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Subject[RFC][PATCH] cpufreq: intel_pstate: Delete intel_pstate sysfs if failed to register the driver
Date
There is a corner case that if the intel_pstate driver failed to be
registered(might be due to invalid MSR access) and with the acpi_cpufreq
loaded, the intel_pstate sysfs might still be created, which makes the
user confusing(turbostat for example):

grep . /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
acpi-cpufreq

grep . /sys/devices/system/cpu/intel_pstate/*
/sys/devices/system/cpu/intel_pstate/max_perf_pct:0
/sys/devices/system/cpu/intel_pstate/min_perf_pct:0
grep: /sys/devices/system/cpu/intel_pstate/no_turbo: Resource temporarily unavailable
grep: /sys/devices/system/cpu/intel_pstate/num_pstates: Resource temporarily unavailable
/sys/devices/system/cpu/intel_pstate/status:off
grep: /sys/devices/system/cpu/intel_pstate/turbo_pct: Resource temporarily unavailable

The existing of intel_pstate sysfs does not mean that the intel_pstate driver
has been successfully loaded(for example, echo off to status), but the
intel_pstate sysfs should not co-exist when acpi-cpufreq is also present.
Fix this issue by deleting the intel_pstate sysfs if the driver failed
to be loaded during bootup.

Reported-by: Wendy Wang <wendy.wang@intel.com>
Suggested-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
drivers/cpufreq/intel_pstate.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 9a515c460a00..8c5f9680de83 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1420,6 +1420,26 @@ static void __init intel_pstate_sysfs_expose_params(void)
}
}

+static void __init intel_pstate_sysfs_clean(void)
+{
+ if (!intel_pstate_kobject)
+ return;
+
+ sysfs_remove_group(intel_pstate_kobject, &intel_pstate_attr_group);
+
+ if (per_cpu_limits)
+ goto release_kobj;
+
+ sysfs_remove_file(intel_pstate_kobject, &max_perf_pct.attr);
+ sysfs_remove_file(intel_pstate_kobject, &min_perf_pct.attr);
+
+ if (x86_match_cpu(intel_pstate_cpu_ee_disable_ids))
+ sysfs_remove_file(intel_pstate_kobject, &energy_efficiency.attr);
+
+release_kobj:
+ kobject_put(intel_pstate_kobject);
+}
+
static void intel_pstate_sysfs_expose_hwp_dynamic_boost(void)
{
int rc;
@@ -3063,8 +3083,10 @@ static int __init intel_pstate_init(void)
mutex_lock(&intel_pstate_driver_lock);
rc = intel_pstate_register_driver(default_driver);
mutex_unlock(&intel_pstate_driver_lock);
- if (rc)
+ if (rc) {
+ intel_pstate_sysfs_clean();
return rc;
+ }

if (hwp_active) {
const struct x86_cpu_id *id;
--
2.17.1
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