Re: [PATCH v6 1/2 hurd] libirqhelp: Add library

[Samuel Thibault]

Damien Zammit, le mar. 11 juil. 2023 07:58:39 +0000, a ecrit:
> On 11/7/23 05:47, Samuel Thibault wrote:
> > Damien Zammit, le lun. 10 juil. 2023 09:02:10 +0000, a ecrit:
> >> +void
> >> +irqhelp_wait_init(struct irq *irq)
> >> +{
> >> +  if (!irq)
> >> +    {
> >> +      log_error("cannot wait on this irq to be ready\n");
> >> +      return;
> >> +    }
> >> +
> >> +  sem_wait(&irq->sema);
> >> +}
> > 
> > So, is this wait really necessary? Why?
> 
> Yes, without this wait, netdde.static crashes randomly on startup,
> and if it doesn't crash the first time, it can be triggered to crash
> by running ifdown then ifup.
> 
> I think the wait avoids a race.

Ok but we should really understand what race can exist, otherwise we
don't really know why the code works.

Samuel