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From: Doug Ledford <dledford@redhat.com>
To: Bart Van Assche <bvanassche@acm.org>,
	Steve Wise <larrystevenwise@gmail.com>,
	linux-rdma@vger.kernel.org, 3100102071@zju.edu.cn,
	leon@kernel.org
Subject: Re: [PATCH 2/2] rxe: correctly calculate iCRC for unaligned payloads
Date: Tue, 03 Dec 2019 19:46:47 -0500
Message-ID: <0f8d9087c48e986d08cf85ef8b59bdca25425eaa.camel@redhat.com> (raw)
In-Reply-To: <a0003c88-10f5-c14a-220d-c100fa160163@acm.org>

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On Tue, 2019-12-03 at 08:25 -0800, Bart Van Assche wrote:
> On 12/2/19 6:03 PM, Steve Wise wrote:
> > If RoCE PDUs being sent or received contain pad bytes, then the iCRC
> > is miscalculated resulting PDUs being emitted by RXE with an
> > incorrect
> > iCRC, as well as ingress PDUs being dropped due to erroneously
> > detecting
> > a bad iCRC in the PDU.  The fix is to include the pad bytes, if any,
> > in iCRC computations.
> 
> Should this description mention that this patch breaks compatibility 
> with SoftRoCE drivers that do not include this fix? Do we need a
> kernel 
> module parameter that allows to select either the old or the new
> behavior?

No.  The original soft-RoCE driver was supposed to be compatible with
hardware devices.  Because of this bug, it obviously wasn't.  This is a
bug fix, and we do not need to do anything to be compatible with the
broken behavior.  Instead, it just needs noting that the soft-RoCE
implementation in prior kernels has a known wire format bug that impacts
communications with both fixed versions of the driver and real hardware
devices.

> > CC: bvanassche@acm.org,3100102071@zju.edu.cn,leon@kernel.org
> 
> Should this Cc-line perhaps be converted into three Cc-lines?
> 
> Otherwise this patch looks fine to me.
> 
> Thanks,
> 
> Bart.
> 

-- 
Doug Ledford <dledford@redhat.com>
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  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-03  2:03 [PATCH 1/2] Update mailmap info for Steve Wise Steve Wise
2019-12-03  2:03 ` [PATCH 2/2] rxe: correctly calculate iCRC for unaligned payloads Steve Wise
2019-12-03 16:25   ` Bart Van Assche
2019-12-03 18:32     ` Steve Wise
2019-12-04  0:46     ` Doug Ledford [this message]
2019-12-09 19:07       ` Doug Ledford
2019-12-10  6:54         ` Leon Romanovsky
2019-12-11  4:24           ` Doug Ledford
2019-12-11  5:59             ` Leon Romanovsky

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