Shared interrupts do not go well with disabling auto enable: 1) The sharing interrupt might request it while it's still disabled and then wait for interrupts forever.
2) The interrupt might have been requested by the driver sharing the line before IRQ_NOAUTOEN has been set. So the driver which expects that disabled state after calling request_irq() will not get what it wants. Even worse, when it calls enable_irq() later, it will trigger the unbalanced enable_irq() warning. Reported-by: Brian Norris <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> --- kernel/irq/chip.c | 7 +++++++ kernel/irq/manage.c | 12 ++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-) --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -942,6 +942,13 @@ void irq_modify_status(unsigned int irq, if (!desc) return; + + /* + * Warn when a driver sets the no autoenable flag on an already + * active interrupt. + */ + WARN_ON_ONCE(!desc->depth && (set & IRQF_NOAUTOEN)); + irq_settings_clr_and_set(desc, clr, set); irqd_clear(&desc->irq_data, IRQD_NO_BALANCING | IRQD_PER_CPU | --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1328,11 +1328,19 @@ static int if (new->flags & IRQF_ONESHOT) desc->istate |= IRQS_ONESHOT; - if (irq_settings_can_autoenable(desc)) + if (irq_settings_can_autoenable(desc)) { irq_startup(desc, true); - else + } else { + /* + * Shared interrupts do not go well with disabling + * auto enable. The sharing interrupt might request + * it while it's still disabled and then wait for + * interrupts forever. + */ + WARN_ON_ONCE(new->flags & IRQF_SHARED); /* Undo nested disables: */ desc->depth = 1; + } /* Exclude IRQ from balancing if requested */ if (new->flags & IRQF_NOBALANCING) {
