netdev - Re: [PATCH v12 net-next 12/15] tcp: accecn: AccECN option send control

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Message-ID: <514ca303-149a-4f7e-a473-31051fb7162b@redhat.com>
Date: Wed, 16 Jul 2025 10:33:33 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: "Chia-Yu Chang (Nokia)" <chia-yu.chang@...ia-bell-labs.com>,
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Subject: Re: [PATCH v12 net-next 12/15] tcp: accecn: AccECN option send
 control

On 7/15/25 5:14 PM, Chia-Yu Chang (Nokia) wrote:
>> On 7/4/25 10:53 AM, chia-yu.chang@...ia-bell-labs.com wrote:
>>> @@ -285,9 +297,33 @@ static inline void 
>>> tcp_ecn_received_counters(struct sock *sk,
>>>
>>>               if (len > 0) {
>>>                       u8 minlen = 
>>> tcp_ecnfield_to_accecn_optfield(ecnfield);
>>> +                     u32 oldbytes = tp->received_ecn_bytes[ecnfield - 
>>> + 1];
>>> +
>>>                       tp->received_ecn_bytes[ecnfield - 1] += len;
>>>                       tp->accecn_minlen = max_t(u8, tp->accecn_minlen,
>>>                                                 minlen);
>>> +
>>> +                     /* Demand AccECN option at least every 2^22 bytes to
>>> +                      * avoid overflowing the ECN byte counters.
>>> +                      */
>>> +                     if ((tp->received_ecn_bytes[ecnfield - 1] ^ oldbytes) &
>>> +                         ~((1 << 22) - 1)) {
>>
>> I don't understand the above statement, I don't think it yield the result expected according to the above comment.
> 
> Hi Paolo,
> 
> I was thinking to change it into GENMASK_U32() and comments like below.
> 
> It is intended to send AccECN option at least once per 2^22-byte increase in the counter.

Ok, I see it now. Please mention explicitly the above in the comment and
test just the 22 bit.

/P