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 <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> Cc: Viresh Kumar <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: Len Brown <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Stable <[email protected]> # 4.9+ Signed-off-by: Chen Yu <[email protected]> --- 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; -- 2.7.4
