[PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Zeng Tao]

When CONFIG_NR_CPUS is smaller than the cpu nodes defined in the device
tree, all the cpu nodes parsing will fail.
And this is not reasonable for a legal device tree configs.
In this patch, skip such cpu nodes rather than return an error.
With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree is 130,
The following warning messages will be print during boot:
CPU node for /cpus/cpu@128 exist but the possible cpu range is :0-127
CPU node for /cpus/cpu@129 exist but the possible cpu range is :0-127
CPU node for /cpus/cpu@130 exist but the possible cpu range is :0-127

Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
---
Changelog:
v1->v2:
 -Remove redundant -ENODEV assignment in get_cpu_for_node
 -Add comment to describe the get_cpu_for_node return values
 -Add skip process for cpu threads
 -Update the commit log with more detail
---
 drivers/base/arch_topology.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 5fe44b3..01f0e21 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -248,22 +248,44 @@ core_initcall(free_raw_capacity);
 #endif
 
 #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
+/*
+ * This function returns the logic cpu number of the node.
+ * There are totally three kinds of return values:
+ * (1) logic cpu number which is > 0.
+ * (2) -ENDEV when the node is valid one which can be found in the device tree
+ * but there is no possible cpu nodes to match, when the CONFIG_NR_CPUS is
+ * smaller than cpus node numbers in device tree, this will happen. It's
+ * suggested to just ignore this case.
+ * (3) -EINVAL when other errors occur.
+ */
 static int __init get_cpu_for_node(struct device_node *node)
 {
-	struct device_node *cpu_node;
+	struct device_node *cpu_node, *t;
 	int cpu;
+	bool found = false;
 
 	cpu_node = of_parse_phandle(node, "cpu", 0);
 	if (!cpu_node)
-		return -1;
+		return -EINVAL;
+
+	for_each_of_cpu_node(t)
+		if (t == cpu_node) {
+			found = true;
+			break;
+		}
+
+	if (!found) {
+		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
+		return -EINVAL;
+	}
 
 	cpu = of_cpu_node_to_id(cpu_node);
 	if (cpu >= 0)
 		topology_parse_cpu_capacity(cpu_node, cpu);
 	else
-		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
+		pr_warn("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
+			cpu_node, cpumask_pr_args(cpu_possible_mask));
 
-	of_node_put(cpu_node);
 	return cpu;
 }
 
@@ -286,9 +308,8 @@ static int __init parse_core(struct device_node *core, int package_id,
 				cpu_topology[cpu].package_id = package_id;
 				cpu_topology[cpu].core_id = core_id;
 				cpu_topology[cpu].thread_id = i;
-			} else {
-				pr_err("%pOF: Can't get CPU for thread\n",
-				       t);
+			} else if (cpu != -ENODEV) {
+				pr_err("%pOF: Can't get CPU for thread\n", t);
 				of_node_put(t);
 				return -EINVAL;
 			}
@@ -307,7 +328,7 @@ static int __init parse_core(struct device_node *core, int package_id,
 
 		cpu_topology[cpu].package_id = package_id;
 		cpu_topology[cpu].core_id = core_id;
-	} else if (leaf) {
+	} else if (leaf && cpu != -ENODEV) {
 		pr_err("%pOF: Can't get CPU for leaf core\n", core);
 		return -EINVAL;
 	}
-- 
2.8.1

Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Sudeep Holla]

On Sat, Jan 11, 2020 at 02:53:40PM +0800, Zeng Tao wrote:
> When CONFIG_NR_CPUS is smaller than the cpu nodes defined in the device
> tree, all the cpu nodes parsing will fail.
> And this is not reasonable for a legal device tree configs.
> In this patch, skip such cpu nodes rather than return an error.
> With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree is 130,
> The following warning messages will be print during boot:
> CPU node for /cpus/cpu@128 exist but the possible cpu range is :0-127
> CPU node for /cpus/cpu@129 exist but the possible cpu range is :0-127
> CPU node for /cpus/cpu@130 exist but the possible cpu range is :0-127
> 
> Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
> ---
> Changelog:
> v1->v2:
>  -Remove redundant -ENODEV assignment in get_cpu_for_node
>  -Add comment to describe the get_cpu_for_node return values
>  -Add skip process for cpu threads
>  -Update the commit log with more detail
> ---
>  drivers/base/arch_topology.c | 37 +++++++++++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 5fe44b3..01f0e21 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -248,22 +248,44 @@ core_initcall(free_raw_capacity);
>  #endif
>  
>  #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
> +/*
> + * This function returns the logic cpu number of the node.
> + * There are totally three kinds of return values:
> + * (1) logic cpu number which is > 0.
> + * (2) -ENDEV when the node is valid one which can be found in the device tree
> + * but there is no possible cpu nodes to match, when the CONFIG_NR_CPUS is
> + * smaller than cpus node numbers in device tree, this will happen. It's
> + * suggested to just ignore this case.

