On Wed, Dec 6, 2023 at 12:37 AM Yuya Fujita <fujita.yuya-00@xxxxxxxxxxx> wrote:
>
> Do not unlock all_mddevs_lock in md_seq_show() and keep the lock until
> md_seq_stop().
>
> The list of all_mddevs may be deleted in md_seq_show() because
> all_mddevs_lock is temporarily unlocked.
> The list should not be deleted while iterating over all_mddevs.
> (Just as the list should not be deleted during list_for_each_entry().)
>
> Fixes: cf1b6d4441ff ("md: simplify md_seq_ops")
> Signed-off-by: Yuya Fujita <fujita.yuya-00@xxxxxxxxxxx>
Looks reasonable to me.
Yu Kuai, what do you think about this?
Thanks,
Song
> ---
> drivers/md/md.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index c94373d64f2c..97ef08608848 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8293,7 +8293,6 @@ static int md_seq_show(struct seq_file *seq, void *v)
> if (!mddev_get(mddev))
> return 0;
>
> - spin_unlock(&all_mddevs_lock);
> spin_lock(&mddev->lock);
> if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
> seq_printf(seq, "%s : %sactive", mdname(mddev),
> @@ -8364,7 +8363,6 @@ static int md_seq_show(struct seq_file *seq, void *v)
> seq_printf(seq, "\n");
> }
> spin_unlock(&mddev->lock);
> - spin_lock(&all_mddevs_lock);
> if (atomic_dec_and_test(&mddev->active))
> __mddev_put(mddev);
>
> --
> 2.31.1
>
>
