| Message ID | 20210105021411.34020-1-song.bao.hua@hisilicon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] genirq: add IRQF_NO_AUTOEN for request_irq | expand |
On Tue, Jan 05, 2021 at 03:14:11PM +1300, Barry Song wrote: > 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(). > Hundreds of drivers with this problem will be handled afterwards. > > Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> > Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Can you also convert some in-kernel drivers to this new api so that we can see how this works? thanks, greg k-h
> -----Original Message----- > From: Greg KH [mailto:gregkh@linuxfoundation.org] > Sent: Friday, January 8, 2021 7:58 AM > To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com> > Cc: tglx@linutronix.de; maz@kernel.org; linux-input@vger.kernel.org; > linux-kernel@vger.kernel.org; linuxarm@openeuler.org; Dmitry Torokhov > <dmitry.torokhov@gmail.com> > Subject: Re: [PATCH v2] genirq: add IRQF_NO_AUTOEN for request_irq > > On Tue, Jan 05, 2021 at 03:14:11PM +1300, Barry Song wrote: > > 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(). > > Hundreds of drivers with this problem will be handled afterwards. > > > > Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> > > Can you also convert some in-kernel drivers to this new api so that we > can see how this works? Sure. As the discussion got started from input, so I'll take some input drivers as examples before moving to other folders. > > thanks, > > greg k-h Thanks Barry
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..2b28314e2572 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); + if (irq_settings_can_autoenable(desc)) { irq_startup(desc, IRQ_RESEND, IRQ_START_COND); } else { @@ -2086,10 +2089,15 @@ 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; diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h index 403378b9947b..a28958a9c548 100644 --- a/kernel/irq/settings.h +++ b/kernel/irq/settings.h @@ -145,6 +145,16 @@ static inline bool irq_settings_can_move_pcntxt(struct irq_desc *desc) return desc->status_use_accessors & _IRQ_MOVE_PCNTXT; } +static inline void irq_settings_clr_noautoen(struct irq_desc *desc) +{ + desc->status_use_accessors &= ~_IRQ_NOAUTOEN; +} + +static inline void irq_settings_set_noautoen(struct irq_desc *desc) +{ + desc->status_use_accessors |= _IRQ_NOAUTOEN; +} + static inline bool irq_settings_can_autoenable(struct irq_desc *desc) { return !(desc->status_use_accessors & _IRQ_NOAUTOEN);
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(). Hundreds of drivers with this problem will be handled afterwards. Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> --- -v2: refuse the cases IRQF_NO_AUTOEN + IRQF_DISABLED are both set with respect to Dmitry's feedback in v1 include/linux/interrupt.h | 3 +++ kernel/irq/manage.c | 8 ++++++++ kernel/irq/settings.h | 10 ++++++++++ 3 files changed, 21 insertions(+)