[PATCH] pcmcia: irq probe can be done without risking an IRQ storm

[PATCH] pcmcia: irq probe can be done without risking an IRQ storm

[Alan Cox]

Nowdays you can ask for an IRQ to be allocated but not enabled, when
PCMCIA was written this was not true and this feature is thus not used

Signed-off-by: Alan Cox <alan@redhat.com>

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c
--- linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 16:52:14.000000000 +0100
+++ linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 17:10:42.000000000 +0100
@@ -810,8 +810,11 @@
 		type = IRQF_SHARED;
 	if (req->Attributes & IRQ_TYPE_DYNAMIC_SHARING)
 		type = IRQF_SHARED;	
 #ifdef CONFIG_PCMCIA_PROBE
+	if (!(req->Attributes & IRQ_HANDLE_PRESENT))
+		type |= IRQ_NOAUTOEN;
+
 	if (s->irq.AssignedIRQ != 0) {
 		/* If the interrupt is already assigned, it must be the same */
 		irq = s->irq.AssignedIRQ;

Re: [PATCH] pcmcia: irq probe can be done without risking an IRQ storm

[Andrew Morton]

On Thu, 5 Apr 2007 14:09:36 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> Nowdays you can ask for an IRQ to be allocated but not enabled, when
> PCMCIA was written this was not true and this feature is thus not used
> 
> Signed-off-by: Alan Cox <alan@redhat.com>
> 
> diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c
> --- linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 16:52:14.000000000 +0100
> +++ linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 17:10:42.000000000 +0100
> @@ -810,8 +810,11 @@
>  		type = IRQF_SHARED;
>  	if (req->Attributes & IRQ_TYPE_DYNAMIC_SHARING)
>  		type = IRQF_SHARED;	
>  #ifdef CONFIG_PCMCIA_PROBE
> +	if (!(req->Attributes & IRQ_HANDLE_PRESENT))
> +		type |= IRQ_NOAUTOEN;
> +
>  	if (s->irq.AssignedIRQ != 0) {
>  		/* If the interrupt is already assigned, it must be the same */
>  		irq = s->irq.AssignedIRQ;

alpha:

drivers/pcmcia/pcmcia_resource.c: In function 'pcmcia_request_irq':
drivers/pcmcia/pcmcia_resource.c:816: error: 'IRQ_NOAUTOEN' undeclared (first use in this function)
drivers/pcmcia/pcmcia_resource.c:816: error: (Each undeclared identifier is reported only once
drivers/pcmcia/pcmcia_resource.c:816: error: for each function it appears in.)

Problem is, IRQ_NOAUTOEN is a generic-irq thing, so architectures which
don't use generic-irqs break.  And it's defined in linux/irq.h which
(stupidly) cannot be included in generic code.

Re: [PATCH] pcmcia: irq probe can be done without risking an IRQ storm

[Thomas Gleixner]

On Wed, 2007-04-25 at 21:18 -0700, Andrew Morton wrote:
> On Thu, 5 Apr 2007 14:09:36 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> 
> > Nowdays you can ask for an IRQ to be allocated but not enabled, when
> > PCMCIA was written this was not true and this feature is thus not used
> > 
> > Signed-off-by: Alan Cox <alan@redhat.com>
> > 
> > diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c
> > --- linux.vanilla-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 16:52:14.000000000 +0100
> > +++ linux-2.6.21-rc5-mm4/drivers/pcmcia/pcmcia_resource.c	2007-04-03 17:10:42.000000000 +0100
> > @@ -810,8 +810,11 @@
> >  		type = IRQF_SHARED;
> >  	if (req->Attributes & IRQ_TYPE_DYNAMIC_SHARING)
> >  		type = IRQF_SHARED;	
> >  #ifdef CONFIG_PCMCIA_PROBE
> > +	if (!(req->Attributes & IRQ_HANDLE_PRESENT))
> > +		type |= IRQ_NOAUTOEN;
> > +
> >  	if (s->irq.AssignedIRQ != 0) {
> >  		/* If the interrupt is already assigned, it must be the same */
> >  		irq = s->irq.AssignedIRQ;
> 
> alpha:
> 
> drivers/pcmcia/pcmcia_resource.c: In function 'pcmcia_request_irq':
> drivers/pcmcia/pcmcia_resource.c:816: error: 'IRQ_NOAUTOEN' undeclared (first use in this function)
> drivers/pcmcia/pcmcia_resource.c:816: error: (Each undeclared identifier is reported only once
> drivers/pcmcia/pcmcia_resource.c:816: error: for each function it appears in.)
> 
> Problem is, IRQ_NOAUTOEN is a generic-irq thing, so architectures which
> don't use generic-irqs break.  And it's defined in linux/irq.h which
> (stupidly) cannot be included in generic code.

Hrmpf. We need a IRQF_NOAUTOEN, which can be handed to reqeust_irq().

I cook a patch.

	tglx

Re: [PATCH] pcmcia: irq probe can be done without risking an IRQ storm

[Thomas Gleixner]

On Thu, 2007-04-26 at 19:31 +0200, Thomas Gleixner wrote:
> > >  #ifdef CONFIG_PCMCIA_PROBE
> > > +	if (!(req->Attributes & IRQ_HANDLE_PRESENT))
> > > +		type |= IRQ_NOAUTOEN;
> > > +
> > >  	if (s->irq.AssignedIRQ != 0) {
> > >  		/* If the interrupt is already assigned, it must be the same */
> > >  		irq = s->irq.AssignedIRQ;
> > 
> > alpha:
> > 
> > drivers/pcmcia/pcmcia_resource.c: In function 'pcmcia_request_irq':
> > drivers/pcmcia/pcmcia_resource.c:816: error: 'IRQ_NOAUTOEN' undeclared (first use in this function)
> > drivers/pcmcia/pcmcia_resource.c:816: error: (Each undeclared identifier is reported only once
> > drivers/pcmcia/pcmcia_resource.c:816: error: for each function it appears in.)
> > 
> > Problem is, IRQ_NOAUTOEN is a generic-irq thing, so architectures which
> > don't use generic-irqs break.  And it's defined in linux/irq.h which
> > (stupidly) cannot be included in generic code.
> 
> Hrmpf. We need a IRQF_NOAUTOEN, which can be handed to reqeust_irq().
> 
> I cook a patch.

Not that simple. For non shared interrupts it is straight forward, but
for shared ones we have to decide, whether we 

A) reject the request
B) disable the interrupt and rely on the caller, that it reenables it
C) ignore it

sorted by ugliness order :)

A) is definitely the most safe bet, but B) might work as well.

	tglx