Commit b41b554c authored by Julian Wiedmann's avatar Julian Wiedmann Committed by Jakub Kicinski
Browse files

s390/qeth: fix locking for discipline setup / removal 



Due to insufficient locking, qeth_core_set_online() and
qeth_dev_layer2_store() can run in parallel, both attempting to load &
setup the discipline (and stepping on each other toes along the way).
A similar race can also occur between qeth_core_remove_device() and
qeth_dev_layer2_store().

Access to .discipline is meant to be protected by the discipline_mutex,
so add/expand the locking in qeth_core_remove_device() and
qeth_core_set_online().
Adjust the locking in qeth_l*_remove_device() accordingly, as it's now
handled by the callers in a consistent manner.

Based on an initial patch by Ursula Braun.

Fixes: 9dc48ccc ("qeth: serialize sysfs-triggered device configurations")
Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: default avatarAlexandra Winter <wintera@linux.ibm.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0b9902c1

drivers/s390/net/qeth_core_main.c

+5 −2
Original line number Diff line number Diff line
@@ -6585,6 +6585,7 @@ static int qeth_core_probe_device(struct ccwgroup_device *gdev) 
		break;

	default:

		card->info.layer_enforced = true;

		/* It's so early that we don't need the discipline_mutex yet. */

		rc = qeth_core_load_discipline(card, enforced_disc);

		if (rc)

			goto err_load;
@@ -6617,10 +6618,12 @@ static void qeth_core_remove_device(struct ccwgroup_device *gdev) 


	QETH_CARD_TEXT(card, 2, "removedv");



	mutex_lock(&card->discipline_mutex);

	if (card->discipline) {

		card->discipline->remove(gdev);

		qeth_core_free_discipline(card);

	}

	mutex_unlock(&card->discipline_mutex);



	qeth_free_qdio_queues(card);
@@ -6635,6 +6638,7 @@ static int qeth_core_set_online(struct ccwgroup_device *gdev) 
	int rc = 0;

	enum qeth_discipline_id def_discipline;



	mutex_lock(&card->discipline_mutex);

	if (!card->discipline) {

		def_discipline = IS_IQD(card) ? QETH_DISCIPLINE_LAYER3 :

						QETH_DISCIPLINE_LAYER2;
@@ -6648,11 +6652,10 @@ static int qeth_core_set_online(struct ccwgroup_device *gdev) 
		}

	}



	mutex_lock(&card->discipline_mutex);

	rc = qeth_set_online(card, card->discipline);

	mutex_unlock(&card->discipline_mutex);



err:

	mutex_unlock(&card->discipline_mutex);

	return rc;

}

drivers/s390/net/qeth_l2_main.c

+1 −4
Original line number Diff line number Diff line
@@ -2207,11 +2207,8 @@ static void qeth_l2_remove_device(struct ccwgroup_device *gdev) 
	qeth_set_allowed_threads(card, 0, 1);

	wait_event(card->wait_q, qeth_threads_running(card, 0xffffffff) == 0);



	if (gdev->state == CCWGROUP_ONLINE) {

		mutex_lock(&card->discipline_mutex);

	if (gdev->state == CCWGROUP_ONLINE)

		qeth_set_offline(card, card->discipline, false);

		mutex_unlock(&card->discipline_mutex);

	}



	cancel_work_sync(&card->close_dev_work);

	if (card->dev->reg_state == NETREG_REGISTERED)

drivers/s390/net/qeth_l3_main.c

+1 −4
Original line number Diff line number Diff line
@@ -1970,11 +1970,8 @@ static void qeth_l3_remove_device(struct ccwgroup_device *cgdev) 
	qeth_set_allowed_threads(card, 0, 1);

	wait_event(card->wait_q, qeth_threads_running(card, 0xffffffff) == 0);



	if (cgdev->state == CCWGROUP_ONLINE) {

		mutex_lock(&card->discipline_mutex);

	if (cgdev->state == CCWGROUP_ONLINE)

		qeth_set_offline(card, card->discipline, false);

		mutex_unlock(&card->discipline_mutex);

	}



	cancel_work_sync(&card->close_dev_work);

	if (card->dev->reg_state == NETREG_REGISTERED)