diff mbox series

[V4,2/4] cpufreq: intel_pstate: Migrate to ->offline() instead of ->stop_cpu()

Message ID 6144911f36d3d1f5faddf81d744bd39946843f6b.1624421816.git.viresh.kumar@linaro.org (mailing list archive)
State Superseded, archived
Headers show
Series cpufreq: Migrate away from ->stop_cpu() callback | expand

Commit Message

Viresh Kumar June 23, 2021, 4:24 a.m. UTC 
commit 367dc4aa932b ("cpufreq: Add stop CPU callback to cpufreq_driver
interface") added the stop_cpu() callback to allow the drivers to do
clean up before the CPU is completely down and its state can't be
modified.

At that time the CPU hotplug framework used to call the cpufreq core's
registered notifier for different events like CPU_DOWN_PREPARE and
CPU_POST_DEAD. The stop_cpu() callback was called during the
CPU_DOWN_PREPARE event.

This is no longer the case, cpuhp_cpufreq_offline() is called only once
by the CPU hotplug core now and we don't really need to separately
call stop_cpu() for cpufreq drivers.

Migrate to using the offline() callbacks instead of stop_cpu().

Cc: Dirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/intel_pstate.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

Comments

Rafael J. Wysocki June 23, 2021, 3:13 p.m. UTC | #1 
On Wednesday, June 23, 2021 6:24:40 AM CEST Viresh Kumar wrote:
> commit 367dc4aa932b ("cpufreq: Add stop CPU callback to cpufreq_driver
> interface") added the stop_cpu() callback to allow the drivers to do
> clean up before the CPU is completely down and its state can't be
> modified.
> 
> At that time the CPU hotplug framework used to call the cpufreq core's
> registered notifier for different events like CPU_DOWN_PREPARE and
> CPU_POST_DEAD. The stop_cpu() callback was called during the
> CPU_DOWN_PREPARE event.
> 
> This is no longer the case, cpuhp_cpufreq_offline() is called only once
> by the CPU hotplug core now and we don't really need to separately
> call stop_cpu() for cpufreq drivers.
> 
> Migrate to using the offline() callbacks instead of stop_cpu().
> 
> Cc: Dirk Brandewie <dirk.brandewie@gmail.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/intel_pstate.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 0e69dffd5a76..b4c0ff7f5b71 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -2335,6 +2335,8 @@ static int intel_pstate_cpu_offline(struct cpufreq_policy *policy)
>  
>  	pr_debug("CPU %d going offline\n", cpu->cpu);
>  
> +	intel_pstate_clear_update_util_hook(policy->cpu);

As mentioned already in

https://lore.kernel.org/linux-pm/CAJZ5v0g2tCZptcqh+c55YYiO7rDHmZivMLsmpq_7005zNPN1xg@mail.gmail.com/

this isn't particularly clean, because intel_pstate_cpu_offline() is
also used in the passive mode where the above call is not needed.

I would make a change like in the patch below instead.

> +
>  	if (cpu->suspended)
>  		return 0;

---
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Subject: [PATCH] cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline()

Combine the ->stop_cpu() and ->offline() callback routines for the
active mode of intel_pstate so as to avoid setting the ->stop_cpu
callback pointer which is going to be dropped from the framework.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/intel_pstate.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -2577,11 +2577,13 @@ static int intel_pstate_cpu_online(struc
 	return 0;
 }
 
-static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
+static int intel_pstate_stop_cpu(struct cpufreq_policy *policy)
 {
 	pr_debug("CPU %d stopping\n", policy->cpu);
 
 	intel_pstate_clear_update_util_hook(policy->cpu);
+
+	return intel_pstate_cpu_offline(policy);
 }
 
 static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
@@ -2654,8 +2656,7 @@ static struct cpufreq_driver intel_pstat
 	.resume		= intel_pstate_resume,
 	.init		= intel_pstate_cpu_init,
 	.exit		= intel_pstate_cpu_exit,
-	.stop_cpu	= intel_pstate_stop_cpu,
-	.offline	= intel_pstate_cpu_offline,
+	.offline	= intel_pstate_stop_cpu,
 	.online		= intel_pstate_cpu_online,
 	.update_limits	= intel_pstate_update_limits,
 	.name		= "intel_pstate",
Viresh Kumar June 24, 2021, 1:52 a.m. UTC | #2 
On 23-06-21, 17:13, Rafael J. Wysocki wrote:
> As mentioned already in
> 
> https://lore.kernel.org/linux-pm/CAJZ5v0g2tCZptcqh+c55YYiO7rDHmZivMLsmpq_7005zNPN1xg@mail.gmail.com/

Sorry about failing to reply over that, I got confused somehow..

> this isn't particularly clean, because intel_pstate_cpu_offline() is
> also used in the passive mode where the above call is not needed.

intel_pstate_clear_update_util_hook() returns early if the hook was never
registered, and so calling it was safe, but yes not very clean.

> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline()
> 
> Combine the ->stop_cpu() and ->offline() callback routines for the
> active mode of intel_pstate so as to avoid setting the ->stop_cpu
> callback pointer which is going to be dropped from the framework.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/cpufreq/intel_pstate.c |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -2577,11 +2577,13 @@ static int intel_pstate_cpu_online(struc
>  	return 0;
>  }
>  
> -static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
> +static int intel_pstate_stop_cpu(struct cpufreq_policy *policy)
>  {
>  	pr_debug("CPU %d stopping\n", policy->cpu);
>  
>  	intel_pstate_clear_update_util_hook(policy->cpu);
> +
> +	return intel_pstate_cpu_offline(policy);
>  }
>  
>  static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
> @@ -2654,8 +2656,7 @@ static struct cpufreq_driver intel_pstat
>  	.resume		= intel_pstate_resume,
>  	.init		= intel_pstate_cpu_init,
>  	.exit		= intel_pstate_cpu_exit,
> -	.stop_cpu	= intel_pstate_stop_cpu,
> -	.offline	= intel_pstate_cpu_offline,
> +	.offline	= intel_pstate_stop_cpu,

I would suggest to rename intel_pstate_cpu_offline() as
intel_cpufreq_cpu_offline() and intel_pstate_stop_cpu() as
intel_pstate_cpu_offline(), so we remove the stop-cpu terminology completely.

Either way:
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

>  	.online		= intel_pstate_cpu_online,
>  	.update_limits	= intel_pstate_update_limits,
>  	.name		= "intel_pstate",
Rafael J. Wysocki June 30, 2021, 4:58 p.m. UTC | #3 
On Thu, Jun 24, 2021 at 3:52 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 23-06-21, 17:13, Rafael J. Wysocki wrote:
> > As mentioned already in
> >
> > https://lore.kernel.org/linux-pm/CAJZ5v0g2tCZptcqh+c55YYiO7rDHmZivMLsmpq_7005zNPN1xg@mail.gmail.com/
>
> Sorry about failing to reply over that, I got confused somehow..
>
> > this isn't particularly clean, because intel_pstate_cpu_offline() is
> > also used in the passive mode where the above call is not needed.
>
> intel_pstate_clear_update_util_hook() returns early if the hook was never
> registered, and so calling it was safe, but yes not very clean.
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Subject: [PATCH] cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline()
> >
> > Combine the ->stop_cpu() and ->offline() callback routines for the
> > active mode of intel_pstate so as to avoid setting the ->stop_cpu
> > callback pointer which is going to be dropped from the framework.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  drivers/cpufreq/intel_pstate.c |    7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > Index: linux-pm/drivers/cpufreq/intel_pstate.c
> > ===================================================================
> > --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> > +++ linux-pm/drivers/cpufreq/intel_pstate.c
> > @@ -2577,11 +2577,13 @@ static int intel_pstate_cpu_online(struc
> >       return 0;
> >  }
> >
> > -static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
> > +static int intel_pstate_stop_cpu(struct cpufreq_policy *policy)
> >  {
> >       pr_debug("CPU %d stopping\n", policy->cpu);
> >
> >       intel_pstate_clear_update_util_hook(policy->cpu);
> > +
> > +     return intel_pstate_cpu_offline(policy);
> >  }
> >
> >  static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
> > @@ -2654,8 +2656,7 @@ static struct cpufreq_driver intel_pstat
> >       .resume         = intel_pstate_resume,
> >       .init           = intel_pstate_cpu_init,
> >       .exit           = intel_pstate_cpu_exit,
> > -     .stop_cpu       = intel_pstate_stop_cpu,
> > -     .offline        = intel_pstate_cpu_offline,
> > +     .offline        = intel_pstate_stop_cpu,
>
> I would suggest to rename intel_pstate_cpu_offline() as
> intel_cpufreq_cpu_offline() and intel_pstate_stop_cpu() as
> intel_pstate_cpu_offline(), so we remove the stop-cpu terminology completely.

I have followed the above suggestion and applied the modified patch
along with the rest of this series.

> Either way:
> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

Thanks!

> >       .online         = intel_pstate_cpu_online,
> >       .update_limits  = intel_pstate_update_limits,
> >       .name           = "intel_pstate",
diff mbox series

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 0e69dffd5a76..b4c0ff7f5b71 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2335,6 +2335,8 @@  static int intel_pstate_cpu_offline(struct cpufreq_policy *policy)
 
 	pr_debug("CPU %d going offline\n", cpu->cpu);
 
+	intel_pstate_clear_update_util_hook(policy->cpu);
+
 	if (cpu->suspended)
 		return 0;
 
@@ -2374,13 +2376,6 @@  static int intel_pstate_cpu_online(struct cpufreq_policy *policy)
 	return 0;
 }
 
-static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
-{
-	pr_debug("CPU %d stopping\n", policy->cpu);
-
-	intel_pstate_clear_update_util_hook(policy->cpu);
-}
-
 static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
 {
 	pr_debug("CPU %d exiting\n", policy->cpu);
@@ -2451,7 +2446,6 @@  static struct cpufreq_driver intel_pstate = {
 	.resume		= intel_pstate_resume,
 	.init		= intel_pstate_cpu_init,
 	.exit		= intel_pstate_cpu_exit,
-	.stop_cpu	= intel_pstate_stop_cpu,
 	.offline	= intel_pstate_cpu_offline,
 	.online		= intel_pstate_cpu_online,
 	.update_limits	= intel_pstate_update_limits,