Re: [PATCH] tcp: make urg+gso work for real this time
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: 2008-12-17 23:26:11
On Wed, Dec 17, 2008 at 03:17:13PM -0800, David Miller wrote:
Also, what if we're using IPV6 jumbo frames and we advertise this special 0xffff URG offset turd? That points to a real byte in the packet, but it might not be the right one since we can only accurately point up to 0xffff into there.
1) We don't support that right now. 2) Even if we did this would be broken either way because just where do you put the urgent pointer if your packet is > 64K and the urgent pointer lies in the packet but beyond 64K to the start? In any case we can easily fix this up with an additional check so I don't think it's central to the issue overall.
Given all of this I still think our current compromise is likely the best one. We never will advertise an URG pointer that is not pointing to where the URG data will be in the sequence space.
I agree to the extent that urgent mode is hopelessly broken in so many ways so one more isn't going to make that much of a difference. However, I still think that the approach suggested by Alexey is better than the status quo: 1) It's unlikely to break any existing apps (all it does is send SIGURG multiple times). 2) For those apps that use urgent mode in the first place, they're likely to want to see the urgent notification ASAP, rather than having it delayed due to the receiver being busy. So this is an improvement over what we have. Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} [off-list ref] Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt