Re: [patch 02/12] futex: Move futex exit handling into futex code

[Thomas Gleixner]

On Thu, 7 Nov 2019, Peter Zijlstra wrote:
> On Wed, Nov 06, 2019 at 10:55:36PM +0100, Thomas Gleixner wrote:
> 
> > -#ifdef CONFIG_FUTEX
> > -	if (unlikely(tsk->robust_list)) {
> > -		exit_robust_list(tsk);
> > -		tsk->robust_list = NULL;
> > -	}
> > -#ifdef CONFIG_COMPAT
> > -	if (unlikely(tsk->compat_robust_list)) {
> > -		compat_exit_robust_list(tsk);
> > -		tsk->compat_robust_list = NULL;
> > -	}
> > -#endif
> > -	if (unlikely(!list_empty(&tsk->pi_state_list)))
> > -		exit_pi_state_list(tsk);
> > -#endif
> 
> > +void futex_mm_release(struct task_struct *tsk)
> > +{
> > +	if (unlikely(tsk->robust_list)) {
> > +		exit_robust_list(tsk);
> > +		tsk->robust_list = NULL;
> > +	}
> > +
> > +	if (IS_ENABLED(CONFIG_COMPAT)) {
> > +		if (unlikely(tsk->compat_robust_list)) {
> > +			compat_exit_robust_list(tsk);
> > +			tsk->compat_robust_list = NULL;
> > +		}
> > +	}
> 
> I suppose it is this substitution that causes the compile error mingo
> found. The problem with IS_ENABLED() is that the whole block still needs
> to compile (before it can be thrown out), and in this case
> tsk->compat_robust_list doesn't exist.

Yeah. Tried to be overly smart :)