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

From: Paul E. McKenney
Date: Thu Feb 02 2012 - 13:01:12 EST


On Wed, Feb 01, 2012 at 09:53:11PM -0800, 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. :)

Error? What error?

Good eyes, fixed!

> A quick check turns up the same bug in rcutorture_onoff_init.

Which is of course where I started when creating rcu_torture_stall_init().

> This suggests a possible Coccinelle check, for uses of PTR_ERR(foo) after
> foo = (any constant other than ERR_PTR(foo)).

And I took the resulting patch, thank you!

Thanx, Paul

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