netdev - Re: [PATCH net-next 1/2] net: Set sk

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Date:	Wed, 29 Jul 2015 22:02:30 +0200
From:	Thomas Graf <tgraf@...g.ch>
To:	Tom Herbert <tom@...bertland.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Kernel Team <kernel-team@...com>
Subject: Re: [PATCH net-next 1/2] net: Set sk_txhash from a random number

On 07/29/15 at 08:58am, Tom Herbert wrote:
> The salient property of both sk_txhash and skb->hash is that they
> provide a uniform distribution over flows. It is incorrect to assume
> that either of these immutable during the lifetime of a flow, so yes
> this means that packets of a flow may go to different receive queues
> when hashes change. SO_REUSEPORT is a process in the receive path but
> uses ehashfn over the ports. But even with SO_REUSEPORT we provide no
> guarantee that packets of a "flow" will always hit the same socket,
> the hashing is not consistent when new reuseport sockets are added or
> removed-- this is actually a long standing issue with SO_REUSEPORT in
> the TCP case since it is possible to orphan connections in SYN-RECV. I
> believe Eric was working toward fixing that, so maybe in the future we
> can use skb->hash if it is a savings.

Thanks for the explanation. I have no objections to the changes then.
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