From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:11354 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725871AbgLQQBJ (ORCPT ); Thu, 17 Dec 2020 11:01:09 -0500 From: Stefan Haberland Subject: [PATCH 4/4] s390/dasd: fix list corruption of lcu list Date: Thu, 17 Dec 2020 16:59:07 +0100 Message-Id: <20201217155907.36436-5-sth@linux.ibm.com> In-Reply-To: <20201217155907.36436-1-sth@linux.ibm.com> References: <20201217155907.36436-1-sth@linux.ibm.com> List-ID: To: Jens Axboe Cc: linux-block@vger.kernel.org, Jan Hoeppner , linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Christian Borntraeger 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 Reviewed-by: Jan Hoeppner --- drivers/s390/block/dasd_alias.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c index 60344e13e87b..dc78a523a69f 100644 --- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -256,7 +256,6 @@ void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device) 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_lcu(struct dasd_device *device) 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)) { -- 2.17.1