Messages in this thread | | | Date | Tue, 19 Feb 2019 16:27:16 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v2 09/10] genirq/irqdomain: fall back to default domain when creating hierarchy domain |
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On Tue, 19 Feb 2019 16:57:23 +0100 Thomas Bogendoerfer <tbogendoerfer@suse.de> wrote:
Hi Thomas,
> When creating hierarchy domains use irq_default_domain as parent, if no > parent was given by the caller. This avoids adding helper code for > querying the underlying platform irq domain. > > Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> > --- > kernel/irq/irqdomain.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > index 8b0be4bd6565..617c482d0778 100644 > --- a/kernel/irq/irqdomain.c > +++ b/kernel/irq/irqdomain.c > @@ -1021,7 +1021,10 @@ struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent, > else > domain = irq_domain_create_tree(fwnode, ops, host_data); > if (domain) { > - domain->parent = parent; > + if (parent) > + domain->parent = parent; > + else > + domain->parent = irq_default_domain; > domain->flags |= flags; > } >
I'm really not keen on this. The whole "default domain" made sense at a distant point in time (when irqdomains were new and platform code was blissfully ignoring it), but it really looks like a sore spot in the hierarchy code, which assumes that you always know what you're building your hierarchy on top of.
It also create a small issue in the sense that you can create a root domain using irq_domain_create_hierarchy() by passing NULL as the parent. With this patch, the new domain now points to the default one, with unexpected consequences.
So let's come back to first principles: How comes you can't obtain the parent domain at creation time? Because I'd rather give you a way to retrieve it instead if this.
M. (who wish he had an IP27!) -- Without deviation from the norm, progress is not possible.
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