linux-kernel - Re: [PATCH] drivers/cros_ec: Emergency sync filesystem on EC panic

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Message-ID: <CABXOdTf2bJMekRR9f4zyBNDEY5Uuogin-dy9HOEvWhaEW0-Qtg@mail.gmail.com>
Date:   Mon, 17 Jul 2023 16:54:00 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Rob Barnes <robbarnes@...gle.com>
Cc:     pmalani@...omium.org, chrome-platform@...ts.linux.dev,
        briannorris@...omium.org, Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/cros_ec: Emergency sync filesystem on EC panic

On Mon, Jul 17, 2023 at 4:29 PM Rob Barnes <robbarnes@...gle.com> wrote:
>
> Perform an emergency filesystem sync when an EC panic is reported. An
> emergency sync actually performs two syncs internally in case some
> inodes or pages are temporarily locked.
>
> hw_protection_shutdown is replaced for a few reasons. It is unnecessary
> because the EC will force reset either way. hw_protection_shutdown does
> not reliably sync filesystem before shutting down. emergency_sync is not
> synchronous so hw_protection_shutdown may interrupt emergency_sync.
>
> Signed-off-by: Rob Barnes <robbarnes@...gle.com>

Makes sense.

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
>
>  drivers/platform/chrome/cros_ec_lpc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index 500a61b093e47..9652fc073c2a4 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -327,8 +327,8 @@ static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
>                 dev_emerg(ec_dev->dev, "CrOS EC Panic Reported. Shutdown is imminent!");
>                 blocking_notifier_call_chain(&ec_dev->panic_notifier, 0, ec_dev);
>                 kobject_uevent_env(&ec_dev->dev->kobj, KOBJ_CHANGE, (char **)env);
> -               /* Begin orderly shutdown. Force shutdown after 1 second. */
> -               hw_protection_shutdown("CrOS EC Panic", 1000);
> +               /* Force sync the filesystem before EC resets */
> +               emergency_sync();
>                 /* Do not query for other events after a panic is reported */
>                 return;
>         }
> --
> 2.41.0.255.g8b1d071c50-goog
>