s/ENDEV/ENODEV/

Also as I mentioned earlier, I prefer not to add any extra logic here
other than the above comment to make it explicit. This triggers unnecessary
warnings when someone boots with limited CPUs for valid reasons.


> + * (3) -EINVAL when other errors occur.
> + */
>  static int __init get_cpu_for_node(struct device_node *node)
>  {
> -	struct device_node *cpu_node;
> +	struct device_node *cpu_node, *t;
>  	int cpu;
> +	bool found = false;
>  
>  	cpu_node = of_parse_phandle(node, "cpu", 0);
>  	if (!cpu_node)
> -		return -1;
> +		return -EINVAL;
> +
> +	for_each_of_cpu_node(t)
> +		if (t == cpu_node) {
> +			found = true;
> +			break;
> +		}
> +
> +	if (!found) {
> +		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> +		return -EINVAL;
> +	}
>  
>  	cpu = of_cpu_node_to_id(cpu_node);
>  	if (cpu >= 0)
>  		topology_parse_cpu_capacity(cpu_node, cpu);
>  	else
> -		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> +		pr_warn("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
> +			cpu_node, cpumask_pr_args(cpu_possible_mask));
>  
> -	of_node_put(cpu_node);

Why is this dropped ?

--
Regards,
Sudeep

RE: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Zengtao (B)]

> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> Sent: Monday, January 13, 2020 6:19 PM
> To: Zengtao (B)
> Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu
> nodes
> 
> On Sat, Jan 11, 2020 at 02:53:40PM +0800, Zeng Tao wrote:
> > When CONFIG_NR_CPUS is smaller than the cpu nodes defined in the
> device
> > tree, all the cpu nodes parsing will fail.
> > And this is not reasonable for a legal device tree configs.
> > In this patch, skip such cpu nodes rather than return an error.
> > With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree is
> 130,
> > The following warning messages will be print during boot:
> > CPU node for /cpus/cpu@128 exist but the possible cpu range
> is :0-127
> > CPU node for /cpus/cpu@129 exist but the possible cpu range
> is :0-127
> > CPU node for /cpus/cpu@130 exist but the possible cpu range
> is :0-127
> >
> > Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
> > ---
> > Changelog:
> > v1->v2:
> >  -Remove redundant -ENODEV assignment in get_cpu_for_node
> >  -Add comment to describe the get_cpu_for_node return values
> >  -Add skip process for cpu threads
> >  -Update the commit log with more detail
> > ---
> >  drivers/base/arch_topology.c | 37
> +++++++++++++++++++++++++++++--------
> >  1 file changed, 29 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/base/arch_topology.c
> b/drivers/base/arch_topology.c
> > index 5fe44b3..01f0e21 100644
> > --- a/drivers/base/arch_topology.c
> > +++ b/drivers/base/arch_topology.c
> > @@ -248,22 +248,44 @@ core_initcall(free_raw_capacity);
> >  #endif
> >
> >  #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
> > +/*
> > + * This function returns the logic cpu number of the node.
> > + * There are totally three kinds of return values:
> > + * (1) logic cpu number which is > 0.
> > + * (2) -ENDEV when the node is valid one which can be found in the
> device tree
> > + * but there is no possible cpu nodes to match, when the
> CONFIG_NR_CPUS is
> > + * smaller than cpus node numbers in device tree, this will happen.
> It's
> > + * suggested to just ignore this case.
> 
> s/ENDEV/ENODEV/
Good catch, thanks.

