[RFC PATCH v2 08/12] arm64: cmpxchg: Include build_bug.h instead of bug.h for BUILD_BUG

On Tue, Feb 27, 2018 at 05:33:23PM +0000, Will Deacon wrote:

On Mon, Feb 26, 2018 at 03:48:49PM +0000, Mark Rutland wrote:

quoted

On Mon, Feb 26, 2018 at 03:04:56PM +0000, Will Deacon wrote:

quoted

Having asm/cmpxchg.h pull in linux/bug.h is problematic because this
ends up pulling in the atomic bitops which themselves may be built on
top of atomic.h and cmpxchg.h.

Instead, just include build_bug.h for the definition of BUILD_BUG.

We also use VM_BUG_ON(), defined in <linux/mmdebug.h>, which includes
<linux/bug.h>.

... so I think we still have some fragility here, albeit no worse than before.

We also miss includes for:

* <linux/percpu-defs.h> (raw_cpu_ptr)
* <linux/preempt.h> (preempt_disable, preempt_enable)

Hmm, we can't include this one because it pulls in linux/bitops.h. I've
moved the percpu cmpxchg stuff into asm/percpu.h, but that too is missing
the linux/preempt.h #include, so I've added that as well.

Generally, I think if we want to clean up our #includes then that's better
done as a separate series rather than as a piecemeal effort, which will
likely fail to identify many of the underlying problems.

Sure thing; the above shouldn't hold up this series.

Mark.