can: make struct proto const

can_ioctl is the only reason for struct proto to be non-const.
script/check-patch.pl suggests struct proto be const.

Setting the reference to the common can_ioctl() in all CAN protocols directly
removes the need to make the struct proto writable in af_can.c

Signed-off-by: Kurt Van Dijck <kurt.van.dijck@eia.be>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 702be5a..733d66f 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -95,7 +95,7 @@
  * af_can socket functions
  */
 
-static int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
 	struct sock *sk = sock->sk;
 
@@ -108,6 +108,7 @@
 		return -ENOIOCTLCMD;
 	}
 }
+EXPORT_SYMBOL(can_ioctl);
 
 static void can_sock_destruct(struct sock *sk)
 {
@@ -698,13 +699,9 @@
 		printk(KERN_ERR "can: protocol %d already registered\n",
 		       proto);
 		err = -EBUSY;
-	} else {
+	} else
 		proto_tab[proto] = cp;
 
-		/* use generic ioctl function if not defined by module */
-		if (!cp->ops->ioctl)
-			cp->ops->ioctl = can_ioctl;
-	}
 	spin_unlock(&proto_tab_lock);
 
 	if (err < 0)