> 
> Also as I mentioned earlier, I prefer not to add any extra logic here
> other than the above comment to make it explicit. This triggers
> unnecessary
> warnings when someone boots with limited CPUs for valid reasons.
> 

So , what 's your suggestion here? Just keep the comments but remove
 the warning message print? 
> 
> > + * (3) -EINVAL when other errors occur.
> > + */
> >  static int __init get_cpu_for_node(struct device_node *node)
> >  {
> > -	struct device_node *cpu_node;
> > +	struct device_node *cpu_node, *t;
> >  	int cpu;
> > +	bool found = false;
> >
> >  	cpu_node = of_parse_phandle(node, "cpu", 0);
> >  	if (!cpu_node)
> > -		return -1;
> > +		return -EINVAL;
> > +
> > +	for_each_of_cpu_node(t)
> > +		if (t == cpu_node) {
> > +			found = true;
> > +			break;
> > +		}
> > +
> > +	if (!found) {
> > +		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> > +		return -EINVAL;
> > +	}
> >
> >  	cpu = of_cpu_node_to_id(cpu_node);
> >  	if (cpu >= 0)
> >  		topology_parse_cpu_capacity(cpu_node, cpu);
> >  	else
> > -		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> > +		pr_warn("CPU node for %pOF exist but the possible cpu range
> is :%*pbl\n",
> > +			cpu_node, cpumask_pr_args(cpu_possible_mask));
> >
> > -	of_node_put(cpu_node);
> 
> Why is this dropped ?

It's unnecessary here since no one get the node ref.

Regards
Zengtao 

Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Sudeep Holla]

On Mon, Jan 13, 2020 at 12:06:11PM +0000, Zengtao (B) wrote:
> > -----Original Message-----
> > From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> > Sent: Monday, January 13, 2020 6:19 PM
> > To: Zengtao (B)
> > Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla;
> > linux-kernel@vger.kernel.org
> > Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu
> > nodes
> >
> > On Sat, Jan 11, 2020 at 02:53:40PM +0800, Zeng Tao wrote:
> > > When CONFIG_NR_CPUS is smaller than the cpu nodes defined in the
> > device
> > > tree, all the cpu nodes parsing will fail.
> > > And this is not reasonable for a legal device tree configs.
> > > In this patch, skip such cpu nodes rather than return an error.
> > > With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree is
> > 130,
> > > The following warning messages will be print during boot:
> > > CPU node for /cpus/cpu@128 exist but the possible cpu range
> > is :0-127
> > > CPU node for /cpus/cpu@129 exist but the possible cpu range
> > is :0-127
> > > CPU node for /cpus/cpu@130 exist but the possible cpu range
> > is :0-127
> > >
> > > Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
> > > ---
> > > Changelog:
> > > v1->v2:
> > >  -Remove redundant -ENODEV assignment in get_cpu_for_node
> > >  -Add comment to describe the get_cpu_for_node return values
> > >  -Add skip process for cpu threads
> > >  -Update the commit log with more detail
> > > ---
> > >  drivers/base/arch_topology.c | 37
> > +++++++++++++++++++++++++++++--------
> > >  1 file changed, 29 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/base/arch_topology.c
> > b/drivers/base/arch_topology.c
> > > index 5fe44b3..01f0e21 100644
> > > --- a/drivers/base/arch_topology.c
> > > +++ b/drivers/base/arch_topology.c
> > > @@ -248,22 +248,44 @@ core_initcall(free_raw_capacity);
> > >  #endif
> > >
> > >  #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
> > > +/*
> > > + * This function returns the logic cpu number of the node.
> > > + * There are totally three kinds of return values:
> > > + * (1) logic cpu number which is > 0.
> > > + * (2) -ENDEV when the node is valid one which can be found in the
> > device tree
> > > + * but there is no possible cpu nodes to match, when the
> > CONFIG_NR_CPUS is
> > > + * smaller than cpus node numbers in device tree, this will happen.
> > It's
> > > + * suggested to just ignore this case.
> >
> > s/ENDEV/ENODEV/
> Good catch, thanks.
>
> >
> > Also as I mentioned earlier, I prefer not to add any extra logic here
> > other than the above comment to make it explicit. This triggers
> > unnecessary
> > warnings when someone boots with limited CPUs for valid reasons.
> >
>
> So , what 's your suggestion here? Just keep the comments but remove
>  the warning message print?

