4.4-stable review patch. If anyone has any objections, please let me know.
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From: Hans de Goede hdegoede@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);
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 tglx@linutronix.de Signed-off-by: Hans de Goede hdegoede@redhat.com Acked-by: Marc Zyngier marc.zyngier@arm.com Link: http://lkml.kernel.org/r/20170415100831.17073-1-hdegoede@redhat.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@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;