quoted

quoted

+#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.

but you also ran into problems where <linux/time.h> is included before
<time.h> which need fixes in libc header side.

So how to proceed with these?

The libc-compat change is a good fix that can be submitted on its own.

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.