From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit 65650b35133ff20f0c9ef0abd5c3c66dbce3ae57 upstream.
It is incorrect to set the cpufreq syscore shutdown callback pointer to cpufreq_suspend(), because that function cannot be run in the syscore stage of system shutdown for two reasons: (a) it may attempt to carry out actions depending on devices that have already been shut down at that point and (b) the RCU synchronization carried out by it may not be able to make progress then.
The latter issue has been present since commit 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds"), but the former one has been there since commit 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") regardless.
Fix that by dropping cpufreq_syscore_ops altogether and making device_shutdown() call cpufreq_suspend() directly before shutting down devices, which is along the lines of what system-wide power management does.
Fixes: 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Fixes: 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") Reported-by: Ville Syrjälä ville.syrjala@linux.intel.com Tested-by: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Viresh Kumar viresh.kumar@linaro.org Cc: 4.0+ stable@vger.kernel.org # 4.0+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/base/core.c | 3 +++ drivers/cpufreq/cpufreq.c | 10 ---------- 2 files changed, 3 insertions(+), 10 deletions(-)
--- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -9,6 +9,7 @@ */
#include <linux/acpi.h> +#include <linux/cpufreq.h> #include <linux/device.h> #include <linux/err.h> #include <linux/fwnode.h> @@ -3150,6 +3151,8 @@ void device_shutdown(void) wait_for_device_probe(); device_block_probing();
+ cpufreq_suspend(); + spin_lock(&devices_kset->list_lock); /* * Walk the devices list backward, shutting down each in turn. --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2746,14 +2746,6 @@ int cpufreq_unregister_driver(struct cpu } EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
-/* - * Stop cpufreq at shutdown to make sure it isn't holding any locks - * or mutexes when secondary CPUs are halted. - */ -static struct syscore_ops cpufreq_syscore_ops = { - .shutdown = cpufreq_suspend, -}; - struct kobject *cpufreq_global_kobject; EXPORT_SYMBOL(cpufreq_global_kobject);
@@ -2765,8 +2757,6 @@ static int __init cpufreq_core_init(void cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj); BUG_ON(!cpufreq_global_kobject);
- register_syscore_ops(&cpufreq_syscore_ops); - return 0; } module_param(off, int, 0444);