| Message ID | 20220128032554.155132-1-bjorn.andersson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] cpufreq: Reintroduce ready() callback | expand |
On 28-01-22, 10:30, Bjorn Andersson wrote: > On Fri 28 Jan 02:39 PST 2022, Lukasz Luba wrote: > > On 1/28/22 3:25 AM, Bjorn Andersson wrote: > > > In the event that the SoC is under thermal pressure while booting it's > > > possible for the dcvs notification to happen inbetween the cpufreq > > > framework calling init and it actually updating the policy's > > > related_cpus cpumask. > > > > > > Prior to the introduction of the thermal pressure update helper an empty > > > cpumask would simply result in the thermal pressure of no cpus being > > > updated, but the new code will attempt to dereference an invalid per_cpu > > > variable. > > > > Just to confirm, is that per-cpu var the 'policy->related_cpus' in this > > driver? > > > > Correct, we boot under thermal pressure, so the interrupt fires before > we return from "init", which means that related_cpus is still 0. Just to clarify here a bit, policy->related_cpus is already allocated at this point of time. AFAICT, the dereferencing of the invalid per-cpu variable refers to the per-cpu freq_factor in arch_topology.c, which happens because the cpumask isn't initialized yet.
On 27-01-22, 19:25, Bjorn Andersson wrote: > This effectively revert '4bf8e582119e ("cpufreq: Remove ready() > callback")' (except the Chinese translation), in order to reintroduce > the ready callback. I have added the Chinese translation back and applied both patches. Thanks.
diff --git a/Documentation/cpu-freq/cpu-drivers.rst b/Documentation/cpu-freq/cpu-drivers.rst index 3b32336a7803..d84ededb66f9 100644 --- a/Documentation/cpu-freq/cpu-drivers.rst +++ b/Documentation/cpu-freq/cpu-drivers.rst @@ -75,6 +75,9 @@ And optionally .resume - A pointer to a per-policy resume function which is called with interrupts disabled and _before_ the governor is started again. + .ready - A pointer to a per-policy ready function which is called after + the policy is fully initialized. + .attr - A pointer to a NULL-terminated list of "struct freq_attr" which allow to export values to sysfs. diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index b8d95536ee22..80f535cc8a75 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1518,6 +1518,10 @@ static int cpufreq_online(unsigned int cpu) kobject_uevent(&policy->kobj, KOBJ_ADD); + /* Callback for handling stuff after policy is ready */ + if (cpufreq_driver->ready) + cpufreq_driver->ready(policy); + if (cpufreq_thermal_control_enabled(cpufreq_driver)) policy->cdev = of_cpufreq_cooling_register(policy); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 1ab29e61b078..3522a272b74d 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -382,6 +382,9 @@ struct cpufreq_driver { int (*suspend)(struct cpufreq_policy *policy); int (*resume)(struct cpufreq_policy *policy); + /* Will be called after the driver is fully initialized */ + void (*ready)(struct cpufreq_policy *policy); + struct freq_attr **attr; /* platform specific boost support code */
This effectively revert '4bf8e582119e ("cpufreq: Remove ready() callback")' (except the Chinese translation), in order to reintroduce the ready callback. This is needed in order to be able to leave the thermal pressure interrupts in the Qualcomm CPUfreq driver disabled during initialization, so that it doesn't fire while related_cpus are still 0. Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> --- Changes since v1: - New patch Documentation/cpu-freq/cpu-drivers.rst | 3 +++ drivers/cpufreq/cpufreq.c | 4 ++++ include/linux/cpufreq.h | 3 +++ 3 files changed, 10 insertions(+)