Re: [RFC PATCH v4 01/12] __wr_after_init: Core and default arch

[Igor Stoppa]

On 12/02/2019 04:39, Matthew Wilcox wrote:
> On Tue, Feb 12, 2019 at 01:27:38AM +0200, Igor Stoppa wrote:
> > +#ifndef CONFIG_PRMEM
> [...]
> > +#else
> > +
> > +#include <linux/mm.h>
>
> It's a mistake to do conditional includes like this.  That way you see
> include loops with some configs and not others.  Our headers are already
> so messy, better to just include mm.h unconditionally.

ok

Can I still do the following, in prmem.c ?

#ifdef CONFIG_ARCH_HAS_PRMEM_HEADER
+#include <asm/prmem.h>
+#else
+
+struct wr_state {
+       struct mm_struct *prev;
+};
+
+#endif


It's still a conditional include, but it's in a C file, it shouldn't 
cause any chance of loops.

The alternative is that each arch supporting prmem must have a 
(probably) empty asm/prmem.h header.

I did some reasearch about telling the compiler to include a header only 
if it exists, but it doesn't seem to be a gcc feature.

--
igor