netdev - Re: [PATCH iwl-net v1] ice: fix receive buffer size miscalculation

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Message-ID: <e09cddf6-3207-b913-ad51-e283b3ebefa7@intel.com>
Date: Thu, 10 Aug 2023 16:44:58 -0700
From: Jesse Brandeburg <jesse.brandeburg@...el.com>
To: Tony Nguyen <anthony.l.nguyen@...el.com>,
	<intel-wired-lan@...ts.osuosl.org>
CC: <netdev@...r.kernel.org>
Subject: Re: [PATCH iwl-net v1] ice: fix receive buffer size miscalculation

On 8/10/2023 2:33 PM, Tony Nguyen wrote:
> 
> 
> On 8/9/2023 5:23 PM, Jesse Brandeburg wrote:
>> The driver is misconfiguring the hardware for some values of MTU such
>> that
>> it could use multiple descriptors to receive a packet when it could have
>> simply used one.
>>
>> Change the driver to use a round-up instead of the result of a shift, as
>> the shift can truncate the lower bits of the size, and result in the
>> problem noted above. It also aligns this driver with similar code in
>> i40e.
>>
>> The insidiousness of this problem is that everything works with the wrong
>> size, it's just not working as well as it could, as some MTU sizes end up
>> using two or more descriptors, and there is no way to tell that is
>> happening without looking at ice_trace or a bus analyzer.
> 
> This should have a Fixes: ?

Dang, you're correct. I'll send a v2.

Thanks,
Jesse