linux-kernel - Re: [PATCH] driver core: Add missing pm_runtime_put

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Message-ID: <CAJZ5v0heMSa82qSVrrjrv2ioz5y-18rCKThjbPBACJ6xuXQQQg@mail.gmail.com>
Date:   Mon, 17 Jan 2022 15:01:54 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Yongzhi Liu <lyz_cs@....edu.cn>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] driver core: Add missing pm_runtime_put_noidle

On Mon, Jan 17, 2022 at 12:08 PM Yongzhi Liu <lyz_cs@....edu.cn> wrote:
>
> pm_runtime_get_noresume() in device_shutdown increments the
> runtime PM usage counter,

This is on purpose, to prevent devices from being runtime-suspended
after their shutdown callbacks have run.

> thus a matching decrement is needed

No, it is not, AFAICS.

> to keep the counter balanced.
>
> Signed-off-by: Yongzhi Liu <lyz_cs@....edu.cn>
> ---
>  drivers/base/core.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index fd034d7..29950bd 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -4523,6 +4523,8 @@ void device_shutdown(void)
>                         dev->driver->shutdown(dev);
>                 }
>
> +               pm_runtime_put_noidle(dev);
> +
>                 device_unlock(dev);
>                 if (parent)
>                         device_unlock(parent);
> --
> 2.7.4
>