[TCP]: Two fixes to new sacktag code
[TCP]: Two fixes to new sacktag code

1) Skip condition used to be wrong way around which made SACK
processing very broken, missed many blocks because of that.

2) Use highest_sack advancement only if some skbs are already
sacked because otherwise tcp_write_queue_next may move things
too far (occurs mainly with GSO). The other similar advancement
is not problem because highest_sack was previosly put to point
a sacked skb.

These problems were located because of problem report from Matt
Mathis <mathis@psc.edu>.

Signed-off-by: Ilpo Järvinen <5801dcaebe162b451612454667e6a167cf0222c1@helsinki.fi>
Signed-off-by: Herbert Xu <ef65de1c7be0aa837fe7b25ba9a7739905af6a55@gondor.apana.org.au>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas