Re: 2.6.0-test7-mm1

[Ben Collins <bcollins@debian.org>]

On Wed, Oct 15, 2003 at 10:53:59AM -0700, Andrew Morton wrote:
> Ben Collins <bcollins@debian.org> wrote:
> >
> > > highlevel_add_host() does read_lock() and then proceeds to do things like
> >  > starting kernel threads under that lock.  The locking is pretty broken
> >  > in there :(
> > 
> >  No, highlevel_add_host() itself doesn't start any threads. But it does
> >  pass around data that needs to be locked from changes, and one of the
> >  handlers happens to start a thread, and other things allocate memory
> >  (such as this case).
> > 
> >  It's ugly, and I've been trying to clean it up. This case can be fixed
> >  quickly with a simple check in hpsb_create_hostinfo() to pass GFP_ATOMIC
> >  to kmalloc.
> 
> nodemgr_add_host() looks like the hard one.  Maybe make hl_drivers_lock a
> sleeping lock?

Problem is, things like bus resets happen in interrupt, and while I can
push off some things to occur in the nodemgr thread, a lot of other
stuff has to happen in the interrupt, and they require the same lock.

It's all a matter of just tossing out my todo list for a good week and
redoing all of this logic from the ground up. I have high hopes this
will happen in the next few weeks, but I'm not signing any contracts to
hold me to it :)

> >  My problem right now, is I don't use any architectures that support
> >  preempt, so I don't see a lot of these problems, like I catch with
> >  CONFIG_SMP.
> 
> Anton had a ppc64 patch which implemented the preempt_count beancounting
> without actually implementing premption.  So might_sleep() does the right
> thing.

I might have to dig that out and try to make use of it. Thanks for the
pointer.

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