Yes for all the "found" logic. I am fine to update the existing err

> >
> > > + * (3) -EINVAL when other errors occur.
> > > + */
> > >  static int __init get_cpu_for_node(struct device_node *node)
> > >  {
> > > -	struct device_node *cpu_node;
> > > +	struct device_node *cpu_node, *t;
> > >  	int cpu;
> > > +	bool found = false;
> > >
> > >  	cpu_node = of_parse_phandle(node, "cpu", 0);
> > >  	if (!cpu_node)
> > > -		return -1;
> > > +		return -EINVAL;
> > > +
> > > +	for_each_of_cpu_node(t)
> > > +		if (t == cpu_node) {
> > > +			found = true;
> > > +			break;
> > > +		}
> > > +
> > > +	if (!found) {
> > > +		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> > > +		return -EINVAL;
> > > +	}

Drop all the above change.

> > >
> > >  	cpu = of_cpu_node_to_id(cpu_node);
> > >  	if (cpu >= 0)
> > >  		topology_parse_cpu_capacity(cpu_node, cpu);

You can add here: else if (cpu == -ENODEV)
	pr_info(...whatever you have below..)

Other things as is. Warning may be too harsh if one is running with
reduced number of CPUs.

> > >  	else
> > > -		pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> > > +		pr_warn("CPU node for %pOF exist but the possible cpu range
> > is :%*pbl\n",
> > > +			cpu_node, cpumask_pr_args(cpu_possible_mask));
> > >
> > > -	of_node_put(cpu_node);
> >
> > Why is this dropped ?
>
> It's unnecessary here since no one get the node ref.
>

Please read the description of of_parse_phandle. If you find other
issues with existing code, address it in separate patch and don't mix
with the issue in $subject.

--
Regards,
Sudeep

RE: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Zengtao (B)]

> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> Sent: Monday, January 13, 2020 8:21 PM
> To: Zengtao (B)
> Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu
> nodes
> 
> On Mon, Jan 13, 2020 at 12:06:11PM +0000, Zengtao (B) wrote:
> > > -----Original Message-----
> > > From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> > > Sent: Monday, January 13, 2020 6:19 PM
> > > To: Zengtao (B)
> > > Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible
> cpu
> > > nodes
> > >
> > > On Sat, Jan 11, 2020 at 02:53:40PM +0800, Zeng Tao wrote:
> > > > When CONFIG_NR_CPUS is smaller than the cpu nodes defined in
> the
> > > device
> > > > tree, all the cpu nodes parsing will fail.
> > > > And this is not reasonable for a legal device tree configs.
> > > > In this patch, skip such cpu nodes rather than return an error.
> > > > With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree
> is
> > > 130,
> > > > The following warning messages will be print during boot:
> > > > CPU node for /cpus/cpu@128 exist but the possible cpu range
> > > is :0-127
> > > > CPU node for /cpus/cpu@129 exist but the possible cpu range
> > > is :0-127
> > > > CPU node for /cpus/cpu@130 exist but the possible cpu range
> > > is :0-127
> > > >
> > > > Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
> > > > ---
> > > > Changelog:
> > > > v1->v2:
> > > >  -Remove redundant -ENODEV assignment in get_cpu_for_node
> > > >  -Add comment to describe the get_cpu_for_node return values
> > > >  -Add skip process for cpu threads
> > > >  -Update the commit log with more detail
> > > > ---
> > > >  drivers/base/arch_topology.c | 37
> > > +++++++++++++++++++++++++++++--------
> > > >  1 file changed, 29 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/drivers/base/arch_topology.c
> > > b/drivers/base/arch_topology.c
> > > > index 5fe44b3..01f0e21 100644
> > > > --- a/drivers/base/arch_topology.c
> > > > +++ b/drivers/base/arch_topology.c
> > > > @@ -248,22 +248,44 @@ core_initcall(free_raw_capacity);
> > > >  #endif
> > > >
> > > >  #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV)
> > > > +/*
> > > > + * This function returns the logic cpu number of the node.
> > > > + * There are totally three kinds of return values:
> > > > + * (1) logic cpu number which is > 0.
> > > > + * (2) -ENDEV when the node is valid one which can be found in
> the
> > > device tree
> > > > + * but there is no possible cpu nodes to match, when the
> > > CONFIG_NR_CPUS is
> > > > + * smaller than cpus node numbers in device tree, this will
> happen.
> > > It's
> > > > + * suggested to just ignore this case.
> > >
> > > s/ENDEV/ENODEV/
> > Good catch, thanks.
> >
> > >
> > > Also as I mentioned earlier, I prefer not to add any extra logic here
> > > other than the above comment to make it explicit. This triggers
> > > unnecessary
> > > warnings when someone boots with limited CPUs for valid reasons.
> > >
> >
> > So , what 's your suggestion here? Just keep the comments but remove
> >  the warning message print?
> 
> Yes for all the "found" logic. I am fine to update the existing err
> 

