[DLCI]: Fix tiny race between module unload and sock_ioctl.

This is a narrow pedantry :) but the dlci_ioctl_hook check and call
should not be parted with the mutex lock.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/socket.c

@@ -909,11 +909,10 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 			if (!dlci_ioctl_hook)
 				request_module("dlci");
 
-			if (dlci_ioctl_hook) {
 			mutex_lock(&dlci_ioctl_mutex);
+			if (dlci_ioctl_hook)
 				err = dlci_ioctl_hook(cmd, argp);
 			mutex_unlock(&dlci_ioctl_mutex);
-			}
 			break;
 		default:
 			err = sock->ops->ioctl(sock, cmd, arg);