[PATCH] No need to call irq_domain_legacy_revmap() for twice

[PATCH] No need to call irq_domain_legacy_revmap() for twice

[Mike Qiu]

Function irq_create_mapping() calls irq_find_mapping(). The later
function has checked if the indicated IRQ domain has hw IRQ mapped to
virtual IRQ through legacy mode or not and return the value of the
legacy irq number by call irq_domain_legacy_revmap(). We needn't
to call irq_domain_legacy_revmap() to do same check in
irq_create_mapping() again.

The patch removes the duplicate call.

Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
---
 kernel/irq/irqdomain.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 49a7772..286d672 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
 		return virq;
 	}
 
-	/* Get a virtual interrupt number */
+	/*
+	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
+	 * create the IRQ mapping for non-existing one, so just return 0.
+	 */
 	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
-		return irq_domain_legacy_revmap(domain, hwirq);
+		return 0;
 
 	/* Allocate a virtual interrupt number */
 	hint = hwirq % nr_irqs;
-- 
1.7.7.6

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Mike]

Any comments?
Thanks
在 2012-09-24一的 17:37 +0800，Mike Qiu写道：
> Function irq_create_mapping() calls irq_find_mapping(). The later
> function has checked if the indicated IRQ domain has hw IRQ mapped to
> virtual IRQ through legacy mode or not and return the value of the
> legacy irq number by call irq_domain_legacy_revmap(). We needn't
> to call irq_domain_legacy_revmap() to do same check in
> irq_create_mapping() again.
> 
> The patch removes the duplicate call.
> 
> Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> ---
>  kernel/irq/irqdomain.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index 49a7772..286d672 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
>  		return virq;
>  	}
> 
> -	/* Get a virtual interrupt number */
> +	/*
> +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> +	 * create the IRQ mapping for non-existing one, so just return 0.
> +	 */
>  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> -		return irq_domain_legacy_revmap(domain, hwirq);
> +		return 0;
> 
>  	/* Allocate a virtual interrupt number */
>  	hint = hwirq % nr_irqs;

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Grant Likely]

On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> Function irq_create_mapping() calls irq_find_mapping(). The later
> function has checked if the indicated IRQ domain has hw IRQ mapped to
> virtual IRQ through legacy mode or not and return the value of the
> legacy irq number by call irq_domain_legacy_revmap(). We needn't
> to call irq_domain_legacy_revmap() to do same check in
> irq_create_mapping() again.
> 
> The patch removes the duplicate call.
> 
> Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> ---
>  kernel/irq/irqdomain.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index 49a7772..286d672 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
>  		return virq;
>  	}
>  
> -	/* Get a virtual interrupt number */
> +	/*
> +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> +	 * create the IRQ mapping for non-existing one, so just return 0.
> +	 */
>  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> -		return irq_domain_legacy_revmap(domain, hwirq);
> +		return 0;

But it does need to return the virq assigned to the hwirq. That is why
it has to call the revmap function.

g.

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Mike]

在 2012-11-26一的 20:17 +0000，Grant Likely写道：
> On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> > Function irq_create_mapping() calls irq_find_mapping(). The later
> > function has checked if the indicated IRQ domain has hw IRQ mapped to
> > virtual IRQ through legacy mode or not and return the value of the
> > legacy irq number by call irq_domain_legacy_revmap(). We needn't
> > to call irq_domain_legacy_revmap() to do same check in
> > irq_create_mapping() again.
> > 
> > The patch removes the duplicate call.
> > 
> > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > ---
> >  kernel/irq/irqdomain.c |    7 +++++--
> >  1 files changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > index 49a7772..286d672 100644
> > --- a/kernel/irq/irqdomain.c
> > +++ b/kernel/irq/irqdomain.c
> > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
> >  		return virq;
> >  	}
> >  
> > -	/* Get a virtual interrupt number */
> > +	/*
> > +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> > +	 * create the IRQ mapping for non-existing one, so just return 0.
> > +	 */
> >  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> > -		return irq_domain_legacy_revmap(domain, hwirq);
> > +		return 0;
> 
> But it does need to return the virq assigned to the hwirq. That is why
> it has to call the revmap function.
> 
Yes, thanks

this judgment has been done in
 /*Check if mapping already exists*/
virq = irq_find_mapping(domain, hwirq);

if the virq equals none zero, the func irq_create_mapping will 
return the virq value directly(already exists).

otherwise, that means virq equals zero, this has two meanings, one is
haven't find the already exist mapping, the other one is in
irq_find_mapping()
	case IRQ_DOMAIN_MAP_LEGACY:
		return irq_domain_legacy_revmap(domain, hwirq); 
this may return zero.

So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero
is OK. because if it is none zero, it will be return after check if
mapping already exists, and never come here. also we never try to assign
the virq for the legacy map.

I don't know if you have understand my explanation.

Thanks 
Mike



> g.
> 

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Grant Likely]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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On Tue, 27 Nov 2012 09:41:46 +0800, Mike <qiudayu@linux.vnet.ibm.com> wrote:
> 在 2012-11-26一的 20:17 +0000，Grant Likely写道：
> > On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> > > Function irq_create_mapping() calls irq_find_mapping(). The later
> > > function has checked if the indicated IRQ domain has hw IRQ mapped to
> > > virtual IRQ through legacy mode or not and return the value of the
> > > legacy irq number by call irq_domain_legacy_revmap(). We needn't
> > > to call irq_domain_legacy_revmap() to do same check in
> > > irq_create_mapping() again.
> > > 
> > > The patch removes the duplicate call.
> > > 
> > > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > > ---
> > >  kernel/irq/irqdomain.c |    7 +++++--
> > >  1 files changed, 5 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > > index 49a7772..286d672 100644
> > > --- a/kernel/irq/irqdomain.c
> > > +++ b/kernel/irq/irqdomain.c
> > > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
> > >  		return virq;
> > >  	}
> > >  
> > > -	/* Get a virtual interrupt number */
> > > +	/*
> > > +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> > > +	 * create the IRQ mapping for non-existing one, so just return 0.
> > > +	 */
> > >  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> > > -		return irq_domain_legacy_revmap(domain, hwirq);
> > > +		return 0;
> > 
> > But it does need to return the virq assigned to the hwirq. That is why
> > it has to call the revmap function.
> > 
> Yes, thanks
> 
> this judgment has been done in
>  /*Check if mapping already exists*/
> virq = irq_find_mapping(domain, hwirq);
> 
> if the virq equals none zero, the func irq_create_mapping will 
> return the virq value directly(already exists).
> 
> otherwise, that means virq equals zero, this has two meanings, one is
> haven't find the already exist mapping, the other one is in
> irq_find_mapping()
> 	case IRQ_DOMAIN_MAP_LEGACY:
> 		return irq_domain_legacy_revmap(domain, hwirq); 
> this may return zero.
> 
> So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero
> is OK. because if it is none zero, it will be return after check if
> mapping already exists, and never come here. also we never try to assign
> the virq for the legacy map.
> 
> I don't know if you have understand my explanation.

Yes, your explanation makes sense and you are correct. I'm not going to
apply this for v3.8 (I've left it too late before the merge window), but
I'll look again after the merge window closes.

g.

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Mike]

在 2012-12-11二的 08:30 +0000，Grant Likely写道：
> On Tue, 27 Nov 2012 09:41:46 +0800, Mike <qiudayu@linux.vnet.ibm.com> wrote:
> > 在 2012-11-26一的 20:17 +0000，Grant Likely写道：
> > > On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> > > > Function irq_create_mapping() calls irq_find_mapping(). The later
> > > > function has checked if the indicated IRQ domain has hw IRQ mapped to
> > > > virtual IRQ through legacy mode or not and return the value of the
> > > > legacy irq number by call irq_domain_legacy_revmap(). We needn't
> > > > to call irq_domain_legacy_revmap() to do same check in
> > > > irq_create_mapping() again.
> > > > 
> > > > The patch removes the duplicate call.
> > > > 
> > > > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > > > ---
> > > >  kernel/irq/irqdomain.c |    7 +++++--
> > > >  1 files changed, 5 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > > > index 49a7772..286d672 100644
> > > > --- a/kernel/irq/irqdomain.c
> > > > +++ b/kernel/irq/irqdomain.c
> > > > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
> > > >  		return virq;
> > > >  	}
> > > >  
> > > > -	/* Get a virtual interrupt number */
> > > > +	/*
> > > > +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> > > > +	 * create the IRQ mapping for non-existing one, so just return 0.
> > > > +	 */
> > > >  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> > > > -		return irq_domain_legacy_revmap(domain, hwirq);
> > > > +		return 0;
> > > 
> > > But it does need to return the virq assigned to the hwirq. That is why
> > > it has to call the revmap function.
> > > 
> > Yes, thanks
> > 
> > this judgment has been done in
> >  /*Check if mapping already exists*/
> > virq = irq_find_mapping(domain, hwirq);
> > 
> > if the virq equals none zero, the func irq_create_mapping will 
> > return the virq value directly(already exists).
> > 
> > otherwise, that means virq equals zero, this has two meanings, one is
> > haven't find the already exist mapping, the other one is in
> > irq_find_mapping()
> > 	case IRQ_DOMAIN_MAP_LEGACY:
> > 		return irq_domain_legacy_revmap(domain, hwirq); 
> > this may return zero.
> > 
> > So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero
> > is OK. because if it is none zero, it will be return after check if
> > mapping already exists, and never come here. also we never try to assign
> > the virq for the legacy map.
> > 
> > I don't know if you have understand my explanation.
> 
> Yes, your explanation makes sense and you are correct. I'm not going to
> apply this for v3.8 (I've left it too late before the merge window), but
> I'll look again after the merge window closes.
> 
> g.
> 
OK, fair enough.
Thanks 

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Mike]

在 2012-12-11二的 08:30 +0000，Grant Likely写道：
> On Tue, 27 Nov 2012 09:41:46 +0800, Mike <qiudayu@linux.vnet.ibm.com> wrote:
> > 在 2012-11-26一的 20:17 +0000，Grant Likely写道：
> > > On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> > > > Function irq_create_mapping() calls irq_find_mapping(). The later
> > > > function has checked if the indicated IRQ domain has hw IRQ mapped to
> > > > virtual IRQ through legacy mode or not and return the value of the
> > > > legacy irq number by call irq_domain_legacy_revmap(). We needn't
> > > > to call irq_domain_legacy_revmap() to do same check in
> > > > irq_create_mapping() again.
> > > > 
> > > > The patch removes the duplicate call.
> > > > 
> > > > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > > > ---
> > > >  kernel/irq/irqdomain.c |    7 +++++--
> > > >  1 files changed, 5 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > > > index 49a7772..286d672 100644
> > > > --- a/kernel/irq/irqdomain.c
> > > > +++ b/kernel/irq/irqdomain.c
> > > > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
> > > >  		return virq;
> > > >  	}
> > > >  
> > > > -	/* Get a virtual interrupt number */
> > > > +	/*
> > > > +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> > > > +	 * create the IRQ mapping for non-existing one, so just return 0.
> > > > +	 */
> > > >  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> > > > -		return irq_domain_legacy_revmap(domain, hwirq);
> > > > +		return 0;
> > > 
> > > But it does need to return the virq assigned to the hwirq. That is why
> > > it has to call the revmap function.
> > > 
> > Yes, thanks
> > 
> > this judgment has been done in
> >  /*Check if mapping already exists*/
> > virq = irq_find_mapping(domain, hwirq);
> > 
> > if the virq equals none zero, the func irq_create_mapping will 
> > return the virq value directly(already exists).
> > 
> > otherwise, that means virq equals zero, this has two meanings, one is
> > haven't find the already exist mapping, the other one is in
> > irq_find_mapping()
> > 	case IRQ_DOMAIN_MAP_LEGACY:
> > 		return irq_domain_legacy_revmap(domain, hwirq); 
> > this may return zero.
> > 
> > So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero
> > is OK. because if it is none zero, it will be return after check if
> > mapping already exists, and never come here. also we never try to assign
> > the virq for the legacy map.
> > 
> > I don't know if you have understand my explanation.
> 
> Yes, your explanation makes sense and you are correct. I'm not going to
> apply this for v3.8 (I've left it too late before the merge window), but
> I'll look again after the merge window closes.
> 
Hi Grant 

I don't know if you forget this patch ...

