Re: [PATCH v2] signal: add procfd_signal() syscall

[Christian Brauner]

On December 1, 2018 12:46:22 PM GMT+13:00, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>On Fri, Nov 30, 2018 at 3:40 PM Christian Brauner
><christian@xxxxxxxxxx> wrote:
>>
>> On December 1, 2018 12:12:53 PM GMT+13:00, Arnd Bergmann
><arnd@xxxxxxxx> wrote:
>> >On Sat, Dec 1, 2018 at 12:05 AM Daniel Colascione
><dancol@xxxxxxxxxx>
>> >wrote:
>> >> On Fri, Nov 30, 2018 at 2:26 PM Christian Brauner
>> ><christian@xxxxxxxxxx> wrote:
>> >> > On December 1, 2018 11:09:58 AM GMT+13:00, Arnd Bergmann
>> ><arnd@xxxxxxxx> wrote:
>> >> >
>> >> > One humble point I would like to make is that what I care about
>> >most is a sensible way forward without having to redo essential
>parts
>> >of how syscalls work.
>> >> > I don't want to introduce a sane, small syscall that ends up
>> >breaking all over the place because we decided to fix past mistakes
>> >that technically have nothing to do with the patch itself.
>> >> > However, I do sympathize and understand these concerns.
>> >>
>> >> IMHO, it's fine to just replicate all the splits we have for the
>> >> existing signal system calls. It's ugly, but once it's done, it'll
>be
>> >> done for a long time. I can't see a need to add even more signal
>> >> system calls after this one.
>> >
>> >We definitely need waitid_time64() and rt_sigtimedwait_time64()
>> >in the very near future.
>>
>> Right, I remember you pointing this out in a prior mail.
>> Thanks for working on this for such a long time now, Arnd!
>> Can we agree to move on with the procfd syscall given the current
>constraints?
>> I just don't want to see the syscall being
>> blocked by a generic problem whose
>> ultimate solution is to get rid of weird
>> architectural constraints.
>
>Creating and using a copy_siginfo_from_user64() function would work
>for everyone, no?

Meaning, no compat syscalls, introduce 
new struct siginfo64_t and the copy 
function you named above?