Re: [PATCH v6 18/23] xen/riscv: implement IRQ routing for device passthrough

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 7/29/26 4:15 PM, Jan Beulich wrote:
> On 29.07.2026 13:59, Oleksii Kurochko wrote:
> > On 7/23/26 3:30 PM, Jan Beulich wrote:
> > > On 20.07.2026 17:59, Oleksii Kurochko wrote:
> > > > +/* Route an IRQ to a specific guest */
> > > > +int route_irq_to_guest(struct domain *d, unsigned int virq,
> > > > +                       unsigned int irq, const char *devname)
> > > > +{
> > > > +    struct irqaction *action;
> > > > +    struct irq_guest *info;
> > > > +    struct irq_desc *desc;
> > > > +    unsigned long flags;
> > > > +    int retval = 0;
> > > > +
> > > > +    if ( d->is_dying )
> > > > +        return -EINVAL;
> > > > +
> > > > +    desc = irq_to_desc(irq);
> > > > +
> > > > +    /*
> > > > +     * release_irq() frees this action via xvfree(), relying on action
> > > > +     * being the first member of struct irq_guest so that &info->action
> > > > +     * coincides with info itself. Guard the layout so a future field
> > > > +     * reorder can't silently turn that into a free() of a mid-allocation
> > > > +     * pointer.
> > > > +     */
> > > > +    BUILD_BUG_ON(offsetof(struct irq_guest, action) != 0);
> > > Can't release_irq() simply use container_of()? One way or another it feels
> > > like you're painting yourself into a particular corner ...
> > If it isn't the best option then it is needed to follow they way we had
> > before:
> I don't understand why you think you need to go back.
Because, based on your reply—specifically, "One way or another it feels 
like you're painting yourself into a particular corner..." — it seems 
that even if I replaced BUILD_BUG_ON() with container_of() in 
release_irq(), you would still consider it a bad solution. Did I 
misunderstand your point?
~ Oleksii