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Message-Id: <20201228124933.460267821@linuxfoundation.org>
Date: Mon, 28 Dec 2020 13:50:02 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Stefan Haberland <sth@...ux.ibm.com>,
Jan Hoeppner <hoeppner@...ux.ibm.com>,
Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 4.19 283/346] s390/dasd: fix list corruption of pavgroup group list
From: Stefan Haberland <sth@...ux.ibm.com>
commit 0ede91f83aa335da1c3ec68eb0f9e228f269f6d8 upstream.
dasd_alias_add_device() moves devices to the active_devices list in case
of a scheduled LCU update regardless if they have previously been in a
pavgroup or not.
Example: device A and B are in the same pavgroup.
Device A has already been in a pavgroup and the private->pavgroup pointer
is set and points to a valid pavgroup. While going through dasd_add_device
it is moved from the pavgroup to the active_devices list.
In parallel device B might be removed from the same pavgroup in
remove_device_from_lcu() which in turn checks if the group is empty
and deletes it accordingly because device A has already been removed from
there.
When now device A enters remove_device_from_lcu() it is tried to remove it
from the pavgroup again because the pavgroup pointer is still set and again
the empty group will be cleaned up which leads to a list corruption.
Fix by setting private->pavgroup to NULL in dasd_add_device.
If the device has been the last device on the pavgroup an empty pavgroup
remains but this will be cleaned up by the scheduled lcu_update which
iterates over all existing pavgroups.
Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Cc: stable@...r.kernel.org
Signed-off-by: Stefan Haberland <sth@...ux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@...ux.ibm.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/s390/block/dasd_alias.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/s390/block/dasd_alias.c
+++ b/drivers/s390/block/dasd_alias.c
@@ -642,6 +642,7 @@ int dasd_alias_add_device(struct dasd_de
}
if (lcu->flags & UPDATE_PENDING) {
list_move(&device->alias_list, &lcu->active_devices);
+ private->pavgroup = NULL;
_schedule_lcu_update(lcu, device);
}
spin_unlock_irqrestore(&lcu->lock, flags);
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