Date: Wed, 28 Apr 2004 15:41:08 -0400 From: John Baldwin <jhb@FreeBSD.org> To: Julian Elischer <julian@elischer.org> Cc: Alex Lyashkov <shadow@psoft.net> Subject: Re: code cleanup Message-ID: <200404281541.08851.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0404281120480.73191-100000@InterJet.elischer.org> References: <Pine.BSF.4.21.0404281120480.73191-100000@InterJet.elischer.org>
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On Wednesday 28 April 2004 02:26 pm, Julian Elischer wrote:
> On Wed, 28 Apr 2004, John Baldwin wrote:
> > On Wednesday 28 April 2004 02:26 am, Alex Lyashkov wrote:
> > > Hi All
> > >
> > > how i see many points at kernel work with allproc list direct, but
> > > proc.h introduce macros FOREACH_PROC_IN_SYSTEM.
> > > This patch clean this places.
> >
> > I'd actually rather see the FOREACH_PROC macro removed, I don't think
> > hiding the fact that it's a TAILQ is all that useful.
>
> it makes it possible (well, easier) to do:
>
> FOREACH_PROC_IN_SYSTEM(p) {
> FOREACH_KSEGROUP_IN_PROC(p, kg) {
> FOREACH_THREAD_IN_GROUP(kg.td) {
> something(td, kg);
> }
> }
> }
>
> Which is a lot easier to read and understand
> than the expanded version. You don't kave to remember the linkage
> pointer's names and you can add debugging to it
> and check that the correct loks are held etc.
> (the latter being a major reason I did it).
Note that the allproc_lock protects the allproc list. W/o the FOREACH_PROC
macro, I can grep for 'allproc' in the source tree to find all users to
verify locking, etc. With the extra macro, I now have to do multiple greps.
When you multiple the effect with several wrapper macros, it now becomes much
more work to work on locking the lists of structures since you have to do
multiple greps to find the places to look at. I think remembering the
linkages for lists is actually quite important to avoid using the same
linkage for multiple lists incorrectly.
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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