Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature

[Byungchul Park]

On Tue, Feb 28, 2017 at 02:05:13PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 18, 2017 at 10:17:32PM +0900, Byungchul Park wrote:
> > +#define MAX_XHLOCKS_NR 64UL
> 
> > +#ifdef CONFIG_LOCKDEP_CROSSRELEASE
> > +	if (tsk->xhlocks) {
> > +		void *tmp = tsk->xhlocks;
> > +		/* Disable crossrelease for current */
> > +		tsk->xhlocks = NULL;
> > +		vfree(tmp);
> > +	}
> > +#endif
> 
> > +#ifdef CONFIG_LOCKDEP_CROSSRELEASE
> > +	p->xhlock_idx = 0;
> > +	p->xhlock_idx_soft = 0;
> > +	p->xhlock_idx_hard = 0;
> > +	p->xhlock_idx_nmi = 0;
> > +	p->xhlocks = vzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR);
> 
> I don't think we need vmalloc for this now.

Really? When is a better time to do it?

I think the time creating a task is the best time to initialize it. No?

> 
> > +	p->work_id = 0;
> > +#endif
> 
> > +#ifdef CONFIG_LOCKDEP_CROSSRELEASE
> > +	if (p->xhlocks) {
> > +		void *tmp = p->xhlocks;
> > +		/* Diable crossrelease for current */
> > +		p->xhlocks = NULL;
> > +		vfree(tmp);
> > +	}
> > +#endif
> 
> Second instance of the same code, which would suggest using a function
> for this. Also, with a function you can loose the #ifdeffery.

Yes. It looks much better.

Thank you very much.