Messages in this thread | | | Subject | Re: [PATCH -next 1/2] md: don't quiesce in mddev_suspend() | From | Yu Kuai <> | Date | Wed, 28 Jun 2023 14:29:29 +0800 |
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Hi,
在 2023/06/28 9:29, Yu Kuai 写道: > From: Yu Kuai <yukuai3@huawei.com> > > Some levels doesn't implement "pers->quiesce", for example > raid0_quiesce() is empty, and now that all levels will drop 'active_io' > until io is done, wait for 'active_io' to be 0 is enough to make sure all > normal io is done, and percpu_ref_kill() for 'active_io' will make sure > no new normal io can be dispatched. There is no need to call > "pers->quiesce" anymore from mddev_suspend().
Just found that this patch actually prevent null_ptr_deref in some cases that "pers->quiesce" is NULl for some personalities, and caller of mddev_suspend() doesn't check this. For example, suspend_lo_store() checks "pers->quiesce" is not NULL before calling mddev_suspend(), while suspend_hi_store() doesn't.
Thanks, Kuai > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > --- > drivers/md/md.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/md/md.c b/drivers/md/md.c > index abb616720393..962dacfd98cf 100644 > --- a/drivers/md/md.c > +++ b/drivers/md/md.c > @@ -453,7 +453,6 @@ void mddev_suspend(struct mddev *mddev) > mddev->pers->prepare_suspend(mddev); > > wait_event(mddev->sb_wait, percpu_ref_is_zero(&mddev->active_io)); > - mddev->pers->quiesce(mddev, 1); > clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags); > wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags)); > > @@ -472,7 +471,6 @@ void mddev_resume(struct mddev *mddev) > return; > percpu_ref_resurrect(&mddev->active_io); > wake_up(&mddev->sb_wait); > - mddev->pers->quiesce(mddev, 0); > > set_bit(MD_RECOVERY_NEEDED, &mddev->recovery); > md_wakeup_thread(mddev->thread); >
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