6.8-stable review patch. If anyone has any objections, please let me know.
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From: Viresh Kumar viresh.kumar@linaro.org
[ Upstream commit c4d61a529db788d2e52654f5b02c8d1de4952c5b ]
Offlining a CPU and bringing it back online is a common operation and it happens frequently during system suspend/resume, where the non-boot CPUs are hotplugged out during suspend and brought back at resume.
The cpufreq core already tries to make this path as fast as possible as the changes are only temporary in nature and full cleanup of resources isn't required in this case. For example the drivers can implement online()/offline() callbacks to avoid a lot of tear down of resources.
On similar lines, there is no need to unregister the cpufreq cooling device during suspend / resume, but only while the policy is getting removed.
Moreover, unregistering the cpufreq cooling device is resulting in an unwanted outcome, where the system suspend is eventually aborted in the process. Currently, during system suspend the cpufreq core unregisters the cooling device, which in turn removes a kobject using device_del() and that generates a notification to the userspace via uevent broadcast. This causes system suspend to abort in some setups.
This was also earlier reported (indirectly) by Roman [1]. Maybe there is another way around to fixing that problem properly, but this change makes sense anyways.
Move the registering and unregistering of the cooling device to policy creation and removal times onlyy.
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218521 Reported-by: Manaf Meethalavalappu Pallikunhi quic_manafm@quicinc.com Reported-by: Roman Stratiienko r.stratiienko@gmail.com Link: https://patchwork.kernel.org/project/linux-pm/patch/20220710164026.541466-1-... [1] Tested-by: Manaf Meethalavalappu Pallikunhi quic_manafm@quicinc.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org Reviewed-by: Dhruva Gole d-gole@ti.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpufreq/cpufreq.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 7d570b44777ac..3c2c955fbbbd6 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1576,7 +1576,8 @@ static int cpufreq_online(unsigned int cpu) if (cpufreq_driver->ready) cpufreq_driver->ready(policy);
- if (cpufreq_thermal_control_enabled(cpufreq_driver)) + /* Register cpufreq cooling only for a new policy */ + if (new_policy && cpufreq_thermal_control_enabled(cpufreq_driver)) policy->cdev = of_cpufreq_cooling_register(policy);
pr_debug("initialization complete\n"); @@ -1660,11 +1661,6 @@ static void __cpufreq_offline(unsigned int cpu, struct cpufreq_policy *policy) else policy->last_policy = policy->policy;
- if (cpufreq_thermal_control_enabled(cpufreq_driver)) { - cpufreq_cooling_unregister(policy->cdev); - policy->cdev = NULL; - } - if (has_target()) cpufreq_exit_governor(policy);
@@ -1725,6 +1721,15 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) return; }
+ /* + * Unregister cpufreq cooling once all the CPUs of the policy are + * removed. + */ + if (cpufreq_thermal_control_enabled(cpufreq_driver)) { + cpufreq_cooling_unregister(policy->cdev); + policy->cdev = NULL; + } + /* We did light-weight exit earlier, do full tear down now */ if (cpufreq_driver->offline) cpufreq_driver->exit(policy);