[PATCH AUTOSEL 6.5 08/37] md: don't rely on 'mddev->pers' to be set in mddev_suspend()

From: Sasha Levin
Date: Tue Nov 07 2023 - 07:36:18 EST


From: Yu Kuai <yukuai3@xxxxxxxxxx>

[ Upstream commit b721e7885eb242aa2459ee66bb42ceef1bcf0f0c ]

'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.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230825030956.1527023-4-yukuai1@xxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 78d51dddf3a00..34b7196d9634c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -449,7 +449,7 @@ 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));
--
2.42.0