linux-kernel - Re: [PATCH] PM / suspend: Abort suspend if somebody holds wakelock

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Date:   Wed, 6 Oct 2021 18:33:34 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mukesh Ojha <mojha@...eaurora.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] PM / suspend: Abort suspend if somebody holds wakelock

On Wed, Oct 6, 2021 at 6:27 PM Mukesh Ojha <mojha@...eaurora.org> wrote:
>
> There could be a scenario, where request_firmware() call results in
> user land process trying to load firmwares into memory and
> parallely one miscellaneous process is trying to invoke manual
> suspend and due to which user mode helper gets disabled during
> freezing of processes and that aborts loading of firmware even
> though request_firmware() thread has taken wakelock.
>
> Although, we are checking for any wakeup event inside
> try_to_freeze_tasks() but that could be too late for the
> above scenario.
>
> Let's add a check before freezing/disable user land process in
> suspend path.

If a laptop lid is closed and the system is expected to suspend, it
must suspend.

This takes precedence over the loading of firmware.  Sorry.

> Signed-off-by: Mukesh Ojha <mojha@...eaurora.org>
> ---
>  kernel/power/process.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index 37401c9..3e0d3d6 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -124,6 +124,9 @@ int freeze_processes(void)
>  {
>         int error;
>
> +       if (pm_wakeup_pending())
> +               return -EBUSY;
> +
>         error = __usermodehelper_disable(UMH_FREEZING);
>         if (error)
>                 return error;
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
> Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
>