Re: [PATCH] rcu: Use IRQ_WORK_INIT_HARD for srcu's irq_work

On Thu, 20 Aug 2026 15:55:00 +0200
Sebastian Andrzej Siewior <[email protected]> wrote:

> > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> > > index 7c2f7cc131f7a..b703233d4a63f 100644
> > > --- a/kernel/rcu/srcutree.c
> > > +++ b/kernel/rcu/srcutree.c
> > > @@ -218,7 +218,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
> > >  	mutex_init(&ssp->srcu_sup->srcu_barrier_mutex);
> > >  	atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0);
> > >  	INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu);
> > > -	init_irq_work(&ssp->srcu_sup->irq_work, srcu_irq_work);
> > > +	ssp->srcu_sup->irq_work = IRQ_WORK_INIT_HARD(srcu_irq_work);  
> > 
> > It may need a comment to not lose that.  

I agree a comment would be useful here.

> 
> We could also make irq_work.o earlier in the Makefile, right at the top
> so it comes before tracing. This was one of the first ideas and makes
> the issue also go away. But given that it is just a wake we avoid waking
> the irq_work/ thread just to schedule a timer/ wake workqueue.

That doesn't sound as robust as this solution. Updating Makefile order
is a fragile solution.

Anyway for this patch,

Reviewed-by: Steven Rostedt <[email protected].

-- Steve