Re: [PATCH RFC tip/core/rcu 31/41] rcu: Add CPU-stall capability torcutorture

[Julia Lawall]

On Wed, 1 Feb 2012, Josh Triplett wrote:

> On Wed, Feb 01, 2012 at 11:41:49AM -0800, Paul E. McKenney wrote:
> > --- a/kernel/rcutorture.c
> > +++ b/kernel/rcutorture.c
> > +/* Spawn CPU-stall kthread, if stall_cpu specified. */
> > +static int __init rcu_torture_stall_init(void)
> > +{
> > +	if (stall_cpu <= 0)
> > +		return 0;
> > +	stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
> > +	if (IS_ERR(stall_task)) {
> > +		stall_task = NULL;
> > +		return PTR_ERR(stall_task);
>
> This seems...unlikely to produce the desired result. :)
>
> A quick check turns up the same bug in rcutorture_onoff_init.
>
> This suggests a possible Coccinelle check, for uses of PTR_ERR(foo) after
> foo = (any constant other than ERR_PTR(foo)).

Indeed, it seems to be a popular idiom :)  I'll send some patches later 
today.

julia
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