Re: [RFC][PATCH 00/29] Disintegrate and kill asm/system.h

On Wednesday 07 March 2012, David Howells wrote:

Arnd Bergmann [off-list ref] wrote:

quoted

One part you were missing seems to be include/asm-generic/system.h, which is
used on openrisc and contains a lot of the things you move to other
places. It would be helpful to split that up as well.

Hmmm...  okay.  How that is used from an arch that doesn't have an
asm/system.h?

We're migration towards using generic-y in arch/*/include/arm/Kbuild now.
When you create header files that have reasonable defaults that can be
shared across multiple architectures, I think you should do that for the
new header files as well.

quoted

quoted

    (4) asm/atomic.h

        Move xchg() and cmpxchg() here as they're full word atomic ops and
        frequently used by atomic_xchg() and atomic_cmpxchg().

Well, the thing with xchg and cmpxchg is that they operate on arbirary-sized
integers, not atomic_t, unlike everything else in atomic.h.

Some architectures already have an asm/cmpxchg.h, which seems more appropriate
here.

So I saw.  It might be worth making an asm/xchg.h and asm/cmpxchg.h for each
arch - or maybe just put both in asm/xchg.h or asm/cmpxchg.h.  Where do I
include it from though?  One nice thing about sticking them in asm/atomic.h is
that usually gets all instances, and they're frequently used from there.  How
about I have asm/atomic.h #include asm/{,cmp}xchg.h?

Yes, that makes sense and is probably required anyway for the obvious implementation
of atomic_cmpxchg().

	Arnd