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Date: Wed, 4 Feb 2009 16:25:52 -0800 (PST) From: Davide Libenzi <davidel@...ilserver.org> To: Andrew Morton <akpm@...ux-foundation.org> cc: Michael Kerrisk <mtk.manpages@...il.com>, mtk.manpages@...glemail.com, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, linux-api@...r.kernel.org Subject: Re: [patch/rfc] eventfd semaphore-like behavior On Wed, 4 Feb 2009, Andrew Morton wrote: > On Thu, 5 Feb 2009 12:59:07 +1300 > Michael Kerrisk <mtk.manpages@...glemail.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. 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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