Re: [PATCH] Fix deadlock in __create_workqueue

[Rusty Russell <rusty@rustcorp.com.au>]

On Mon, 2004-05-03 at 22:23, Srivatsa Vaddagiri wrote:
> On Fri, Apr 30, 2004 at 07:27:12PM -0700, Andrew Morton wrote:
> > Can we not simply do:
> > 
> > 
> > diff -puN kernel/workqueue.c~a kernel/workqueue.c
> > --- 25/kernel/workqueue.c~a	2004-04-30 19:26:32.003303600 -0700
> > +++ 25-akpm/kernel/workqueue.c	2004-04-30 19:26:44.492404968 -0700
> > @@ -334,6 +334,7 @@ struct workqueue_struct *__create_workqu
> >  				destroy = 1;
> >  		}
> >  	}
> > +	unlock_cpu_hotplug();
> >  
> >  	/*
> >  	 * Was there any error during startup? If yes then clean up:
> > @@ -342,7 +343,6 @@ struct workqueue_struct *__create_workqu
> >  		destroy_workqueue(wq);
> >  		wq = NULL;
> >  	}
> > -	unlock_cpu_hotplug();
> >  	return wq;
> >  }
> 
> I didn't do this because I introduced a break at the first instance
> when create_workqueue_thread failed. Breaking out of the loop
> like that appeared to be more efficient rather than going back and
> trying to create threads for rest of the online cpus, because most
> likely thread creation will fail for other cpus also and anyway
> the workqueue will be destroyed down the line.

The logic was not the way I would have done it, but it *is* neater.  I
prefer the akpm fix I think.

Rusty.
-- 
Anyone who quotes me in their signature is an idiot -- Rusty Russell