From mboxrd@z Thu Jan  1 00:00:00 1970
From: William Allen Simpson <william.allen.simpson@gmail.com>
Subject: [PATCH 0/2] net: replace buggy tcp_optlen, and cleanup
Date: Wed, 06 Jan 2010 16:18:52 -0500
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Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Michael Chan <mchan@broadcom.com>
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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