linux-kernel - Re: [PATCH v2 3/4] PM: suspend: Assign pm_suspend_target

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Message-ID: <CAJZ5v0hEzTfZZgrgyo4NNnXj+eFrAnJgmP9Ls7kB3GM3c1V2Mw@mail.gmail.com>
Date: Wed, 2 Jul 2025 20:58:27 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Zihuan Zhang <zhangzihuan@...inos.cn>
Cc: rafael@...nel.org, pavel@...nel.org, len.brown@...el.com, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] PM: suspend: Assign pm_suspend_target_state
 earlier for valid debug logs

On Thu, Jun 19, 2025 at 5:54 AM Zihuan Zhang <zhangzihuan@...inos.cn> wrote:
>
> pm_suspend_target_state is used in debug logs inside enter_state(), but
> it is only assigned inside suspend_devices_and_enter(), which is too late.
>
> This causes early pm_pr_dbg() output to either show incorrect state or
> nothing at all, making suspend debugging harder.
>
> Assign pm_suspend_target_state at the beginning of enter_state() to ensure
> early log output is meaningful.
>
> Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
> ---
>  kernel/power/suspend.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 76b141b9aac0..16172ca22f21 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -584,6 +584,8 @@ static int enter_state(suspend_state_t state)
>         if (!mutex_trylock(&system_transition_mutex))
>                 return -EBUSY;
>
> +       pm_suspend_target_state = state;
> +
>         if (state == PM_SUSPEND_TO_IDLE)
>                 s2idle_begin();
>
> @@ -616,6 +618,7 @@ static int enter_state(suspend_state_t state)
>         suspend_finish();
>   Unlock:
>         filesystems_thaw();
> +       pm_suspend_target_state = PM_SUSPEND_ON;
>         mutex_unlock(&system_transition_mutex);
>         return error;
>  }
> --

Good catch, but you should remove the existing assignments at the same time.