Re: [PATCH v2 1/2] io_uring/zcrx: add single shot recvzc

[Jens Axboe <axboe@kernel.dk>]

On 2/21/25 6:01 PM, Pavel Begunkov wrote:
> On 2/22/25 00:08, Jens Axboe wrote:
>> Just a few minor drive-by nits.
>>
>>> @@ -1250,6 +1251,12 @@ int io_recvzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>>       zc->ifq = req->ctx->ifq;
>>>       if (!zc->ifq)
>>>           return -EINVAL;
>>> +    zc->len = READ_ONCE(sqe->len);
>>> +    if (zc->len == UINT_MAX)
>>> +        return -EINVAL;
>>> +    /* UINT_MAX means no limit on readlen */
>>> +    if (!zc->len)
>>> +        zc->len = UINT_MAX;
>>
>> Why not just make UINT_MAX allowed, meaning no limit? Would avoid two
>> branches here, and as far as I can tell not really change anything in
>> terms of API niceness.
> 
> I think 0 goes better as a special uapi value. It doesn't alter the
> uapi, and commonly understood as "no limits", which is the opposite
> to the other option, especially since UINT_MAX is not a max value for
> an unlimited request, I'd easily expect it to drive more than 4GB.

Yeah that's certainly better, and as you say also has the same (forced)
semantics for multishot.

-- 
Jens Axboe