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

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2026-08-20 13:00:28 [-0400], Steven Rostedt wrote:
> On Thu, 20 Aug 2026 15:55:00 +0200
> Sebastian Andrzej Siewior <bigeasy@linutronix.de> 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.
Urgh.

> > 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.

This is the way how ordering in initcall works. Both are early_initcall
so if you don't tweak the makefile for ordering you would have to
introduce a level before early.

> Anyway for this patch,
> 
> Reviewed-by: Steven Rostedt <rostedt@goodmis.org.
> 
> -- Steve

Sebastian