Re: [PATCH v2] epoll: add nsec timeout support

[Willem de Bruijn]

On Mon, Nov 16, 2020 at 11:19 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Mon, Nov 16, 2020 at 11:10:01AM -0500, Willem de Bruijn wrote:
> > diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
> > index 8a3432d0f0dc..f6ef9c9f8ac2 100644
> > --- a/include/uapi/linux/eventpoll.h
> > +++ b/include/uapi/linux/eventpoll.h
> > @@ -21,6 +21,7 @@
> >
> >  /* Flags for epoll_create1.  */
> >  #define EPOLL_CLOEXEC O_CLOEXEC
> > +#define EPOLL_NSTIMEO 0x1
> >
> >  /* Valid opcodes to issue to sys_epoll_ctl() */
> >  #define EPOLL_CTL_ADD 1
>
> Not a problem with your patch, but this concerns me.  O_CLOEXEC is
> defined differently for each architecture, so we need to stay out of
> several different bits when we define new flags for EPOLL_*.  Maybe
> this:
>
> /*
>  * Flags for epoll_create1.  O_CLOEXEC may be different bits, depending
>  * on the CPU architecture.  Reserve the known ones.
>  */
> #define EPOLL_CLOEXEC           O_CLOEXEC
> #define EPOLL_RESERVED_FLAGS    0x00680000
> #define EPOLL_NSTIMEO           0x00000001

Thanks. Good point, I'll add that in v3.