net: Make setsockopt() optlen be unsigned.

This provides safety against negative optlen at the type
level instead of depending upon (sometimes non-trivial)
checks against this sprinkled all over the the place, in
each and every implementation.

Based upon work done by Arjan van de Ven and feedback
from Linus Torvalds.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index 5b26a0b..2f47e54 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -381,10 +381,10 @@
 extern void	ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
 extern int	ip_cmsg_send(struct net *net,
 			     struct msghdr *msg, struct ipcm_cookie *ipc);
-extern int	ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval, int optlen);
+extern int	ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen);
 extern int	ip_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen);
 extern int	compat_ip_setsockopt(struct sock *sk, int level,
-			int optname, char __user *optval, int optlen);
+			int optname, char __user *optval, unsigned int optlen);
 extern int	compat_ip_getsockopt(struct sock *sk, int level,
 			int optname, char __user *optval, int __user *optlen);
 extern int	ip_ra_control(struct sock *sk, unsigned char on, void (*destructor)(struct sock *));