3 files changed, 28 insertions, 15 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index d77b346..2197af00 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -61,6 +61,7 @@
 #include <linux/rhashtable.h>
 #include <asm/cacheflush.h>
 #include <linux/hash.h>
+#include <linux/genetlink.h>
 
 #include <net/net_namespace.h>
 #include <net/sock.h>
@@ -1091,6 +1092,8 @@ static void netlink_remove(struct sock *sk)
 		__sk_del_bind_node(sk);
 		netlink_update_listeners(sk);
 	}
+	if (sk->sk_protocol == NETLINK_GENERIC)
+		atomic_inc(&genl_sk_destructing_cnt);
 	netlink_table_ungrab();
 }
 
@@ -1214,6 +1217,20 @@ static int netlink_release(struct socket *sock)
 	 * will be purged.
 	 */
 
+	/* must not acquire netlink_table_lock in any way again before unbind
+	 * and notifying genetlink is done as otherwise it might deadlock
+	 */
+	if (nlk->netlink_unbind) {
+		int i;
+
+		for (i = 0; i < nlk->ngroups; i++)
+			if (test_bit(i, nlk->groups))
+				nlk->netlink_unbind(sock_net(sk), i + 1);
+	}
+	if (sk->sk_protocol == NETLINK_GENERIC &&
+	    atomic_dec_return(&genl_sk_destructing_cnt) == 0)
+		wake_up(&genl_sk_destructing_waitq);
+
 	sock->sk = NULL;
 	wake_up_interruptible_all(&nlk->wait);
 
@@ -1249,13 +1266,6 @@ static int netlink_release(struct socket *sock)
 		netlink_table_ungrab();
 	}
 
-	if (nlk->netlink_unbind) {
-		int i;
-
-		for (i = 0; i < nlk->ngroups; i++)
-			if (test_bit(i, nlk->groups))
-				nlk->netlink_unbind(sock_net(sk), i + 1);
-	}
 	kfree(nlk->groups);
 	nlk->groups = NULL;
 
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index 7518375..8900840 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -2,6 +2,7 @@
 #define _AF_NETLINK_H
 
 #include <linux/rhashtable.h>
+#include <linux/atomic.h>
 #include <net/sock.h>
 
 #define NLGRPSZ(x)	(ALIGN(x, sizeof(unsigned long) * 8) / 8)
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index f52a7d5..2ed5f96 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -23,6 +23,9 @@
 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
 static DECLARE_RWSEM(cb_lock);
 
+atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
+DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
+
 void genl_lock(void)
 {
 	mutex_lock(&genl_mutex);
@@ -435,15 +438,18 @@ int genl_unregister_family(struct genl_family *family)
 
 	genl_lock_all();
 
-	genl_unregister_mc_groups(family);
-
 	list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 		if (family->id != rc->id || strcmp(rc->name, family->name))
 			continue;
 
+		genl_unregister_mc_groups(family);
+
 		list_del(&rc->family_list);
 		family->n_ops = 0;
-		genl_unlock_all();
+		up_write(&cb_lock);
+		wait_event(genl_sk_destructing_waitq,
+			   atomic_read(&genl_sk_destructing_cnt) == 0);
+		genl_unlock();
 
 		kfree(family->attrbuf);
 		genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
@@ -987,7 +993,7 @@ static struct genl_multicast_group genl_ctrl_groups[] = {
 
 static int genl_bind(struct net *net, int group)
 {
-	int i, err = 0;
+	int i, err = -ENOENT;
 
 	down_read(&cb_lock);
 	for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
@@ -1016,7 +1022,6 @@ static int genl_bind(struct net *net, int group)
 static void genl_unbind(struct net *net, int group)
 {
 	int i;
-	bool found = false;
 
 	down_read(&cb_lock);
 	for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
@@ -1029,14 +1034,11 @@ static void genl_unbind(struct net *net, int group)
 
 				if (f->mcast_unbind)
 					f->mcast_unbind(net, fam_grp);
-				found = true;
 				break;
 			}
 		}
 	}
 	up_read(&cb_lock);
-
-	WARN_ON(!found);
 }
 
 static int __net_init genl_pernet_init(struct net *net)