Re: lockdep trace from posix timers

[Steven Rostedt]

On Mon, 2012-08-20 at 13:50 +0200, Peter Zijlstra wrote:
> On Mon, 2012-08-20 at 13:44 +0200, Peter Zijlstra wrote:
> >  int
> > +task_work_add(struct task_struct *task, struct callback_head *work, bool notify)
> >  {
> > +       struct callback_head **head = &task->task_works;
> > +       struct callback_head *entry, *old_entry;
> > +
> > +       entry = &head;
> 
> My compiler just alerted me that: 
> 
> 	entry = *head; 
> 
> works a lot better..
> 
> > +       for (;;) {
> > +               if (entry == &dead)

But your compiler likes "entry == &dead"? ;-)

-- Steve

> > +                       return -ESRCH;
> > +
> > +               old_entry = entry;
> > +               work->next = entry;
> > +               entry = cmpxchg(head, old_entry, work);
> > +               if (entry == old_entry)
> > +                       break;
> > +       }
> >  
> >         /* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */
> >         if (notify)
> >                 set_notify_resume(task);
> > +
> >         return 0;
> >  } 


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