Many drivers don't want interrupts enabled automatically due to request_irq(). So they are handling this issue by either way of the below two: (1) irq_set_status_flags(irq, IRQ_NOAUTOEN); request_irq(dev, irq...); (2) request_irq(dev, irq...); disable_irq(irq);
The code in the second way is silly and unsafe. In the small time gap between request_irq() and disable_irq(), interrupts can still come. The code in the first way is safe though we might be able to do it in the generic irq code.
With this patch, drivers can request_irq with IRQF_NO_AUTOEN flag. They will need neither irq_set_status_flags() nor disable_irq().
In the meantime, drivers using the below pattern for NMI irq_set_status_flags(irq, IRQ_NOAUTOEN); request_nmi(dev, irq...);
can also move to request_nmi() with IRQF_NO_AUTOEN flag.
Cc: Dmitry Torokhov dmitry.torokhov@gmail.com Signed-off-by: Barry Song song.bao.hua@hisilicon.com --- -v5: * add the same check for IRQF_NO_AUTOEN in request_nmi()
include/linux/interrupt.h | 4 ++++ kernel/irq/manage.c | 11 +++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 967e25767153..76f1161a441a 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -61,6 +61,9 @@ * interrupt handler after suspending interrupts. For system * wakeup devices users need to implement wakeup detection in * their interrupt handlers. + * IRQF_NO_AUTOEN - Don't enable IRQ or NMI automatically when users request it. + * Users will enable it explicitly by enable_irq() or enable_nmi() + * later. */ #define IRQF_SHARED 0x00000080 #define IRQF_PROBE_SHARED 0x00000100 @@ -74,6 +77,7 @@ #define IRQF_NO_THREAD 0x00010000 #define IRQF_EARLY_RESUME 0x00020000 #define IRQF_COND_SUSPEND 0x00040000 +#define IRQF_NO_AUTOEN 0x00080000
#define IRQF_TIMER (__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index dec3f73e8db9..97c231a5644c 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1693,7 +1693,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) irqd_set(&desc->irq_data, IRQD_NO_BALANCING); }
- if (irq_settings_can_autoenable(desc)) { + if (!(new->flags & IRQF_NO_AUTOEN) && + irq_settings_can_autoenable(desc)) { irq_startup(desc, IRQ_RESEND, IRQ_START_COND); } else { /* @@ -2086,10 +2087,15 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler, * which interrupt is which (messes up the interrupt freeing * logic etc). * + * Also 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. + * * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and * it cannot be set along with IRQF_NO_SUSPEND. */ if (((irqflags & IRQF_SHARED) && !dev_id) || + ((irqflags & IRQF_SHARED) && (irqflags & IRQF_NO_AUTOEN)) || (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) || ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND))) return -EINVAL; @@ -2245,7 +2251,8 @@ int request_nmi(unsigned int irq, irq_handler_t handler,
desc = irq_to_desc(irq);
- if (!desc || irq_settings_can_autoenable(desc) || + if (!desc || (irq_settings_can_autoenable(desc) && + !(irqflags & IRQF_NO_AUTOEN)) || !irq_settings_can_request(desc) || WARN_ON(irq_settings_is_per_cpu_devid(desc)) || !irq_supports_nmi(desc))