Re: [RFC] typechecking for get_unaligned/put_unaligned

[Al Viro <viro@ftp.linux.org.uk>]

On Wed, Oct 18, 2006 at 01:42:42AM -0400, Dave Jones wrote:
> On Tue, Oct 17, 2006 at 05:37:26AM +0100, Al Viro wrote:
> 
>  > There are several #includes with very high impact; the worst happens
>  > to be module.h -> sched.h
> 
> I gave up fighting to get that fixed a year and a half ago..
> http://lkml.org/lkml/2005/1/26/11
> 
> rediffing trees with lots of include file juggling gets boring real fast.

I don't see a lot of files touched by that one...
 arch/i386/kernel/alternative.c            |    1 +
 arch/i386/kernel/cpu/mcheck/therm_throt.c |    1 +
 drivers/base/cpu.c                        |    1 +
 drivers/hwmon/abituguru.c                 |    1 +
 drivers/leds/ledtrig-ide-disk.c           |    1 +
 drivers/leds/ledtrig-timer.c              |    1 +
 drivers/scsi/scsi_transport_sas.c         |    1 +
 drivers/w1/slaves/w1_therm.c              |    1 +
 include/asm-x86_64/elf.h                  |    1 -
 include/linux/acct.h                      |    1 +
 include/linux/module.h                    |    3 ++-
 include/linux/phy.h                       |    2 ++
 include/scsi/libiscsi.h                   |    2 ++
 kernel/latency.c                          |    1 +
 kernel/module.c                           |    2 +-
is hardly a lot.

That's the point, actually - apparently we have several high-impact includes
that are easy to sever and that are really worth being severed.  The part
that was not aproiri obvious:
	* there are clusters of headers around certain dependency
counts.
	* such clusters tend to have leaders - header that pulls the
rest and even though other headers are apparently independently included,
all such includes end up being hidden by includes of the leader.
	* gaps between the clusters are pretty large.
	* dependency graph *on* *clusters* is worth being studied; includes
of cluster leader from cluster around slightly smaller dependency count
are prime targets for severing.

That is the new part here.  Not just "dependency graph is a mess and ought
to be cleaned up" - _that_ is neither new nor particulary useful...