On Tuesday, June 23, 2020 8:31:52 AM CEST Chen Yu wrote:
> Currently s2idle is a little different from the normal idle path. This
> patch makes call_s2idle() consistent with call_cpuidle(), and also
> s2idle_enter() is analogous to cpuidle_enter().
> 
> No functional change.
> 
> Suggested-by: Peter Zijlstra (Intel) <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Len Brown <[email protected]>
> Cc: Peter Zijlstra (Intel) <[email protected]>
> Signed-off-by: Chen Yu <[email protected]>
> ---
>  drivers/cpuidle/cpuidle.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index e092789187c6..b2e764d1ac99 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -134,8 +134,8 @@ int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
>  }
>  
>  #ifdef CONFIG_SUSPEND
> -static void enter_s2idle_proper(struct cpuidle_driver *drv,
> -                             struct cpuidle_device *dev, int index)
> +static void s2idle_enter(struct cpuidle_driver *drv,
> +                      struct cpuidle_device *dev, int index)
>  {
>       ktime_t time_start, time_end;
>  
> @@ -169,6 +169,15 @@ static void enter_s2idle_proper(struct cpuidle_driver 
> *drv,
>       dev->states_usage[index].s2idle_usage++;
>  }
>  
> +static int call_s2idle(struct cpuidle_driver *drv,
> +                    struct cpuidle_device *dev, int index)
> +{
> +     if (!current_clr_polling_and_test())
> +             s2idle_enter(drv, dev, index);
> +

Well, I'd rather move the definition of this function to idle.c, because it is
better to call current_clr_polling_and_test() from there.

> +     return index;
> +}
> +
>  /**
>   * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
>   * @drv: cpuidle driver for the given CPU.
> @@ -187,8 +196,8 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, 
> struct cpuidle_device *dev)
>        * be frozen safely.
>        */
>       index = find_deepest_state(drv, dev, U64_MAX, 0, true);
> -     if (index > 0 && !current_clr_polling_and_test())
> -             enter_s2idle_proper(drv, dev, index);
> +     if (index > 0)
> +             call_s2idle(drv, dev, index);

This can be made look more like cpuidle_enter() too.

>  
>       return index;
>  }
> 

So overall I'd prefer to apply something like this (on top of the [1/2]):

---
From: Rafael J. Wysocki <[email protected]>
Subject: [PATCH] cpuidle: Rearrange s2idle-specific idle state entry code

Implement call_cpuidle_s2idle() in analogy with call_cpuidle()
for the s2idle-specific idle state entry and invoke it from
cpuidle_idle_call() to make the s2idle-specific idle entry code
path look more similar to the "regular" idle entry one.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <[email protected]>
---
 drivers/cpuidle/cpuidle.c |    6 +++---
 kernel/sched/idle.c       |   15 +++++++++++----
 2 files changed, 14 insertions(+), 7 deletions(-)

Index: linux-pm/kernel/sched/idle.c
===================================================================
--- linux-pm.orig/kernel/sched/idle.c
+++ linux-pm/kernel/sched/idle.c
@@ -96,6 +96,15 @@ void __cpuidle default_idle_call(void)
        }
 }
 
+static int call_cpuidle_s2idle(struct cpuidle_driver *drv,
+                              struct cpuidle_device *dev)
+{
+       if (current_clr_polling_and_test())
+               return -EBUSY;
+
+       return cpuidle_enter_s2idle(drv, dev);
+}
+
 static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
                      int next_state)
 {
@@ -171,11 +180,9 @@ static void cpuidle_idle_call(void)
                if (idle_should_enter_s2idle()) {
                        rcu_idle_enter();
 
-                       entered_state = cpuidle_enter_s2idle(drv, dev);
-                       if (entered_state > 0) {
-                               local_irq_enable();
+                       entered_state = call_cpuidle_s2idle(drv, dev);
+                       if (entered_state > 0)
                                goto exit_idle;
-                       }
 
                        rcu_idle_exit();
 
Index: linux-pm/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.c
+++ linux-pm/drivers/cpuidle/cpuidle.c
@@ -13,7 +13,6 @@
 #include <linux/mutex.h>
 #include <linux/sched.h>
 #include <linux/sched/clock.h>
-#include <linux/sched/idle.h>
 #include <linux/notifier.h>
 #include <linux/pm_qos.h>
 #include <linux/cpu.h>
@@ -187,9 +186,10 @@ int cpuidle_enter_s2idle(struct cpuidle_
         * be frozen safely.
         */
        index = find_deepest_state(drv, dev, U64_MAX, 0, true);
-       if (index > 0 && !current_clr_polling_and_test())
+       if (index > 0) {
                enter_s2idle_proper(drv, dev, index);
-
+               local_irq_enable();
+       }
        return index;
 }
 #endif /* CONFIG_SUSPEND */



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