From: Ben Collins
Date: Wed Oct 15 2003 - 21:27:29 EST
On Wed, Oct 15, 2003 at 10:53:59AM -0700, Andrew Morton wrote:
> Ben Collins <bcollins@xxxxxxxxxx> 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
I might have to dig that out and try to make use of it. Thanks for the
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