I haven't see this patch in 3.9-rc7

just for a reminder

Thanks
Mike
> g.
> 

Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice

[Grant Likely]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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On Wed, 17 Apr 2013 14:48:19 +0800, Mike <qiudayu@linux.vnet.ibm.com> wrote:
> 在 2012-12-11二的 08:30 +0000，Grant Likely写道：
> > On Tue, 27 Nov 2012 09:41:46 +0800, Mike <qiudayu@linux.vnet.ibm.com> wrote:
> > > 在 2012-11-26一的 20:17 +0000，Grant Likely写道：
> > > > On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu <qiudayu@linux.vnet.ibm.com> wrote:
> > > > > Function irq_create_mapping() calls irq_find_mapping(). The later
> > > > > function has checked if the indicated IRQ domain has hw IRQ mapped to
> > > > > virtual IRQ through legacy mode or not and return the value of the
> > > > > legacy irq number by call irq_domain_legacy_revmap(). We needn't
> > > > > to call irq_domain_legacy_revmap() to do same check in
> > > > > irq_create_mapping() again.
> > > > > 
> > > > > The patch removes the duplicate call.
> > > > > 
> > > > > Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> > > > > ---
> > > > >  kernel/irq/irqdomain.c |    7 +++++--
> > > > >  1 files changed, 5 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > > > > index 49a7772..286d672 100644
> > > > > --- a/kernel/irq/irqdomain.c
> > > > > +++ b/kernel/irq/irqdomain.c
> > > > > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
> > > > >  		return virq;
> > > > >  	}
> > > > >  
> > > > > -	/* Get a virtual interrupt number */
> > > > > +	/*
> > > > > +	 * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't
> > > > > +	 * create the IRQ mapping for non-existing one, so just return 0.
> > > > > +	 */
> > > > >  	if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY)
> > > > > -		return irq_domain_legacy_revmap(domain, hwirq);
> > > > > +		return 0;
> > > > 
> > > > But it does need to return the virq assigned to the hwirq. That is why
> > > > it has to call the revmap function.
> > > > 
> > > Yes, thanks
> > > 
> > > this judgment has been done in
> > >  /*Check if mapping already exists*/
> > > virq = irq_find_mapping(domain, hwirq);
> > > 
> > > if the virq equals none zero, the func irq_create_mapping will 
> > > return the virq value directly(already exists).
> > > 
> > > otherwise, that means virq equals zero, this has two meanings, one is
> > > haven't find the already exist mapping, the other one is in
> > > irq_find_mapping()
> > > 	case IRQ_DOMAIN_MAP_LEGACY:
> > > 		return irq_domain_legacy_revmap(domain, hwirq); 
> > > this may return zero.
> > > 
> > > So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero
> > > is OK. because if it is none zero, it will be return after check if
> > > mapping already exists, and never come here. also we never try to assign
> > > the virq for the legacy map.
> > > 
> > > I don't know if you have understand my explanation.
> > 
> > Yes, your explanation makes sense and you are correct. I'm not going to
> > apply this for v3.8 (I've left it too late before the merge window), but
> > I'll look again after the merge window closes.
> > 
> Hi Grant 
> 
> I don't know if you forget this patch ...
> 
> I haven't see this patch in 3.9-rc7
> 
> just for a reminder

After taking another look at it, I'm not going to apply this patch. It
isn't actively dangerous for the revmap to get called twice, and I've
got a patch pending that removes the legacy map entirely and replaces it
with a pre-populated linear map.

g.