Re: [PATCH 20/62] sparc: irq: Remove IRQF_DISABLED

Thomas Gleixner
2011-09-07T17:33:57Z

On Wed, 7 Sep 2011, Thomas Gleixner wrote:

> On Wed, 7 Sep 2011, David Miller wrote:
>
> > From: Yong Zhang <yong.zhang0@gmail.com>
> > Date: Wed, 7 Sep 2011 16:10:17 +0800
> >
> > > This flag is a NOOP and can be removed now.
> > >
> > > Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
> >
> > How are things working now, if that is the case?
> >
> > Specifically in the ldc_bind() case, we're passing iRQF_DISABLED here
> > so that the IRQ is not turned on when we request the IRQ, we later do
> > enable_irq() on these after we've take the spinlock in this function.
> >
> > The IRQ cannot be allowed to be delivered between the request_irq()
> > call and the enable_irq() calls.
> >
> > This sequence is necessary to deal with some lock ordering issues.
>
> IRQF_DISABLED was telling the core code that the interrupt must run
> with interrupts disabled. As we enforced running all handlers with
> interrupts disabled the flag is meaningless. It was defined as 0
> anyway.
>
> What you need to prevent that request_irq() enables the interrupt
> unconditionally, is to set IRQ_NOAUTOEN on the interrupt, which can't
> be handed in to request_irq(). You want to call
>
> irq_set_status_flags(irq, IRQ_NOAUTOEN);
>
> for that irq. That tells request_irq() to leave the interrupt disabled
> and you have to explicitely enable it. That has not changed since we
> generalized the irq core code back in 2006.

If that's an issue, then we can create an IRQF_NOAUTOEN flag, which
can be handed into request_irq().

Thanks,

tglx