net: Move IP_ROUTER_ALERT out of lock_sock(sk)

ip_ra_control() does not need sk_lock. Who are the another
users of ip_ra_chain? ip_mroute_setsockopt() doesn't take
sk_lock, while parallel IP_ROUTER_ALERT syscalls are
synchronized by ip_ra_lock. So, we may move this command
out of sk_lock.

Signed-off-by: Kirill Tkhai <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/ip_sockglue.c

···
 
 	/* If optlen==0, it is equivalent to val == 0 */
 
+	if (optname == IP_ROUTER_ALERT)
+		return ip_ra_control(sk, val ? 1 : 0, NULL);
 	if (ip_mroute_opt(optname))
 		return ip_mroute_setsockopt(sk, optname, optval, optlen);
 
···
 		if (val != 0 && val != 1)
 			goto e_inval;
 		inet->mc_all = val;
-		break;
-	case IP_ROUTER_ALERT:
-		err = ip_ra_control(sk, val ? 1 : 0, NULL);
 		break;
 
 	case IP_FREEBIND: