On Mon, Mar 13, 2023 at 7:29 PM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> 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: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Cc: linux-acpi@xxxxxxxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> Note, this is a patch that is a prepatory cleanup as part of a larger
> series of patches that is working on resolving some old driver core
> design mistakes. It will build and apply cleanly on top of 6.3-rc2 on
> its own, but I'd prefer if I could take it through my driver-core tree
> so that the driver core changes can be taken through there for 6.4-rc1.
>
> drivers/acpi/acpi_lpit.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
> index 3843d2576d3f..73b5c4800150 100644
> --- a/drivers/acpi/acpi_lpit.c
> +++ b/drivers/acpi/acpi_lpit.c
> @@ -98,6 +98,8 @@ 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);
> +
This can return here right away if dev_root is NULL, because it will
not do anything useful in that case anyway.
> info->frequency = lpit_native->counter_frequency ?
> lpit_native->counter_frequency : tsc_khz * 1000;
> if (!info->frequency)
> @@ -111,15 +113,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
> return;
>
> /* Silently fail, if cpuidle attribute group is not present */
> - sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
> - &dev_attr_low_power_idle_system_residency_us.attr,
> - "cpuidle");
> + if (dev_root)
> + 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,
> - &dev_attr_low_power_idle_cpu_residency_us.attr,
> - "cpuidle");
> + if (dev_root)
> + sysfs_add_file_to_group(&dev_root->kobj,
> + &dev_attr_low_power_idle_cpu_residency_us.attr,
> + "cpuidle");
> }
> + put_device(dev_root);
> }
>
> static void lpit_process(u64 begin, u64 end)
> --
> 2.39.2
>
