Date: Wed, 13 Aug 2008 15:08:31 -0700 (PDT)
Message-Id: <20080813.150831.193391799.davem@davemloft.net>
To: rdreier@cisco.com
Cc: rick.jones2@hp.com, jgarzik@pobox.com, swise@opengridcomputing.com,
       divy@chelsio.com, kxie@chelsio.com, netdev@vger.kernel.org,
       open-iscsi@googlegroups.com, michaelc@cs.wisc.edu, daisyc@us.ibm.com,
       wenxiong@us.ibm.com, bhua@us.ibm.com, dm@chelsio.com,
       leedom@chelsio.com, linux-scsi@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 1/1] cxgb3i: cxgb3 iSCSI initiator
From: David Miller <davem@davemloft.net>
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	<ada3al8k3l5.fsf@cisco.com>
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From: Roland Dreier <rdreier@cisco.com>
Date: Wed, 13 Aug 2008 14:27:50 -0700

> I don't see how this could work.  First, it seems that you have to let
> the adapter know which connections are iSCSI connections so that it
> knows when to try and parse iSCSI headers.

It always starts from offset zero for never seen before connections.

> So you're already not totally stateless.

Yes, we are.

> Then, since (AFAIK -- I'm not an expert on iSCSI and
> especially I'm not an expert on what common practice is for current
> implementations) the iSCSI PDUs can start at any offset in the TCP
> stream, I don't see how a stateless adapter can even find the PDU
> headers to parse -- there's not any way that I know of to recognize
> where a PDU boundary is without keeping track of the lengths of all the
> PDUs that go by (ie you need per-connection state).

Like I said, you retain a "flow cache" (say it a million times, "flow
cache") that remembers the current parameters and the buffers
currently assigned to that flow and what offset within those buffers.
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