Re: [PATCH 3/3] kernel/irq/manage.c: disable_irq() might sleep.

[Manfred Spraul]

Hi Alexander,

On 12/20/22 07:58, Sverdlin, Alexander wrote:
> Hi Manfred!
>
> On Fri, 2022-12-16 at 16:04 +0100, Manfred Spraul wrote:
> > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> > index 5b7cf28df290..8ce75495e04f 100644
> > --- a/kernel/irq/manage.c
> > +++ b/kernel/irq/manage.c
> > @@ -723,10 +723,13 @@ EXPORT_SYMBOL(disable_irq_nosync);
> >    *     to complete before returning. If you use this function while
> >    *     holding a resource the IRQ handler may need you will
> > deadlock.
> >    *
> > - *     This function may be called - with care - from IRQ context.
> > + *     Can only be called from preemptible code as it might sleep
> > when
> > + *     an interrupt thread is associated to @irq.
> > + *
> >    */
> >   void disable_irq(unsigned int irq)
> >   {
> > +       might_sleep();
> I'm not sure about this, latest wait_event() inside synchronize_irq()
> has it already.
>
> >          if (!__disable_irq_nosync(irq))
> >                  synchronize_irq(irq);
> >   }

That is the whole point: might_sleep() should be always called. We are 
clarifying an API definition. Everyone who uses disable_irq() from 
non-sleeping context should get a warning, 100% of the time.

Not just within synchronize_irq() if there is an active threaded irq 
handler.

--

    Manfred