Re: [PATCH v2 2/2] io_uring/timeout: immediate timeout arg

[Jens Axboe <axboe@kernel.dk>]

On 2/27/26 9:17 AM, Stefan Metzmacher wrote:
> Am 27.02.26 um 16:05 schrieb Jens Axboe:
>> On 2/27/26 7:08 AM, Stefan Metzmacher wrote:
>>> Hi Pavel,
>>>
>>>>        if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
>>>>            return -EINVAL;
>>>> @@ -460,10 +461,20 @@ int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>>>                return -EINVAL;
>>>>            if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
>>>>                tr->ltimeout = true;
>>>> -        if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
>>>> +        if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK |
>>>> +                  IORING_TIMEOUT_ABS |
>>>> +                  IORING_TIMEOUT_IMMEDIATE_ARG))
>>>>                return -EINVAL;
>>>> -        if (get_timespec64(&tr->ts, u64_to_user_ptr(READ_ONCE(sqe->addr2))))
>>>> +
>>>> +        arg = READ_ONCE(sqe->addr2);
>>>> +        if (tr->flags & IORING_TIMEOUT_IMMEDIATE_ARG) {
>>>> +            if (tr->flags & IORING_TIMEOUT_ABS)
>>>> +                return -EINVAL;
>>>> +            tr->ts = ns_to_timespec64(arg);
>>>
>>> I'm wondering if there is enough free space in a small sqe to hold a full timespec?
>>> So that there is no restriction for IORING_TIMEOUT_ABS...
>>
>> There's ->addr3 for another 8b value, so yes it should very much be
>> possible. I quite like that idea, it'll then be the same as the regular
>> timeout options, except the values are passed directly in the sqe rather
>> than needing the copy.
> 
> Yes, attr_ptr and attr_type_mask would even be two 8b values together,
> basically the same as 'struct __kernel_timespec', correct?
> 
> So we could even add 'struct __kernel_timespec ts;' to the last
> union of sqe...

Let's just encode it in addr and addr3, I'd prefer not to further
obfuscate the sqe definition! And on the liburing side, you just add an
immediate helper for setting it up like that, done.

-- 
Jens Axboe