On Tue, 24 May 2011 07:33:33 -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@xxxxxxxxxxxx>
> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Cc: Durgadoss R <durgadoss.r@xxxxxxxxx>
> ---
> v2: Clarified comments based on review feedback
Acked-by: Jean Delvare <khali@xxxxxxxxxxxx>
>
> 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..5773235 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 are the same).
> + * Skip if a HT sibling of this core is already registered.
> + * 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 HT sibling of a core is taken offline, but another 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;
> }
> }
--
Jean Delvare
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