[lm-sensors] [PATCH] hwmon: (coretemp) Add comments describing the

[lm-sensors] [PATCH] hwmon: (coretemp) Add comments describing the

[Guenter Roeck]

The coretemp driver provides a single set of device attributes for each physical
core of a HT CPU to avoid duplicate sensors. This functionality was introduced
with commit d883b9f0977269d519469da72faec6a7f72cb489.

Commit e40cc4bdfd4b89813f072f72bd9c7055814d3f0f extends this functionality to
register the HT sibling of a CPU which is taken offline, to ensure that
sensor attributes are provided if at least one HT sibling of a core is online.

Add comments into the code describing the functionality in some more detail.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
---
I am not completely happy with the added comments nor with the description
above, so please feel free to chime in if you have an idea for a better
description.

 drivers/hwmon/coretemp.c |   20 ++++++++++++++++++--
 1 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index a00245e..9577c43 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -506,7 +506,13 @@ static int create_core_data(struct platform_data *pdata,
 	if (attr_no > MAX_CORE_DATA - 1)
 		return -ERANGE;
 
-	/* Skip if it is a HT core, Not an error */
+	/*
+	 * Provide a single set of attributes for all HT siblings of a core
+	 * to avoid duplicate sensors (the processor ID and core ID of all
+	 * HT siblings of a core is the same).
+	 * Skip if a HT sibling of this core is already online.
+	 * This is not an error.
+	 */
 	if (pdata->core_data[attr_no] != NULL)
 		return 0;
 
@@ -763,10 +769,20 @@ static void __cpuinit put_core_offline(unsigned int cpu)
 	if (pdata->core_data[indx] && pdata->core_data[indx]->cpu = cpu)
 		coretemp_remove_core(pdata, &pdev->dev, indx);
 
-	/* Online the HT version of this core, if any */
+	/*
+	 * If a core is taken offline, but a HT sibling of the same core is
+	 * still online, register the alternate sibling. This ensures that
+	 * exactly one set of attributes is provided as long as at least one
+	 * HT sibling of a core is online.
+	 */
 	for_each_sibling(i, cpu) {
 		if (i != cpu) {
 			get_core_online(i);
+			/*
+			 * Display temperature sensor data for one HT sibling
+			 * per core only, so abort the loop after one such
+			 * sibling has been found.
+			 */
 			break;
 		}
 	}
-- 
1.7.3.1


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Re: [lm-sensors] [PATCH] hwmon: (coretemp) Add comments describing

[Jean Delvare]

Hi Guenter,

On Mon, 23 May 2011 14:05:38 -0700, Guenter Roeck wrote:
> The coretemp driver provides a single set of device attributes for each physical
> core of a HT CPU to avoid duplicate sensors. This functionality was introduced
> with commit d883b9f0977269d519469da72faec6a7f72cb489.
> 
> Commit e40cc4bdfd4b89813f072f72bd9c7055814d3f0f extends this functionality to
> register the HT sibling of a CPU which is taken offline, to ensure that
> sensor attributes are provided if at least one HT sibling of a core is online.
> 
> Add comments into the code describing the functionality in some more detail.
> 
> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Durgadoss R <durgadoss.r@intel.com>
> ---
> I am not completely happy with the added comments nor with the description
> above, so please feel free to chime in if you have an idea for a better
> description.

The comment above looks OK to me. For the in-code comments, I have a
few suggestions, see below.

> 
>  drivers/hwmon/coretemp.c |   20 ++++++++++++++++++--
>  1 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
> index a00245e..9577c43 100644
> --- a/drivers/hwmon/coretemp.c
> +++ b/drivers/hwmon/coretemp.c
> @@ -506,7 +506,13 @@ static int create_core_data(struct platform_data *pdata,
>  	if (attr_no > MAX_CORE_DATA - 1)
>  		return -ERANGE;
>  
> -	/* Skip if it is a HT core, Not an error */
> +	/*
> +	 * Provide a single set of attributes for all HT siblings of a core
> +	 * to avoid duplicate sensors (the processor ID and core ID of all
> +	 * HT siblings of a core is the same).

are the same

> +	 * Skip if a HT sibling of this core is already online.

What is relevant is that the HT sibling has already been registered
(which in turn implies that it was online.)

> +	 * This is not an error.
> +	 */
>  	if (pdata->core_data[attr_no] != NULL)
>  		return 0;
>  
> @@ -763,10 +769,20 @@ static void __cpuinit put_core_offline(unsigned int cpu)
>  	if (pdata->core_data[indx] && pdata->core_data[indx]->cpu = cpu)
>  		coretemp_remove_core(pdata, &pdev->dev, indx);
>  
> -	/* Online the HT version of this core, if any */
> +	/*
> +	 * If a core is taken offline, but a HT sibling of the same core is
> +	 * still online, register the alternate sibling. This ensures that

What is being taken offline is a HT sibling, nor a core.

> +	 * exactly one set of attributes is provided as long as at least one
> +	 * HT sibling of a core is online.
> +	 */
>  	for_each_sibling(i, cpu) {
>  		if (i != cpu) {
>  			get_core_online(i);
> +			/*
> +			 * Display temperature sensor data for one HT sibling
> +			 * per core only, so abort the loop after one such
> +			 * sibling has been found.
> +			 */
>  			break;
>  		}
>  	}


-- 
Jean Delvare

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Re: [lm-sensors] [PATCH] hwmon: (coretemp) Add comments describing

[Guenter Roeck]

Hi Jean,

On Tue, May 24, 2011 at 07:41:41AM -0400, Jean Delvare wrote:
> Hi Guenter,
> 
> On Mon, 23 May 2011 14:05:38 -0700, Guenter Roeck wrote:
> > The coretemp driver provides a single set of device attributes for each physical
> > core of a HT CPU to avoid duplicate sensors. This functionality was introduced
> > with commit d883b9f0977269d519469da72faec6a7f72cb489.
> > 
> > Commit e40cc4bdfd4b89813f072f72bd9c7055814d3f0f extends this functionality to
> > register the HT sibling of a CPU which is taken offline, to ensure that
> > sensor attributes are provided if at least one HT sibling of a core is online.
> > 
> > Add comments into the code describing the functionality in some more detail.
> > 
> > Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
> > Cc: Fenghua Yu <fenghua.yu@intel.com>
> > Cc: Durgadoss R <durgadoss.r@intel.com>
> > ---
> > I am not completely happy with the added comments nor with the description
> > above, so please feel free to chime in if you have an idea for a better
> > description.
> 
> The comment above looks OK to me. For the in-code comments, I have a
> few suggestions, see below.
> 

Turns out Linus already merged this version of the patch. I'll create an update patch 
for the changes and submit it.

Guenter

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