Re: [PATCH 2.6.27-rc5 incremental re-resubmit] Fix itimer/many thread hang.

[Frank Mayhar <fmayhar@google.com>]

On Tue, 2008-09-30 at 08:33 +0200, Ingo Molnar wrote:
> * Frank Mayhar <fmayhar@google.com> wrote:
> 
> >  /*
> >   * Return any ns on the sched_clock that have not yet been banked in
> >   * @p in case that task is currently running.
> > - *
> > - * Called with task_rq_lock() held on @rq.
> >   */
> > -static unsigned long long task_delta_exec(struct task_struct *p, struct rq *rq)
> > +unsigned long long task_delta_exec(struct task_struct *p)
> >  {
> > +	struct rq *rq;
> > +	unsigned long flags;
> > +	u64 ns = 0;
> > +
> >  	if (task_current(rq, p)) {
> >  		u64 delta_exec;
> 
> hmmm ... where do we get 'rq' from?
> 
> in v3 you did this:
> 
> -       rq = task_rq_lock(p, &flags);
> 
> which removed the deadlock but left us with a random uninitialized rq 
> variable ...

You know, I just knew I had a brain around here _somewhere_.

Weirdly, this didn't fall over on any of my testing.  The gods know what
it was actually doing, though.

I'm picking up tip/master right now and will test your fix for this
shortly.
-- 
Frank Mayhar <fmayhar@google.com>
Google, Inc.