Messages in this thread | | | Date | Wed, 4 Feb 2009 16:18:16 -0800 | From | Andrew Morton <> | Subject | Re: [patch/rfc] eventfd semaphore-like behavior |
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On Thu, 5 Feb 2009 12:59:07 +1300 Michael Kerrisk <mtk.manpages@googlemail.com> 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.
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