Re: IORING_SEND_NOTIF_USER_DATA (was Re: IORING_CQE_F_COPIED)

[Stefan Metzmacher <metze@samba.org>]

Hi Pavel,

>>>> Experimenting with this stuff lets me wish to have a way to
>>>> have a different 'user_data' field for the notif cqe,
>>>> maybe based on a IORING_RECVSEND_ flag, it may make my life
>>>> easier and would avoid some complexity in userspace...
>>>> As I need to handle retry on short writes even with MSG_WAITALL
>>>> as EINTR and other errors could cause them.
>>>>
>>>> What do you think?
>>
>> Any comment on this?
>>
>> IORING_SEND_NOTIF_USER_DATA could let us use
>> notif->cqe.user_data = sqe->addr3;
> 
> I'd rather not use the last available u64, tbh, that was the
> reason for not adding a second user_data in the first place.

As far as I can see io_send_zc_prep has this:

         if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
                 return -EINVAL;

both are u64...

metze