_compare_arg *arg,
 	const struct netlink_compare_arg *x = arg->key;
 	const struct netlink_sock *nlk = ptr;
 
-	return nlk->rhash_portid != x->portid ||
+	return nlk->portid != x->portid ||
 	       !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
 }
 

@@ -1041,7 +1042,7 @@ static int __netlink_insert(struct netlink_table *table, struct sock *sk)
 {
 	struct netlink_compare_arg arg;
 
-	netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->rhash_portid);
+	netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
 	return rhashtable_lookup_insert_key(&table->hash, &arg,
 					    &nlk_sk(sk)->node,
 					    netlink_rhashtable_params);

@@ -1095,7 +1096,7 @@ static int netlink_insert(struct sock *sk, u32 portid)
 	lock_sock(sk);
 
 	err = -EBUSY;
-	if (nlk_sk(sk)->portid)
+	if (nlk_sk(sk)->bound)
 		goto err;
 
 	err = -ENOMEM;

@@ -1103,7 +1104,7 @@ static int netlink_insert(struct sock *sk, u32 portid)
 	    unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX))
 		goto err;
 
-	nlk_sk(sk)->rhash_portid = portid;
+	nlk_sk(sk)->portid = portid;
 	sock_hold(sk);
 
 	err = __netlink_insert(table, sk);

@@ -1119,7 +1120,11 @@ static int netlink_insert(struct sock *sk, u32 portid)
 		goto err;
 	}
 
-	nlk_sk(sk)->portid = portid;
+	/* rhashtable_insert carries an implicit write memory barrier
+	 * so we don't need an smp_wmb here in order to ensure that
+	 * portid is set before bound.
+	 */
+	nlk_sk(sk)->bound = portid;
 
 err:
 	release_sock(sk);

@@ -1521,9 +1526,11 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 			return err;
 	}
 
-	if (nlk->portid)
+	/* Ensure nlk->portid is up-to-date. */
+	if (smp_load_acquire(&nlk->bound)) {
 		if (nladdr->nl_pid != nlk->portid)
 			return -EINVAL;
+	}
 
 	if (nlk->netlink_bind && groups) {
 		int group;

@@ -1539,7 +1546,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 		}
 	}
 
-	if (!nlk->portid) {
+	if (!nlk->bound) {
 		err = nladdr->nl_pid ?
 			netlink_insert(sk, nladdr->nl_pid) :
 			netlink_autobind(sock);

@@ -1587,7 +1594,7 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
 	    !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
 		return -EPERM;
 
-	if (!nlk->portid)
+	if (!nlk->bound)
 		err = netlink_autobind(sock);
 
 	if (err == 0) {

@@ -2428,7 +2435,8 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 		dst_group = nlk->dst_group;
 	}
 
-	if (!nlk->portid) {
+	/* Ensure nlk->portid is up-to-date. */
+	if (!smp_load_acquire(&nlk->bound)) {
 		err = netlink_autobind(sock);
 		if (err)
 			goto out;

@@ -3257,7 +3265,7 @@ static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
 	const struct netlink_sock *nlk = data;
 	struct netlink_compare_arg arg;
 
-	netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->rhash_portid);
+	netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
 	return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
 }
 

@@ -25,7 +25,6 @@ struct netlink_ring {
 struct netlink_sock {
 	/* struct sock has to be the first member of netlink_sock */
 	struct sock		sk;
-	u32			rhash_portid;
 	u32			portid;
 	u32			dst_portid;
 	u32			dst_group;

@@ -36,6 +35,7 @@ struct netlink_sock {
 	unsigned long		state;
 	size_t			max_recvmsg_len;
 	wait_queue_head_t	wait;
+	bool			bound;
 	bool			cb_running;
 	struct netlink_callback	cb;
 	struct mutex		*cb_mutex;