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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Fri, 23 Sep 2022 15:25:23 +0200
Message-ID: <CAPDyKFpVMnxCd9bMg=Wd7_TpSsNM6699NG0QLz8q=KWXk9G9hw@mail.gmail.com>
Subject: Re: [PATCH] PM: runtime: Return -EINPROGRESS from rpm_resume() in the
 RPM_NOWAIT case
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     Linux PM <linux-pm@vger.kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>
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On Thu, 22 Sept 2022 at 20:04, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> The prospective callers of rpm_resume() passing RPM_NOWAIT to it may
> be confused when it returns 0 without actually resuming the device
> which may happen if the device is suspending at the given time and it
> will only resume when the suspend in progress has completed.  To avoid
> that confusion, return -EINPROGRESS from rpm_resume() in that case.
>
> Since none of the current callers passing RPM_NOWAIT to rpm_resume()
> check its return value, this change has no functional impact.

Sounds like there are additional improvements that can be made around
this, right?

>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Looks good to me!

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>  drivers/base/power/runtime.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -792,10 +792,13 @@ static int rpm_resume(struct device *dev
>                 DEFINE_WAIT(wait);
>
>                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
> -                       if (dev->power.runtime_status == RPM_SUSPENDING)
> +                       if (dev->power.runtime_status == RPM_SUSPENDING) {
>                                 dev->power.deferred_resume = true;
> -                       else
> +                               if (rpmflags & RPM_NOWAIT)
> +                                       retval = -EINPROGRESS;
> +                       } else {
>                                 retval = -EINPROGRESS;
> +                       }
>                         goto out;
>                 }
>
>
>
>