linux-kernel - Re: [PATCH OLK-5.10 v3 3/4] md/raid10: fix wrong setting of max_corr_read

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Date:   Fri, 19 May 2023 15:06:45 -0700
From:   Song Liu <song@...nel.org>
To:     linan666@...weicloud.com
Cc:     neilb@...e.de, Rob.Becker@...erbed.com, linux-raid@...r.kernel.org,
        linux-kernel@...r.kernel.org, linan122@...wei.com,
        yukuai3@...wei.com, yi.zhang@...wei.com, houtao1@...wei.com,
        yangerkun@...wei.com
Subject: Re: [PATCH OLK-5.10 v3 3/4] md/raid10: fix wrong setting of max_corr_read_errors

On Mon, May 15, 2023 at 6:49 AM <linan666@...weicloud.com> wrote:
>
> From: Li Nan <linan122@...wei.com>
>
> max_corr_read_errors should not be negative number. Change it to
> unsigned int where use it.
>
> Fixes: 1e50915fe0bb ("raid: improve MD/raid10 handling of correctable read errors.")
> Signed-off-by: Li Nan <linan122@...wei.com>
> Reviewed-by: Yu Kuai <yukuai3@...wei.com>
> ---
>  drivers/md/md.c     | 2 +-
>  drivers/md/raid10.c | 5 +++--
>  2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 5bba071ea907..b69ddfb1662a 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4484,7 +4484,7 @@ __ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_stor
>
>  static ssize_t
>  max_corrected_read_errors_show(struct mddev *mddev, char *page) {
> -       return sprintf(page, "%d\n",
> +       return sprintf(page, "%u\n",
>                        atomic_read(&mddev->max_corr_read_errors));
>  }

max_corr_read_errors is atomic_t, so a signed integer. So these
signed => unsigned changes are pretty error prone. Can we just
add check in max_corrected_read_errors_store() so we never store
a negative value?

Thanks,
Song

>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 4fcfcb350d2b..4d615fcc6a50 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -2727,7 +2727,8 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
>         int sect = 0; /* Offset from r10_bio->sector */
>         int sectors = r10_bio->sectors;
>         struct md_rdev *rdev;
> -       int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
> +       unsigned int max_read_errors =
> +                       atomic_read(&mddev->max_corr_read_errors);
>         int d = r10_bio->devs[r10_bio->read_slot].devnum;
>
>         /* still own a reference to this rdev, so it cannot
> @@ -2743,7 +2744,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
>         check_decay_read_errors(mddev, rdev);
>         atomic_inc(&rdev->read_errors);
>         if (atomic_read(&rdev->read_errors) > max_read_errors) {
> -               pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %d:max %d]\n",
> +               pr_notice("md/raid10:%s: %pg: Raid device exceeded read_error threshold [cur %u:max %u]\n",
>                           mdname(mddev), rdev->bdev,
>                           atomic_read(&rdev->read_errors), max_read_errors);
>                 pr_notice("md/raid10:%s: %pg: Failing raid device\n",
> --
> 2.31.1
>