From: Stefan Haberland sth@linux.ibm.com
commit 53a7f655834c7c335bf683f248208d4fbe4b47bc upstream.
In dasd_alias_disconnect_device_from_lcu the device is removed from any list on the LCU. Afterwards the LCU is removed from the lcu list if it does not contain devices any longer.
The lcu->lock protects the lcu from parallel updates. But to cancel all workers and wait for completion the lcu->lock has to be unlocked.
If two devices are removed in parallel and both are removed from the LCU the first device that takes the lcu->lock again will delete the LCU because it is already empty but the second device also tries to free the LCU which leads to a list corruption of the lcu list.
Fix by removing the device right before the lcu is checked without unlocking the lcu->lock in between.
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
--- drivers/s390/block/dasd_alias.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -256,7 +256,6 @@ void dasd_alias_disconnect_device_from_l return; device->discipline->get_uid(device, &uid); spin_lock_irqsave(&lcu->lock, flags); - list_del_init(&device->alias_list); /* make sure that the workers don't use this device */ if (device == lcu->suc_data.device) { spin_unlock_irqrestore(&lcu->lock, flags); @@ -283,6 +282,7 @@ void dasd_alias_disconnect_device_from_l
spin_lock_irqsave(&aliastree.lock, flags); spin_lock(&lcu->lock); + list_del_init(&device->alias_list); if (list_empty(&lcu->grouplist) && list_empty(&lcu->active_devices) && list_empty(&lcu->inactive_devices)) {