Patchwork PM/runtime: Do not needlessly call ktime_get

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Submitter Ladislav Michl
Date Jan. 10, 2019, 9:51 a.m.
Message ID <20190110095125.GA4491@lenoch>
Download mbox | patch
Permalink /patch/696459/
State New
Headers show

Comments

Ladislav Michl - Jan. 10, 2019, 9:51 a.m.
pm_runtime_autosuspend_expiration calls ktime_get even when
its returned value may be unused. Therefore get current time
later and remove gotos while there.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
---
 NOTE: Depends on Vincent's "[PATCH v2] PM/runtime: Fix autosuspend_delay
       on 32bits arch"!

 drivers/base/power/runtime.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)
Tony Lindgren - Jan. 10, 2019, 4:44 p.m.
* Ladislav Michl <ladis@linux-mips.org> [190110 09:51]:
> pm_runtime_autosuspend_expiration calls ktime_get even when
> its returned value may be unused. Therefore get current time
> later and remove gotos while there.

Acked-by: Tony Lindgren <tony@atomide.com>
Vincent Guittot - Jan. 10, 2019, 6:56 p.m.
On Thu, 10 Jan 2019 at 10:51, Ladislav Michl <ladis@linux-mips.org> wrote:
>
> pm_runtime_autosuspend_expiration calls ktime_get even when
> its returned value may be unused. Therefore get current time
> later and remove gotos while there.
>
> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>

Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
>  NOTE: Depends on Vincent's "[PATCH v2] PM/runtime: Fix autosuspend_delay
>        on 32bits arch"!
>
>  drivers/base/power/runtime.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 457be03b744d..836b1b8784eb 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -129,24 +129,21 @@ static void pm_runtime_cancel_pending(struct device *dev)
>  u64 pm_runtime_autosuspend_expiration(struct device *dev)
>  {
>         int autosuspend_delay;
> -       u64 last_busy, expires = 0;
> -       u64 now = ktime_to_ns(ktime_get());
> +       u64 expires;
>
>         if (!dev->power.use_autosuspend)
> -               goto out;
> +               return 0;
>
>         autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
>         if (autosuspend_delay < 0)
> -               goto out;
> -
> -       last_busy = READ_ONCE(dev->power.last_busy);
> +               return 0;
>
> -       expires = last_busy + (u64)autosuspend_delay * NSEC_PER_MSEC;
> -       if (expires <= now)
> -               expires = 0;    /* Already expired. */
> +       expires  = READ_ONCE(dev->power.last_busy);
> +       expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
> +       if (expires > ktime_to_ns(ktime_get()))
> +               return expires; /* Expires in the future */
>
> - out:
> -       return expires;
> +       return 0;
>  }
>  EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
>
> --
> 2.20.1
>
Rafael J. Wysocki - Jan. 16, 2019, 11:57 a.m.
On Thursday, January 10, 2019 7:56:19 PM CET Vincent Guittot wrote:
> On Thu, 10 Jan 2019 at 10:51, Ladislav Michl <ladis@linux-mips.org> wrote:
> >
> > pm_runtime_autosuspend_expiration calls ktime_get even when
> > its returned value may be unused. Therefore get current time
> > later and remove gotos while there.
> >
> > Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> 
> Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

Patch applied, thanks!

Patch

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 457be03b744d..836b1b8784eb 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -129,24 +129,21 @@  static void pm_runtime_cancel_pending(struct device *dev)
 u64 pm_runtime_autosuspend_expiration(struct device *dev)
 {
 	int autosuspend_delay;
-	u64 last_busy, expires = 0;
-	u64 now = ktime_to_ns(ktime_get());
+	u64 expires;
 
 	if (!dev->power.use_autosuspend)
-		goto out;
+		return 0;
 
 	autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 	if (autosuspend_delay < 0)
-		goto out;
-
-	last_busy = READ_ONCE(dev->power.last_busy);
+		return 0;
 
-	expires = last_busy + (u64)autosuspend_delay * NSEC_PER_MSEC;
-	if (expires <= now)
-		expires = 0;	/* Already expired. */
+	expires  = READ_ONCE(dev->power.last_busy);
+	expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
+	if (expires > ktime_to_ns(ktime_get()))
+		return expires;	/* Expires in the future */
 
- out:
-	return expires;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);