[PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[Marc Zyngier]

With the landing of stacked irq domains in 3.19, we have ended up in a
situation where we have a stack of IRQ controllers, each with their
set of flags, but the core code is only able to look at the top-most,
which is not very helpful. This small series is trying to fix this.

The first patch converts all access to desc->irq_data.chip->flags to
using an accessor, without changing anything else. The second patch
adds some logic to combine these flags as we allocate the interrupts,
ultimately storing the resulting set as part of the irq_desc
structure.

We end-up with a configuration where the flags can either be located
in the irq_chip structure (non stacked case), or in the irq_desc
(stacked case). While this isn't really ideal, this gives at least the
right level of information to the rest of the IRQ framework.

Based on 3.19-rc3, and available at:
git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/stacked-irqchip-flags

Marc Zyngier (2):
  genirq: Abstract access to irq_chip flags
  genirq: Allow irq_desc to carry the union of stacked irq_chip flags

 include/linux/irq.h     |  4 ++++
 include/linux/irqdesc.h | 12 ++++++++++++
 kernel/irq/chip.c       | 10 +++++-----
 kernel/irq/irqdesc.c    |  3 +++
 kernel/irq/irqdomain.c  | 20 +++++++++++++++++++-
 kernel/irq/manage.c     |  6 +++---
 kernel/irq/pm.c         |  2 +-
 7 files changed, 47 insertions(+), 10 deletions(-)

-- 
2.1.4

[PATCH 1/2] genirq: Abstract access to irq_chip flags

[Marc Zyngier]

In order to safely migrate to a cumulative set of flags, start by
abstracting the way we look at these flags. There is otherwise no
change in semantics here.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 include/linux/irqdesc.h |  5 +++++
 kernel/irq/chip.c       | 10 +++++-----
 kernel/irq/manage.c     |  6 +++---
 kernel/irq/pm.c         |  2 +-
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index faf433a..32d9fff 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -107,6 +107,11 @@ static inline void *irq_desc_get_chip_data(struct irq_desc *desc)
 	return desc->irq_data.chip_data;
 }
 
+static inline unsigned long irq_desc_get_chip_flags(struct irq_desc *desc)
+{
+	return desc->irq_data.chip->flags;
+}
+
 static inline void *irq_desc_get_handler_data(struct irq_desc *desc)
 {
 	return desc->irq_data.handler_data;
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6f1c7a5..d8ffb36 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -287,7 +287,7 @@ void unmask_threaded_irq(struct irq_desc *desc)
 {
 	struct irq_chip *chip = desc->irq_data.chip;
 
-	if (chip->flags & IRQCHIP_EOI_THREADED)
+	if (irq_desc_get_chip_flags(desc) & IRQCHIP_EOI_THREADED)
 		chip->irq_eoi(&desc->irq_data);
 
 	if (chip->irq_unmask) {
@@ -489,7 +489,7 @@ static void cond_unmask_eoi_irq(struct irq_desc *desc, struct irq_chip *chip)
 	    irqd_irq_masked(&desc->irq_data) && !desc->threads_oneshot) {
 		chip->irq_eoi(&desc->irq_data);
 		unmask_irq(desc);
-	} else if (!(chip->flags & IRQCHIP_EOI_THREADED)) {
+	} else if (!(irq_desc_get_chip_flags(desc) & IRQCHIP_EOI_THREADED)) {
 		chip->irq_eoi(&desc->irq_data);
 	}
 }
@@ -538,7 +538,7 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
 	raw_spin_unlock(&desc->lock);
 	return;
 out:
-	if (!(chip->flags & IRQCHIP_EOI_IF_HANDLED))
+	if (!(irq_desc_get_chip_flags(desc) & IRQCHIP_EOI_IF_HANDLED))
 		chip->irq_eoi(&desc->irq_data);
 	raw_spin_unlock(&desc->lock);
 }
@@ -836,7 +836,7 @@ void irq_cpu_online(void)
 
 		chip = irq_data_get_irq_chip(&desc->irq_data);
 		if (chip && chip->irq_cpu_online &&
-		    (!(chip->flags & IRQCHIP_ONOFFLINE_ENABLED) ||
+		    (!(irq_desc_get_chip_flags(desc) & IRQCHIP_ONOFFLINE_ENABLED) ||
 		     !irqd_irq_disabled(&desc->irq_data)))
 			chip->irq_cpu_online(&desc->irq_data);
 
