linux-kernel - Re: [PATCH v3 1/2] mtd: Add flag to indicate panic

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Message-ID: <CAFLxGvwjqo27VQ092WV9=6N5RJr-M7aL0HYVWkeaCYbY3XWa1w@mail.gmail.com>
Date:   Fri, 17 May 2019 10:08:36 +0200
From:   Richard Weinberger <richard.weinberger@...il.com>
To:     Kamal Dasu <kdasu.kdev@...il.com>
Cc:     linux-mtd@...ts.infradead.org,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        LKML <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v3 1/2] mtd: Add flag to indicate panic_write

On Thu, May 16, 2019 at 6:42 PM Kamal Dasu <kdasu.kdev@...il.com> wrote:
>
> Added a flag to indicate a panic_write so that low level drivers can
> use it to take required action where applicable, to ensure oops data
> gets written to assigned mtd device.
>
> Signed-off-by: Kamal Dasu <kdasu.kdev@...il.com>
> ---
>  drivers/mtd/mtdcore.c   | 3 +++
>  include/linux/mtd/mtd.h | 6 ++++++
>  2 files changed, 9 insertions(+)
>
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 76b4264..a83decd 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -1138,6 +1138,9 @@ int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
>                 return -EROFS;
>         if (!len)
>                 return 0;
> +       if (!mtd->oops_panic_write)
> +               mtd->oops_panic_write = true;
> +

You can set the flag unconditionally.
If it is set, it will stay so, and setting it again, won't hurt.

>         return mtd->_panic_write(mtd, to, len, retlen, buf);
>  }
>  EXPORT_SYMBOL_GPL(mtd_panic_write);
> diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
> index 677768b..791c34d 100644
> --- a/include/linux/mtd/mtd.h
> +++ b/include/linux/mtd/mtd.h
> @@ -330,6 +330,12 @@ struct mtd_info {
>         int (*_get_device) (struct mtd_info *mtd);
>         void (*_put_device) (struct mtd_info *mtd);
>
> +       /*
> +        * flag indicates a panic write, low level drivers can take appropriate
> +        * action if required to ensure writes go through
> +        */
> +       bool oops_panic_write;
> +

Maybe we find a better name for it.
panic_write_triggered?

-- 
Thanks,
//richard