Messages in this thread | | | Date | Fri, 24 Feb 2023 12:24:45 +0100 | From | Johan Hovold <> | Subject | Re: [PATCH] irqdomain: fix regression for Xen guests |
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On Thu, Feb 23, 2023 at 09:38:00AM +0100, Juergen Gross wrote: > The recent switch to per-domain locking caused a NULL dereference in > irq_domain_create_hierarchy(), as Xen code is calling > msi_create_irq_domain() with a NULL parent pointer.
This was unexpected. Apparently the Intel VMD driver also does this (see vmd_enable_domain()).
> Fix that by testing parent to be set before dereferencing it. For a > non-existing parent the irq-domain's root will stay to point to > itself.
An alternative could be to have msi_create_irq_domain() handle the no-parent case explicitly, but this looks the right fix for now (e.g. as irq_domain_create_tree() does not take a flag parameter).
> Fixes: 9dbb8e3452ab ("irqdomain: Switch to per-domain locking") > Signed-off-by: Juergen Gross <jgross@suse.com> > --- > kernel/irq/irqdomain.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > index aa5b7eeeceb8..6522dfb2e49c 100644 > --- a/kernel/irq/irqdomain.c > +++ b/kernel/irq/irqdomain.c > @@ -1172,7 +1172,8 @@ struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent, > domain = __irq_domain_create(fwnode, 0, ~0, 0, ops, host_data); > > if (domain) { > - domain->root = parent->root; > + if (parent) > + domain->root = parent->root; > domain->parent = parent; > domain->flags |= flags;
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Johan
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