@@ -866,7 +866,7 @@ void irq_cpu_offline(void)
 
 		chip = irq_data_get_irq_chip(&desc->irq_data);
 		if (chip && chip->irq_cpu_offline &&
-		    (!(chip->flags & IRQCHIP_ONOFFLINE_ENABLED) ||
+		    (!(irq_desc_get_chip_flags(desc) & IRQCHIP_ONOFFLINE_ENABLED) ||
 		     !irqd_irq_disabled(&desc->irq_data)))
 			chip->irq_cpu_offline(&desc->irq_data);
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8069237..b2a43e0 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -491,7 +491,7 @@ static int set_irq_wake_real(unsigned int irq, unsigned int on)
 	struct irq_desc *desc = irq_to_desc(irq);
 	int ret = -ENXIO;
 
-	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
+	if (irq_desc_get_chip_flags(desc) &  IRQCHIP_SKIP_SET_WAKE)
 		return 0;
 
 	if (desc->irq_data.chip->irq_set_wake)
@@ -589,7 +589,7 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 
 	flags &= IRQ_TYPE_SENSE_MASK;
 
-	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
+	if (irq_desc_get_chip_flags(desc) & IRQCHIP_SET_TYPE_MASKED) {
 		if (!irqd_irq_masked(&desc->irq_data))
 			mask_irq(desc);
 		if (!irqd_irq_disabled(&desc->irq_data))
@@ -1043,7 +1043,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 	 * chip flags, so we can avoid the unmask dance at the end of
 	 * the threaded handler for those.
 	 */
-	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
+	if (irq_desc_get_chip_flags(desc) & IRQCHIP_ONESHOT_SAFE)
 		new->flags &= ~IRQF_ONESHOT;
 
 	/*
diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index 3ca5325..8ed029d 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -88,7 +88,7 @@ static bool suspend_device_irq(struct irq_desc *desc, int irq)
 	 * chip level. The chip implementation indicates that with
 	 * IRQCHIP_MASK_ON_SUSPEND.
 	 */
-	if (irq_desc_get_chip(desc)->flags & IRQCHIP_MASK_ON_SUSPEND)
+	if (irq_desc_get_chip_flags(desc) & IRQCHIP_MASK_ON_SUSPEND)
 		mask_irq(desc);
 	return true;
 }
-- 
2.1.4

[PATCH 2/2] genirq: Allow irq_desc to carry the union of stacked irq_chip flags

[Marc Zyngier]

The current infrastructure for stacked domains doesn't propagate
irq_chip flags, and as we only look at the top-level irq_chip,
we may miss a number of critical flags.

This patch accumulates the flags into a new set, stored at the
irq_desc level, with an additional flag to indicate that this is
a stack of irqchip. The accessor is updated to return the right one.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 include/linux/irq.h     |  4 ++++
 include/linux/irqdesc.h |  7 +++++++
 kernel/irq/irqdesc.c    |  3 +++
 kernel/irq/irqdomain.c  | 20 +++++++++++++++++++-
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index d09ec7a..cb956f6 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -377,6 +377,7 @@ struct irq_chip {
  * IRQCHIP_SKIP_SET_WAKE:	Skip chip.irq_set_wake(), for this irq chip
  * IRQCHIP_ONESHOT_SAFE:	One shot does not require mask/unmask
  * IRQCHIP_EOI_THREADED:	Chip requires eoi() on unmask in threaded mode
+ * IRQCHIP_STACKED_CHIPS:	Pseudo flag for stacked irq chips
  */
 enum {
 	IRQCHIP_SET_TYPE_MASKED		= (1 <<  0),
@@ -386,6 +387,9 @@ enum {
 	IRQCHIP_SKIP_SET_WAKE		= (1 <<  4),
 	IRQCHIP_ONESHOT_SAFE		= (1 <<  5),
 	IRQCHIP_EOI_THREADED		= (1 <<  6),
+
+	/* The following is only valid as part of irq_desc.chip_flags */
+	IRQCHIP_STACKED_CHIPS		= (1 << 31),
 };
 
 /* This include will go away once we isolated irq_desc usage to core code */
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 32d9fff..f35f192 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -50,6 +50,9 @@ struct irq_desc {
 	struct irq_data		irq_data;
 	unsigned int __percpu	*kstat_irqs;
 	irq_flow_handler_t	handle_irq;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	unsigned long		chip_flags;	/* Union of all the irqchips */
+#endif
 #ifdef CONFIG_IRQ_PREFLOW_FASTEOI
 	irq_preflow_handler_t	preflow_handler;
 #endif
@@ -109,6 +112,10 @@ static inline void *irq_desc_get_chip_data(struct irq_desc *desc)
 
 static inline unsigned long irq_desc_get_chip_flags(struct irq_desc *desc)
 {
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	if (desc->chip_flags & IRQCHIP_STACKED_CHIPS)
+		return desc->chip_flags;
+#endif
 	return desc->irq_data.chip->flags;
 }
 
