linux-kernel - Re: [PATCH net-next v20 1/1] mctp pcc: Implement MCTP over PCC Transport

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Message-ID: <0fe71acb-b8b5-4d30-93b4-21aedf2152c8@amperemail.onmicrosoft.com>
Date: Sun, 13 Jul 2025 19:50:43 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: "lihuisong (C)" <lihuisong@...wei.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 Sudeep Holla <sudeep.holla@....com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 admiyo@...amperecomputing.com, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>,
 Jeremy Kerr <jk@...econstruct.com.au>, Eric Dumazet <edumazet@...gle.com>,
 Matt Johnston <matt@...econstruct.com.au>, Paolo Abeni <pabeni@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net-next v20 1/1] mctp pcc: Implement MCTP over PCC
 Transport

On 6/3/25 08:03, lihuisong (C) wrote:
>>
>> Once the memcpy_toio completes, the driver will not look at the 
>> packet again.  if the Kernel did change it at this point, it would 
>> not affect the flow.  The send of the packet is checked vi rc 
>> returned from send_data, and it tags the packet as dropped. Is this 
>> not sufficient?
>>
> Yes, it is not enough.
> Once send_data() return success, platform can receive an interrupt，but 
> the processing of the platform has not ended.
> This processing includes handling data and then triggering an 
> interrupt to notify OS. 

This comment caused me to rethink how I was using the PCC mailbox API.  
I realized that it was not actually enforcing the PCC protocol, which 
you identified.  It lead me to rewrite a postion of the PCC Mailbox API, 
and that is in my next patch series.  I would appreciate it if you would 
take a look. I think it addresses this concern, but it might not be 
completely transparent to a reviewer.   I would greatly appreciate if 
you were to look at it and confirm it fixes the issue, or, if I have 
missed something, let me know what you see.