Messages in this thread | | | Subject | Re: [PATCH -next 3/7] md: don't rely on 'mddev->pers' to be set in mddev_suspend() | From | Yu Kuai <> | Date | Tue, 22 Aug 2023 10:08:48 +0800 |
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Hi,
在 2023/08/22 8:13, Song Liu 写道: > On Thu, Aug 3, 2023 at 6:30 AM Yu Kuai <yukuai1@huaweicloud.com> wrote: >> >> From: Yu Kuai <yukuai3@huawei.com> >> >> Now that active io is initialized when mddev is allocated, it's safe to >> call mddev_suspend() before 'mddev->pers' is set. >> >> This also prevent null-ptr-def in some cases that caller doesn't >> guarantee 'mddev->pers' to be set. > > This description is a little confusing (to me at least). Please revise it.
Sorry about this, how about this:
'active_io' used to be initialized while the array is running, and 'mddev->pers' is set while the array is running as well. Hence caller must hold 'reconfig_mutex' and guarantee 'mddev->pers' is set before calling mddev_suspend().
Now that 'active_io' is initialized when mddev is allocated, such restriction doesn't exist anymore. In the meantime, follow up patches will refactor mddev_suspend(), hence add checking for 'mddev->pers' to prevent null-ptr-deref.
Thanks, Kuai
> > Other than that, the set looks good to me. > > Thanks, > Song > >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >> --- >> drivers/md/md.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/md/md.c b/drivers/md/md.c >> index 897e94a9e47d..f14f2f0a9484 100644 >> --- a/drivers/md/md.c >> +++ b/drivers/md/md.c >> @@ -448,7 +448,7 @@ void mddev_suspend(struct mddev *mddev) >> set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags); >> percpu_ref_kill(&mddev->active_io); >> >> - if (mddev->pers->prepare_suspend) >> + if (mddev->pers && mddev->pers->prepare_suspend) >> mddev->pers->prepare_suspend(mddev); >> >> wait_event(mddev->sb_wait, percpu_ref_is_zero(&mddev->active_io)); >> -- >> 2.39.2 >> > . >
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