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 99793b9..b916ea4 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -84,6 +84,9 @@ static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
 	irq_settings_clr_and_set(desc, ~0, _IRQ_DEFAULT_INIT_FLAGS);
 	irqd_set(&desc->irq_data, IRQD_IRQ_DISABLED);
 	desc->handle_irq = handle_bad_irq;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	desc->chip_flags = 0;
+#endif
 	desc->depth = 1;
 	desc->irq_count = 0;
 	desc->irqs_unhandled = 0;
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 7fac311..3d0e366 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1013,6 +1013,17 @@ static void irq_domain_free_irqs_recursive(struct irq_domain *domain,
 	}
 }
 
+static void irq_desc_update_chip_flags(struct irq_domain *domain,
+				       unsigned int virq)
+{
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	struct irq_desc *desc = irq_to_desc(virq);
+	struct irq_data *data = irq_domain_get_irq_data(domain, virq);
+
+	desc->chip_flags |= data->chip->flags | IRQCHIP_STACKED_CHIPS;
+#endif
+}
+
 static int irq_domain_alloc_irqs_recursive(struct irq_domain *domain,
 					   unsigned int irq_base,
 					   unsigned int nr_irqs, void *arg)
@@ -1025,8 +1036,15 @@ static int irq_domain_alloc_irqs_recursive(struct irq_domain *domain,
 	if (recursive)
 		ret = irq_domain_alloc_irqs_recursive(parent, irq_base,
 						      nr_irqs, arg);
-	if (ret >= 0)
+	if (ret >= 0) {
 		ret = domain->ops->alloc(domain, irq_base, nr_irqs, arg);
+		if (ret >= 0) {
+			int i;
+
+			for (i = 0; i < nr_irqs; i++)
+				irq_desc_update_chip_flags(domain, irq_base + i);
+		}
+	}
 	if (ret < 0 && recursive)
 		irq_domain_free_irqs_recursive(parent, irq_base, nr_irqs);
 
-- 
2.1.4

Re: [PATCH 1/2] genirq: Abstract access to irq_chip flags

[Jiang Liu]

On 2015/1/9 1:32, Marc Zyngier wrote:
> In order to safely migrate to a cumulative set of flags, start by
> abstracting the way we look at these flags. There is otherwise no
> change in semantics here.
<snit>
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index 8069237..b2a43e0 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -491,7 +491,7 @@ static int set_irq_wake_real(unsigned int irq, unsigned int on)
>  	struct irq_desc *desc = irq_to_desc(irq);
>  	int ret = -ENXIO;
>  
> -	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
> +	if (irq_desc_get_chip_flags(desc) &  IRQCHIP_SKIP_SET_WAKE)
>  		return 0;
>  
>  	if (desc->irq_data.chip->irq_set_wake)
> @@ -589,7 +589,7 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
>  
>  	flags &= IRQ_TYPE_SENSE_MASK;
>  
> -	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
> +	if (irq_desc_get_chip_flags(desc) & IRQCHIP_SET_TYPE_MASKED) {
>  		if (!irqd_irq_masked(&desc->irq_data))
>  			mask_irq(desc);
>  		if (!irqd_irq_disabled(&desc->irq_data))
> @@ -1043,7 +1043,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
>  	 * chip flags, so we can avoid the unmask dance at the end of
>  	 * the threaded handler for those.
>  	 */
> -	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
> +	if (irq_desc_get_chip_flags(desc) & IRQCHIP_ONESHOT_SAFE)
>  		new->flags &= ~IRQF_ONESHOT;
>  
>  	/*
Hi Mark,
	Seems you missed on instance of IRQCHIP_ONESHOT_SAFE in
__setup_irq() as below.
Thanks!
Gerry
-----------------------------------------------------------------
        } else if (new->handler == irq_default_primary_handler &&
                   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
------------------------------------------------------------------

> diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
> index 3ca5325..8ed029d 100644
> --- a/kernel/irq/pm.c
> +++ b/kernel/irq/pm.c
> @@ -88,7 +88,7 @@ static bool suspend_device_irq(struct irq_desc *desc, int irq)
>  	 * chip level. The chip implementation indicates that with
>  	 * IRQCHIP_MASK_ON_SUSPEND.
>  	 */
> -	if (irq_desc_get_chip(desc)->flags & IRQCHIP_MASK_ON_SUSPEND)
> +	if (irq_desc_get_chip_flags(desc) & IRQCHIP_MASK_ON_SUSPEND)
>  		mask_irq(desc);
>  	return true;
>  }
> 

