> -----Original Message----- > From: Dmitry Torokhov [mailto:dmitry.torokhov@xxxxxxxxx] > Sent: Tuesday, January 5, 2021 12:01 PM > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx> > Cc: tglx@xxxxxxxxxxxxx; maz@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > linux-input@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linuxarm@xxxxxxxxxxxxx > Subject: Re: [PATCH] genirq: add IRQF_NO_AUTOEN for request_irq > > On Tue, Jan 05, 2021 at 11:26:12AM +1300, Barry Song wrote: > > This patch originated from the discussion with Dmitry in the below thread: > > > https://lore.kernel.org/linux-input/20210102042902.41664-1-song.bao.hua@hi > silicon.com/ > > there are many drivers which 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. > > > > I guess Dmitry also prefers genirq handles this as he said > > "What I would like to see is to allow passing something like IRQF_DISABLED > > to request_irq() so that we would not need neither irq_set_status_flags() > > nor disable_irq()" in the original email thread. > > One of the reasons I dislike irq_set_status_flags() is that we have to > call it before we actually granted our IRQ request... > > > > > If this one is accepted, hundreds of drivers with this problem will be > > handled afterwards. > > > > Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > > Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx> > > --- > > include/linux/interrupt.h | 3 +++ > > kernel/irq/manage.c | 3 +++ > > kernel/irq/settings.h | 10 ++++++++++ > > 3 files changed, 16 insertions(+) > > > > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > > index bb8ff9083e7d..0f22d277078c 100644 > > --- a/include/linux/interrupt.h > > +++ b/include/linux/interrupt.h > > @@ -61,6 +61,8 @@ > > * 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 automatically when users request it. > Users > > + * will enable it explicitly by enable_irq() later. > > */ > > #define IRQF_SHARED 0x00000080 > > #define IRQF_PROBE_SHARED 0x00000100 > > @@ -74,6 +76,7 @@ > > #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 ab8567f32501..364e8b47d9ba 100644 > > --- a/kernel/irq/manage.c > > +++ b/kernel/irq/manage.c > > @@ -1693,6 +1693,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, > struct irqaction *new) > > irqd_set(&desc->irq_data, IRQD_NO_BALANCING); > > } > > > > + if (new->flags & IRQF_NO_AUTOEN) > > + irq_settings_set_noautoen(desc); > > Can we make sure we refuse this request if the caller also specified > IRQF_SHARED? Right now, there is a warning for IRQF_SHARED + NOAUTOEN: if (irq_settings_can_autoenable(desc)) { irq_startup(desc, IRQ_RESEND, IRQ_START_COND); } 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; } Of course, this could also be clearly rejected in the sanity-check of request_threaded_irq() if we want to totally prohibit this behavior: int request_threaded_irq(unsigned int irq, irq_handler_t handler, irq_handler_t thread_fn, unsigned long irqflags, const char *devname, void *dev_id) { struct irqaction *action; struct irq_desc *desc; int retval; if (irq == IRQ_NOTCONNECTED) return -ENOTCONN; /* * Sanity-check: shared interrupts must pass in a real dev-ID, * otherwise we'll have trouble later trying to figure out * which interrupt is which (messes up the interrupt freeing * logic etc). * * 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_COND_SUSPEND)) || ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND))) return -EINVAL; > > Thanks. Thanks Barry
