ACPI: LPIT: move to use bus_get_dev_root()

Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.

Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20230322083646.2937580-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
index 3843d25..c5598b6 100644 (file)
--- a/drivers/acpi/acpi_lpit.c
+++ b/drivers/acpi/acpi_lpit.c
@@ -98,6 +98,12 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
 static void lpit_update_residency(struct lpit_residency_info *info,
                                 struct acpi_lpit_native *lpit_native)
 {
+       struct device *dev_root = bus_get_dev_root(&cpu_subsys);
+
+       /* Silently fail, if cpuidle attribute group is not present */
+       if (!dev_root)
+               return;
+
        info->frequency = lpit_native->counter_frequency ?
                                lpit_native->counter_frequency : tsc_khz * 1000;
        if (!info->frequency)
@@ -108,18 +114,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
                info->iomem_addr = ioremap(info->gaddr.address,
                                                   info->gaddr.bit_width / 8);
                if (!info->iomem_addr)
-                       return;
+                       goto exit;
 
-               /* Silently fail, if cpuidle attribute group is not present */
-               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
+               sysfs_add_file_to_group(&dev_root->kobj,
                                        &dev_attr_low_power_idle_system_residency_us.attr,
                                        "cpuidle");
        } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
-               /* Silently fail, if cpuidle attribute group is not present */
-               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
+               sysfs_add_file_to_group(&dev_root->kobj,
                                        &dev_attr_low_power_idle_cpu_residency_us.attr,
                                        "cpuidle");
        }
+exit:
+       put_device(dev_root);
 }
 
 static void lpit_process(u64 begin, u64 end)