On Fri, 2018-03-23 at 10:54 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Hans de Goede <hdego...@redhat.com> > > > [ Upstream commit 382bd4de61827dbaaf5fb4fb7b1f4be4a86505e7 ] > > When requesting a shared irq with IRQF_TRIGGER_NONE then the irqaction > flags get filled with the trigger type from the irq_data: > > if (!(new->flags & IRQF_TRIGGER_MASK)) > new->flags |= irqd_get_trigger_type(&desc->irq_data);
The code above was added to __setup_irq() in 4.8, so I don't think this fix is needed in 3.18 or 4.4; and I suspect it might cause a regression there. Ben. > On the first setup_irq() the trigger type in irq_data is NONE when the > above code executes, then the irq is started up for the first time and > then the actual trigger type gets established, but that's too late to fix > up new->flags. > > When then a second user of the irq requests the irq with IRQF_TRIGGER_NONE > its irqaction's triggertype gets set to the actual trigger type and the > following check fails: > > if (!((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) > > Resulting in the request_irq failing with -EBUSY even though both > users requested the irq with IRQF_SHARED | IRQF_TRIGGER_NONE > > Fix this by comparing the new irqaction's trigger type to the trigger type > stored in the irq_data which correctly reflects the actual trigger type > being used for the irq. > > Suggested-by: Thomas Gleixner <t...@linutronix.de> > Signed-off-by: Hans de Goede <hdego...@redhat.com> > Acked-by: Marc Zyngier <marc.zyng...@arm.com> > Link: http://lkml.kernel.org/r/20170415100831.17073-1-hdego...@redhat.com > Signed-off-by: Thomas Gleixner <t...@linutronix.de> > Signed-off-by: Sasha Levin <alexander.le...@microsoft.com> > Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> > --- > kernel/irq/manage.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > --- a/kernel/irq/manage.c > +++ b/kernel/irq/manage.c > @@ -1189,8 +1189,10 @@ __setup_irq(unsigned int irq, struct irq > * set the trigger type must match. Also all must > * agree on ONESHOT. > */ > + unsigned int oldtype = irqd_get_trigger_type(&desc->irq_data); > + > if (!((old->flags & new->flags) & IRQF_SHARED) || > - ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) || > + (oldtype != (new->flags & IRQF_TRIGGER_MASK)) || > ((old->flags ^ new->flags) & IRQF_ONESHOT)) > goto mismatch; > -- Ben Hutchings Software Developer, Codethink Ltd.