Re: [PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[Jiang Liu]

On 2015/1/9 1:32, Marc Zyngier wrote:
> With the landing of stacked irq domains in 3.19, we have ended up in a
> situation where we have a stack of IRQ controllers, each with their
> set of flags, but the core code is only able to look at the top-most,
> which is not very helpful. This small series is trying to fix this.
> 
> The first patch converts all access to desc->irq_data.chip->flags to
> using an accessor, without changing anything else. The second patch
> adds some logic to combine these flags as we allocate the interrupts,
> ultimately storing the resulting set as part of the irq_desc
> structure.
> 
> We end-up with a configuration where the flags can either be located
> in the irq_chip structure (non stacked case), or in the irq_desc
> (stacked case). While this isn't really ideal, this gives at least the
> right level of information to the rest of the IRQ framework.
Hi Mark,
	By this way, we need to aggregate irq_chip flags for every
irq. How about changing irq_desc_get_chip_flags(struct irq_desc *desc)
to irq_desc_check_chip_flags(struct irq_desc *desc, unsigned int flags)
which dynamically walks the stacked irqchips?
Thanks!
Gerry

> 
> Based on 3.19-rc3, and available at:
> git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/stacked-irqchip-flags
> 
> Marc Zyngier (2):
>   genirq: Abstract access to irq_chip flags
>   genirq: Allow irq_desc to carry the union of stacked irq_chip flags
> 
>  include/linux/irq.h     |  4 ++++
>  include/linux/irqdesc.h | 12 ++++++++++++
>  kernel/irq/chip.c       | 10 +++++-----
>  kernel/irq/irqdesc.c    |  3 +++
>  kernel/irq/irqdomain.c  | 20 +++++++++++++++++++-
>  kernel/irq/manage.c     |  6 +++---
>  kernel/irq/pm.c         |  2 +-
>  7 files changed, 47 insertions(+), 10 deletions(-)
> 

Re: [PATCH 1/2] genirq: Abstract access to irq_chip flags

[Marc Zyngier]

On 09/01/15 03:00, Jiang Liu wrote:
> On 2015/1/9 1:32, Marc Zyngier wrote:
>> In order to safely migrate to a cumulative set of flags, start by
>> abstracting the way we look at these flags. There is otherwise no
>> change in semantics here.
> <snit>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index 8069237..b2a43e0 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -491,7 +491,7 @@ static int set_irq_wake_real(unsigned int irq, unsigned int on)
>>  	struct irq_desc *desc = irq_to_desc(irq);
>>  	int ret = -ENXIO;
>>  
>> -	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
>> +	if (irq_desc_get_chip_flags(desc) &  IRQCHIP_SKIP_SET_WAKE)
>>  		return 0;
>>  
>>  	if (desc->irq_data.chip->irq_set_wake)
>> @@ -589,7 +589,7 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
>>  
>>  	flags &= IRQ_TYPE_SENSE_MASK;
>>  
>> -	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
>> +	if (irq_desc_get_chip_flags(desc) & IRQCHIP_SET_TYPE_MASKED) {
>>  		if (!irqd_irq_masked(&desc->irq_data))
>>  			mask_irq(desc);
>>  		if (!irqd_irq_disabled(&desc->irq_data))
>> @@ -1043,7 +1043,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
>>  	 * chip flags, so we can avoid the unmask dance at the end of
>>  	 * the threaded handler for those.
>>  	 */
>> -	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
>> +	if (irq_desc_get_chip_flags(desc) & IRQCHIP_ONESHOT_SAFE)
>>  		new->flags &= ~IRQF_ONESHOT;
>>  
>>  	/*
> Hi Mark,
> 	Seems you missed on instance of IRQCHIP_ONESHOT_SAFE in
> __setup_irq() as below.
> Thanks!
> Gerry
> -----------------------------------------------------------------
>         } else if (new->handler == irq_default_primary_handler &&
>                    !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
> ------------------------------------------------------------------

Ah, nice catch.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[Marc Zyngier]

