[PATCH 0/2] net: replace buggy tcp_optlen, and cleanup

[William Allen Simpson <william.allen.simpson@gmail.com>]

This bugginess was reported in October, November, December, and
January.  I'm requesting some independent review and testing.

The tcp_optlen() function returns a potential *negative* unsigned:

-static inline unsigned int tcp_optlen(const struct sk_buff *skb)
-{
-	return (tcp_hdr(skb)->doff - 5) * 4;
-}
-

This is replaced by tcp_header_len_th() and tcp_option_len_th().

The tcp_optlen() function is used *only* in two drivers, that
also have rather messy coding practices; such as:

-	if ((mss = skb_shinfo(skb)->gso_size)) {
...
-	} else
-		mss = 0;

Or:

-	mss = 0;
-	if ((mss = skb_shinfo(skb)->gso_size) != 0) {

Or:

-			iph->tot_len = htons(mss + ip_tcp_len + tcp_opt_len);
-			hdrlen = ip_tcp_len + tcp_opt_len;

Or mixing word and byte sized variables, without using defined constants
or useful sizeof() to make the code self-documenting:

-			if (tcp_opt_len || (iph->ihl > 5)) {
-				vlan_tag_flags |= ((iph->ihl - 5) +
-						   (tcp_opt_len >> 2)) << 8;
-			}

Stand-alone patch, originally developed for TCPCT.

Signed-off-by: William.Allen.Simpson@gmail.com