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From:   Benson Leung <bleung@chromium.org>
Date:   Mon, 17 Jul 2023 16:48:19 -0700
Message-ID: <CANLzEku3vL3EKmFhN7YYdjqP=O3p4sNxtHPji2Yv8s_EMAcvRg@mail.gmail.com>
Subject: Re: [PATCH] drivers/cros_ec: Emergency sync filesystem on EC panic
To:     Rob Barnes <robbarnes@google.com>
Cc:     pmalani@chromium.org, chrome-platform@lists.linux.dev,
        briannorris@chromium.org, Guenter Roeck <groeck@chromium.org>,
        linux-kernel@vger.kernel.org, Tzung-Bi Shih <tzungbi@kernel.org>
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Hi Rob,

On Mon, Jul 17, 2023 at 4:29=E2=80=AFPM Rob Barnes <robbarnes@google.com> w=
rote:
>
> 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@google.com>

Reviewed-by: Benson Leung <bleung@chromium.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/chr=
ome/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 devic=
e, 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 reporte=
d */
>                 return;
>         }
> --
> 2.41.0.255.g8b1d071c50-goog
>


--=20
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org