Hi Jiang,

On 09/01/15 03:07, Jiang Liu wrote:
> On 2015/1/9 1:32, Marc Zyngier wrote:
>> With the landing of stacked irq domains in 3.19, we have ended up in a
>> situation where we have a stack of IRQ controllers, each with their
>> set of flags, but the core code is only able to look at the top-most,
>> which is not very helpful. This small series is trying to fix this.
>>
>> The first patch converts all access to desc->irq_data.chip->flags to
>> using an accessor, without changing anything else. The second patch
>> adds some logic to combine these flags as we allocate the interrupts,
>> ultimately storing the resulting set as part of the irq_desc
>> structure.
>>
>> We end-up with a configuration where the flags can either be located
>> in the irq_chip structure (non stacked case), or in the irq_desc
>> (stacked case). While this isn't really ideal, this gives at least the
>> right level of information to the rest of the IRQ framework.
> Hi Mark,
> 	By this way, we need to aggregate irq_chip flags for every
> irq. How about changing irq_desc_get_chip_flags(struct irq_desc *desc)
> to irq_desc_check_chip_flags(struct irq_desc *desc, unsigned int flags)
> which dynamically walks the stacked irqchips?

That was the other option, but I felt that going through the list of
irqchips was not a very nice idea performance wise. This is used is some
moderately hot paths (cond_unmask_eoi_irq, for example), and I wondered
if we wanted to pay this price at runtime...

Thoughts?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[Thomas Gleixner]

On Fri, 9 Jan 2015, Marc Zyngier wrote:
> Hi Jiang,
> 
> On 09/01/15 03:07, Jiang Liu wrote:
> > On 2015/1/9 1:32, Marc Zyngier wrote:
> >> With the landing of stacked irq domains in 3.19, we have ended up in a
> >> situation where we have a stack of IRQ controllers, each with their
> >> set of flags, but the core code is only able to look at the top-most,
> >> which is not very helpful. This small series is trying to fix this.
> >>
> >> The first patch converts all access to desc->irq_data.chip->flags to
> >> using an accessor, without changing anything else. The second patch
> >> adds some logic to combine these flags as we allocate the interrupts,
> >> ultimately storing the resulting set as part of the irq_desc
> >> structure.
> >>
> >> We end-up with a configuration where the flags can either be located
> >> in the irq_chip structure (non stacked case), or in the irq_desc
> >> (stacked case). While this isn't really ideal, this gives at least the
> >> right level of information to the rest of the IRQ framework.
> > Hi Mark,
> > 	By this way, we need to aggregate irq_chip flags for every
> > irq. How about changing irq_desc_get_chip_flags(struct irq_desc *desc)
> > to irq_desc_check_chip_flags(struct irq_desc *desc, unsigned int flags)
> > which dynamically walks the stacked irqchips?
> 
> That was the other option, but I felt that going through the list of
> irqchips was not a very nice idea performance wise. This is used is some
> moderately hot paths (cond_unmask_eoi_irq, for example), and I wondered
> if we wanted to pay this price at runtime...

We rather do it at setup time.

Re: [PATCH 0/2] genirq: Make irqchip flags work with stacked irq domains

[Marc Zyngier]

On 13/01/15 10:41, Thomas Gleixner wrote:
> On Fri, 9 Jan 2015, Marc Zyngier wrote:
>> Hi Jiang,
>>
>> On 09/01/15 03:07, Jiang Liu wrote:
>>> On 2015/1/9 1:32, Marc Zyngier wrote:
>>>> With the landing of stacked irq domains in 3.19, we have ended up in a
>>>> situation where we have a stack of IRQ controllers, each with their
>>>> set of flags, but the core code is only able to look at the top-most,
>>>> which is not very helpful. This small series is trying to fix this.
>>>>
>>>> The first patch converts all access to desc->irq_data.chip->flags to
>>>> using an accessor, without changing anything else. The second patch
>>>> adds some logic to combine these flags as we allocate the interrupts,
>>>> ultimately storing the resulting set as part of the irq_desc
>>>> structure.
>>>>
>>>> We end-up with a configuration where the flags can either be located
>>>> in the irq_chip structure (non stacked case), or in the irq_desc
>>>> (stacked case). While this isn't really ideal, this gives at least the
>>>> right level of information to the rest of the IRQ framework.
>>> Hi Mark,
>>> 	By this way, we need to aggregate irq_chip flags for every
>>> irq. How about changing irq_desc_get_chip_flags(struct irq_desc *desc)
>>> to irq_desc_check_chip_flags(struct irq_desc *desc, unsigned int flags)
>>> which dynamically walks the stacked irqchips?
>>
>> That was the other option, but I felt that going through the list of
>> irqchips was not a very nice idea performance wise. This is used is some
>> moderately hot paths (cond_unmask_eoi_irq, for example), and I wondered
>> if we wanted to pay this price at runtime...
> 
> We rather do it at setup time.

That was my thought as well. I'll respin the series with Jiang's fix.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...