On 09-04-17, 13:45, Chen Yu wrote:
> There is a report that after
> commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine"),
> the normal CPU offline/online cycle failed on some platforms.
> According to the ftrace result, this problem was triggered on
> platforms using acpi-freq as the default cpufreq driver,
> and due to the lack of some ACPI freq method(_PCT eg), the
> cpufreq_online failed and returned a negative value, thus the CPU
> hotplug statemachine rollbacked the CPU online process. Actually
> from the user's perspective the failure of cpufreq_online should
> not prevent that CPU from being brought up, although cpufreq might
> not work on that CPU. BTW, during system bootup the cpufreq_online
> is not invoked via cpuhotplug statemachine but by the cpufreq device
> creation process, thus the APs can be brought up although cpufreq_online
> failed in that stage.
>
> This patch ignores the return value of cpufreq_online/offline and
> let the cpufreq framework to deal with the failure that, cpufreq_online()
> will do a proper rollback in that case. And if the _PCT is missing,
> the acpi cpufreq driver will print a warning if the corresponding
> debug options have been enabled.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=194581
> Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
> Reported-and-tested-by: Tomasz Maciej Nowak <tmn505@xxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Cc: linux-pm@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Stable <stable@xxxxxxxxxxxxxxx> # 4.9+
> Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> ---
> v2:
> - According to Rafael and Sebastian's suggestion, remove
> the error log in cpuhp_cpufreq_online/offline, and let
> the cpufreq_online and cpufreq_offline to print the warning
> and do the necessary rollback if they failed.
> ---
> drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index bc96d42..0e3f649 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2398,6 +2398,20 @@ EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
> *********************************************************************/
> static enum cpuhp_state hp_online;
>
> +static int cpuhp_cpufreq_online(unsigned int cpu)
> +{
> + cpufreq_online(cpu);
> +
> + return 0;
> +}
> +
> +static int cpuhp_cpufreq_offline(unsigned int cpu)
> +{
> + cpufreq_offline(cpu);
> +
> + return 0;
> +}
> +
> /**
> * cpufreq_register_driver - register a CPU Frequency driver
> * @driver_data: A struct cpufreq_driver containing the values#
> @@ -2460,8 +2474,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> }
>
> ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online",
> - cpufreq_online,
> - cpufreq_offline);
> + cpuhp_cpufreq_online,
> + cpuhp_cpufreq_offline);
> if (ret < 0)
> goto err_if_unreg;
> hp_online = ret;
Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
--
viresh