On Wed, 4 Feb 2009, Andrew Morton wrote:
> On Thu, 5 Feb 2009 12:59:07 +1300
> Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx> wrote:
>
> > >> > > > What should be userspace's fallback strategy if that support is not
> > >> > > > present?
> > >> > >
> > >> > > #ifdef EFD_SEMAPHORE, maybe?
> > >> >
> > >> > That's compile-time. People who ship binaries will probably want
> > >> > to find a runtime thing for back-compatibility.
> > >>
> > >> I dunno. How do they actually do when we add new flags, like the O_ ones?
> > >>
> > >
> > > Dunno. Probably try the syscall and see if it returned -EINVAL. Does
> > > that work in this case?
> >
> > As youll have seen by now, Ulrich and I noted that it works.
>
> I think you means "should work" ;)
>
> We're talking about this, yes?
>
> SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
> {
> int fd;
> struct eventfd_ctx *ctx;
>
> /* Check the EFD_* constants for consistency. */
> BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
> BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK);
>
> if (flags & ~(EFD_CLOEXEC | EFD_NONBLOCK))
> return -EINVAL;
>
> That looks like it should work to me.
I lost you guys. On old kernels you'd get -EINVAL when using the new flag.
Wasn't it clear? Or is there some side-band traffic in this conversation
that I missed? :)
- Davide
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