Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751453AbdHFVm5 (ORCPT ); Sun, 6 Aug 2017 17:42:57 -0400 Received: from mail-oi0-f65.google.com ([209.85.218.65]:35238 "EHLO mail-oi0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351AbdHFVmz (ORCPT ); Sun, 6 Aug 2017 17:42:55 -0400 MIME-Version: 1.0 In-Reply-To: <20170806213330.GA31101@lakka.kapsi.fi> References: <20170806164428.2273-1-mikko.rapeli@iki.fi> <20170806164428.2273-19-mikko.rapeli@iki.fi> <20170806205654.GF28459@lakka.kapsi.fi> <20170806213330.GA31101@lakka.kapsi.fi> From: Willem de Bruijn Date: Sun, 6 Aug 2017 17:42:13 -0400 Message-ID: Subject: Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in user space To: Mikko Rapeli Cc: LKML , Linux API , Willem de Bruijn , Soheil Hassas Yeganeh , Network Development Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2291 Lines: 54 On Sun, Aug 6, 2017 at 5:33 PM, Mikko Rapeli wrote: > On Sun, Aug 06, 2017 at 05:24:20PM -0400, Willem de Bruijn wrote: >> >> > +#ifdef __KERNEL__ >> >> > +#include >> >> > +#else >> >> > +#include >> >> > +#endif /* __KERNEL__ */ >> >> >> >> This will break applications that include manually. >> >> I previously sent a patch to use libc-compat to make compilation succeed >> >> when both are included in the case where is included after >> >> . >> >> >> >> https://lkml.org/lkml/2016/9/12/872 >> >> >> >> The inverse will require changes to the libc header to avoid redefining >> >> symbols already defined by >> >> >> >> The second patch in that 2-patch set included >> >> unconditionally after the fix. This broke builds that also included >> >> in the wrong order. I did not resubmit the first patch as a >> >> stand-alone, as it is not sufficient to avoid breakage. >> > >> > I wasn't aware of your change, but I was about to send this to fix the >> > case when glibc is included before : >> > >> > https://github.com/mcfrisk/linux/commit/f3952a27b8a21c6478d26e6246055383483f6a66 >> >> There are a few differences between the two. Including does not >> unconditionally define all the symbols. Some are conditional on additional >> state, such as __timespec_defined. > > Yep, your patch seems better for libc-compat.h. Could you send it again? Okay. Or feel free to include it in the patchset if that helps resolve dependencies. >> > I don't like leaving a few dozen non-compiling header files into uapi. >> >> I agree, but I do not see a simple solution. >> >> Unless libc has the analogous change, including either or >> in userspace can unfortunately cause breakage. >> >> The added include if __KERNEL__ is defined should be safe, though. > > Yes, for the kernel side, but your libc-compat change would nice for > userspace, where something will break for sure, but providing source > API compatibility is sometimes impossible. > > To summarize, this change from me, and your libc-compat.c for time.h, or? I'm still afraid that this patch as is will break builds that include first.