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
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;
}
}
--
1.7.3.1
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