The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From b41b554c1ee75070a14c02a88496b1f231c7eacc Mon Sep 17 00:00:00 2001
From: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
Date: Thu, 7 Jan 2021 18:24:41 +0100
Subject: [PATCH] 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: 9dc48ccc68b9 ("qeth: serialize sysfs-triggered device configurations")
Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
Reviewed-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index d45e223fc521..cf18d87da41e 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -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;
}
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 37279b1e29f6..4254caf1d9b6 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -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)
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 8d474179ce98..6970597bc885 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -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)
