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/net/ipv4/udp_impl.h b/net/ipv4/udp_impl.h
index 9f4a616..aaad650 100644
--- a/net/ipv4/udp_impl.h
+++ b/net/ipv4/udp_impl.h
@@ -11,13 +11,13 @@
 extern int	udp_v4_get_port(struct sock *sk, unsigned short snum);
 
 extern int	udp_setsockopt(struct sock *sk, int level, int optname,
-			       char __user *optval, int optlen);
+			       char __user *optval, unsigned int optlen);
 extern int	udp_getsockopt(struct sock *sk, int level, int optname,
 			       char __user *optval, int __user *optlen);
 
 #ifdef CONFIG_COMPAT
 extern int	compat_udp_setsockopt(struct sock *sk, int level, int optname,
-				      char __user *optval, int optlen);
+				      char __user *optval, unsigned int optlen);
 extern int	compat_udp_getsockopt(struct sock *sk, int level, int optname,
 				      char __user *optval, int __user *optlen);
 #endif