From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch/rfc] eventfd semaphore-like behavior Date: Wed, 4 Feb 2009 16:18:16 -0800 Message-ID: <20090204161816.b93a4588.akpm@linux-foundation.org> References: <20090204150507.665b5b7c.akpm@linux-foundation.org> <20090204152434.c8f65d52.akpm@linux-foundation.org> <20090204155514.6abbdc8f.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Cc: mtk.manpages-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org, davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Thu, 5 Feb 2009 12:59:07 +1300 Michael Kerrisk 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. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html