Find, I will take it.
.
> > >
> > > > + * (3) -EINVAL when other errors occur.
> > > > + */
> > > >  static int __init get_cpu_for_node(struct device_node *node)
> > > >  {
> > > > -	struct device_node *cpu_node;
> > > > +	struct device_node *cpu_node, *t;
> > > >  	int cpu;
> > > > +	bool found = false;
> > > >
> > > >  	cpu_node = of_parse_phandle(node, "cpu", 0);
> > > >  	if (!cpu_node)
> > > > -		return -1;
> > > > +		return -EINVAL;
> > > > +
> > > > +	for_each_of_cpu_node(t)
> > > > +		if (t == cpu_node) {
> > > > +			found = true;
> > > > +			break;
> > > > +		}
> > > > +
> > > > +	if (!found) {
> > > > +		pr_crit("Unable to find CPU node for %pOF\n",
> cpu_node);
> > > > +		return -EINVAL;
> > > > +	}
> 
> Drop all the above change.

Could you help to explain here?
I understand there are two abnormal cases:
1. The cpu node exist in the device tree, but not a possible cpu.
This case can be caught by of_cpu_node_to_id's return value.
2. The cpu node does not exist.
This case can be caught by above logic. Or do you think 
of_parse_phandle's return value is enough? 

> 
> > > >
> > > >  	cpu = of_cpu_node_to_id(cpu_node);
> > > >  	if (cpu >= 0)
> > > >  		topology_parse_cpu_capacity(cpu_node, cpu);
> 
> You can add here: else if (cpu == -ENODEV)
> 	pr_info(...whatever you have below..)
> 
> Other things as is. Warning may be too harsh if one is running with
> reduced number of CPUs.
> 
> > > >  	else
> > > > -		pr_crit("Unable to find CPU node for %pOF\n",
> cpu_node);
> > > > +		pr_warn("CPU node for %pOF exist but the possible cpu
> range
> > > is :%*pbl\n",
> > > > +			cpu_node, cpumask_pr_args(cpu_possible_mask));
> > > >
> > > > -	of_node_put(cpu_node);
> > >
> > > Why is this dropped ?
> >
> > It's unnecessary here since no one get the node ref.
> >
> 
> Please read the description of of_parse_phandle. If you find other
> issues with existing code, address it in separate patch and don't mix
> with the issue in $subject.
> 
^_^, got it , will remove, Thanks

Regards
Zengtao 

Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Sudeep Holla]

On Tue, Jan 14, 2020 at 01:42:25AM +0000, Zengtao (B) wrote:
> Could you help to explain here?
> I understand there are two abnormal cases:
> 1. The cpu node exist in the device tree, but not a possible cpu.
> This case can be caught by of_cpu_node_to_id's return value.

Yes if of_cpu_node_to_id returns -ENODEV, it means there's no logical
CPU associated with this DT node.

> 2. The cpu node does not exist. This case can be caught by above logic. Or
> do you think of_parse_phandle's return value is enough?

Again yes, there's nothing extra needed.

The only change you need is to consider -ENODEV while handling the case(1)

--
Regards,
Sudeep

RE: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Zengtao (B)]

> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@arm.com]
> Sent: Tuesday, January 14, 2020 6:30 PM
> To: Zengtao (B)
> Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki;
> linux-kernel@vger.kernel.org; Sudeep Holla
> Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu
> nodes
> 
> On Tue, Jan 14, 2020 at 01:42:25AM +0000, Zengtao (B) wrote:
> > Could you help to explain here?
> > I understand there are two abnormal cases:
> > 1. The cpu node exist in the device tree, but not a possible cpu.
> > This case can be caught by of_cpu_node_to_id's return value.
> 
> Yes if of_cpu_node_to_id returns -ENODEV, it means there's no logical
> CPU associated with this DT node.
> 
> > 2. The cpu node does not exist. This case can be caught by above logic.
> Or
> > do you think of_parse_phandle's return value is enough?
> 
> Again yes, there's nothing extra needed.
> 
> The only change you need is to consider -ENODEV while handling the
> case(1)
> 
Thanks very much for your explanation.
So finally it turns into a very simple patch like this, more cleaner:
+/*
+ * This function returns the logic cpu number of the node.
+ * There are basically three kinds of return values:
+ * (1) logic cpu number which is > 0.
+ * (2) -ENDEV when the node is valid one which can be found in the device tree
+ * but there is no possible cpu nodes to match, when the CONFIG_NR_CPUS is
+ * smaller than cpus node numbers in device tree, this will happen. It's
+ * suggested to just ignore this case.
+ * (3) -1 if the node does not exist in the device tree
+ */
 static int __init get_cpu_for_node(struct device_node *node)
 {
        struct device_node *cpu_node;
@@ -261,7 +271,8 @@ static int __init get_cpu_for_node(struct device_node *node)
        if (cpu >= 0)
                topology_parse_cpu_capacity(cpu_node, cpu);
        else
-               pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
+               pr_info("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
+                       cpu_node, cpumask_pr_args(cpu_possible_mask));

