On Sun, Aug 06, 2017 at 05:42:13PM -0400, Willem de Bruijn wrote: > On Sun, Aug 6, 2017 at 5:33 PM, Mikko Rapeli <mikko.rapeli@xxxxxx> wrote: > > On Sun, Aug 06, 2017 at 05:24:20PM -0400, Willem de Bruijn wrote: > >> >> > +#ifdef __KERNEL__ > >> >> > +#include <linux/time.h> > >> >> > +#else > >> >> > +#include <time.h> > >> >> > +#endif /* __KERNEL__ */ > >> >> > >> >> This will break applications that include <linux/time.h> manually. > >> >> I previously sent a patch to use libc-compat to make compilation succeed > >> >> when both are included in the case where <linux/time.h> is included after > >> >> <time.h>. > >> >> > >> >> https://lkml.org/lkml/2016/9/12/872 > >> >> > >> >> The inverse will require changes to the libc header to avoid redefining > >> >> symbols already defined by <linux/time.h> > >> >> > >> >> The second patch in that 2-patch set included <linux/time.h> > >> >> unconditionally after the fix. This broke builds that also included > >> >> <time.h> 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 <time.h> is included before <linux/time.h>: > >> > > >> > https://github.com/mcfrisk/linux/commit/f3952a27b8a21c6478d26e6246055383483f6a66 > >> > >> There are a few differences between the two. Including <time.h> 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. If you don't have the time, I will send tomorrow a new version of this patch which fixes the commit topic and before that your libc-compat.h change so both could be applied together. Feel free to be faster :) > >> > 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 <time.h> or > >> <linux/time.h> 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 > <linux/time.h> first. I agree, but I also want uapi headers to cleanly compile. I know this might break stuff on userspace side which rely on these broken header file dependencies, but if the fix to just re-order include statements I'm fine with it, also when the complaints hit my inbox. If I had the CPU time, memory and disk space, I'd do a full yocto distro build to see how badly userspace could break but I don't at home. -Mikko -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
