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/dccp/dccp.h b/net/dccp/dccp.h
index d6bc473..5ef32c2 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -290,14 +290,14 @@
 extern int	   dccp_getsockopt(struct sock *sk, int level, int optname,
 				   char __user *optval, int __user *optlen);
 extern int	   dccp_setsockopt(struct sock *sk, int level, int optname,
-				   char __user *optval, int optlen);
+				   char __user *optval, unsigned int optlen);
 #ifdef CONFIG_COMPAT
 extern int	   compat_dccp_getsockopt(struct sock *sk,
 				int level, int optname,
 				char __user *optval, int __user *optlen);
 extern int	   compat_dccp_setsockopt(struct sock *sk,
 				int level, int optname,
-				char __user *optval, int optlen);
+				char __user *optval, unsigned int optlen);
 #endif
 extern int	   dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 extern int	   dccp_sendmsg(struct kiocb *iocb, struct sock *sk,