        of_node_put(cpu_node);
        return cpu;
@@ -286,9 +297,8 @@ static int __init parse_core(struct device_node *core, int package_id,
                                cpu_topology[cpu].package_id = package_id;
                                cpu_topology[cpu].core_id = core_id;
                                cpu_topology[cpu].thread_id = i;
-                       } else {
-                               pr_err("%pOF: Can't get CPU for thread\n",
-                                      t);
+                       } else if (cpu != -ENODEV) {
+                               pr_err("%pOF: Can't get CPU for thread\n", t);
                                of_node_put(t);
                                return -EINVAL;
                        }
@@ -307,7 +317,7 @@ static int __init parse_core(struct device_node *core, int package_id,

                cpu_topology[cpu].package_id = package_id;
                cpu_topology[cpu].core_id = core_id;
-       } else if (leaf) {
+       } else if (leaf && cpu != -ENODEV) {
                pr_err("%pOF: Can't get CPU for leaf core\n", core);
                return -EINVAL;
        }

Any more suggestions? 

Regards
Zengtao 

Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes

[Sudeep Holla]

On Tue, Jan 14, 2020 at 12:17:41PM +0000, Zengtao (B) wrote:
[...]

> Thanks very much for your explanation.
> So finally it turns into a very simple patch like this, more cleaner:
> +/*
> + * This function returns the logic cpu number of the node.
> + * There are basically three kinds of return values:
> + * (1) logic cpu number which is > 0.
> + * (2) -ENDEV when the node is valid one which can be found in the device tree

s/ENDEV/ENODEV/ again :)

> + * but there is no possible cpu nodes to match, when the CONFIG_NR_CPUS is
> + * smaller than cpus node numbers in device tree, this will happen. It's
> + * suggested to just ignore this case.
> + * (3) -1 if the node does not exist in the device tree
> + */
>  static int __init get_cpu_for_node(struct device_node *node)
>  {
>         struct device_node *cpu_node;
> @@ -261,7 +271,8 @@ static int __init get_cpu_for_node(struct device_node *node)
>         if (cpu >= 0)
>                 topology_parse_cpu_capacity(cpu_node, cpu);
>         else
> -               pr_crit("Unable to find CPU node for %pOF\n", cpu_node);
> +               pr_info("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
> +                       cpu_node, cpumask_pr_args(cpu_possible_mask));
> 
>         of_node_put(cpu_node);
>         return cpu;
> @@ -286,9 +297,8 @@ static int __init parse_core(struct device_node *core, int package_id,
>                                 cpu_topology[cpu].package_id = package_id;
>                                 cpu_topology[cpu].core_id = core_id;
>                                 cpu_topology[cpu].thread_id = i;
> -                       } else {
> -                               pr_err("%pOF: Can't get CPU for thread\n",
> -                                      t);
> +                       } else if (cpu != -ENODEV) {
> +                               pr_err("%pOF: Can't get CPU for thread\n", t);
>                                 of_node_put(t);
>                                 return -EINVAL;
>                         }
> @@ -307,7 +317,7 @@ static int __init parse_core(struct device_node *core, int package_id,
> 
>                 cpu_topology[cpu].package_id = package_id;
>                 cpu_topology[cpu].core_id = core_id;
> -       } else if (leaf) {
> +       } else if (leaf && cpu != -ENODEV) {
>                 pr_err("%pOF: Can't get CPU for leaf core\n", core);
>                 return -EINVAL;
>         }
> 
> Any more suggestions?

None except the above minor nit. I will wait for v3 before I give ack/review
tag. Thanks for the patience.

--
Regards,
Sudeep