9c40d69a3b
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@vger.kernel.org
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.