netdev - [PATCH net 4/4] s390/qeth: conclude all event processing before offlining a card

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Message-Id: <20190204164009.7245-5-jwi@linux.ibm.com>
Date:   Mon,  4 Feb 2019 17:40:09 +0100
From:   Julian Wiedmann <jwi@...ux.ibm.com>
To:     David Miller <davem@...emloft.net>
Cc:     <netdev@...r.kernel.org>, <linux-s390@...r.kernel.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Stefan Raspl <raspl@...ux.ibm.com>,
        Ursula Braun <ubraun@...ux.ibm.com>,
        Julian Wiedmann <jwi@...ux.ibm.com>
Subject: [PATCH net 4/4] s390/qeth: conclude all event processing before offlining a card

Work for Bridgeport events is currently placed on a driver-wide
workqueue. If the card is removed and freed while any such work is still
active, this causes a use-after-free.
So put the events on a per-card queue, where we can control their
lifetime. As we also don't want stale events to last beyond an
offline & online cycle, flush this queue when setting the card offline.

Fixes: b4d72c08b358 ("qeth: bridgeport support - basic control")
Signed-off-by: Julian Wiedmann <jwi@...ux.ibm.com>
---
 drivers/s390/net/qeth_core.h      |  2 +-
 drivers/s390/net/qeth_core_main.c | 10 ++++++++--
 drivers/s390/net/qeth_l2_main.c   |  6 ++++--
 drivers/s390/net/qeth_l3_main.c   |  2 ++
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 1cf45ace0dd0..122059ecad84 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -790,6 +790,7 @@ struct qeth_card {
 	struct qeth_seqno seqno;
 	struct qeth_card_options options;
 
+	struct workqueue_struct *event_wq;
 	wait_queue_head_t wait_q;
 	spinlock_t mclock;
 	unsigned long active_vlans[BITS_TO_LONGS(VLAN_N_VID)];
@@ -963,7 +964,6 @@ extern const struct attribute_group *qeth_osn_attr_groups[];
 extern const struct attribute_group qeth_device_attr_group;
 extern const struct attribute_group qeth_device_blkt_group;
 extern const struct device_type qeth_generic_devtype;
-extern struct workqueue_struct *qeth_wq;
 
 int qeth_card_hw_is_reachable(struct qeth_card *);
 const char *qeth_get_cardname_short(struct qeth_card *);
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 30679bfc8a1b..89f912213e62 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -74,8 +74,7 @@ static void qeth_notify_skbs(struct qeth_qdio_out_q *queue,
 static void qeth_release_skbs(struct qeth_qdio_out_buffer *buf);
 static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *, int);
 
-struct workqueue_struct *qeth_wq;
-EXPORT_SYMBOL_GPL(qeth_wq);
+static struct workqueue_struct *qeth_wq;
 
 int qeth_card_hw_is_reachable(struct qeth_card *card)
 {
@@ -1469,6 +1468,10 @@ static struct qeth_card *qeth_alloc_card(struct ccwgroup_device *gdev)
 	CARD_RDEV(card) = gdev->cdev[0];
 	CARD_WDEV(card) = gdev->cdev[1];
 	CARD_DDEV(card) = gdev->cdev[2];
+
+	card->event_wq = alloc_ordered_workqueue("%s", 0, dev_name(&gdev->dev));
+	if (!card->event_wq)
+		goto out_wq;
 	if (qeth_setup_channel(&card->read, true))
 		goto out_ip;
 	if (qeth_setup_channel(&card->write, true))
@@ -1484,6 +1487,8 @@ static struct qeth_card *qeth_alloc_card(struct ccwgroup_device *gdev)
 out_channel:
 	qeth_clean_channel(&card->read);
 out_ip:
+	destroy_workqueue(card->event_wq);
+out_wq:
 	dev_set_drvdata(&gdev->dev, NULL);
 	kfree(card);
 out:
@@ -5031,6 +5036,7 @@ static void qeth_core_free_card(struct qeth_card *card)
 	qeth_clean_channel(&card->read);
 	qeth_clean_channel(&card->write);
 	qeth_clean_channel(&card->data);
+	destroy_workqueue(card->event_wq);
 	qeth_free_qdio_buffers(card);
 	unregister_service_level(&card->qeth_service_level);
 	dev_set_drvdata(&card->gdev->dev, NULL);
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 9fec0117fc00..a43de2f9bcac 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -369,6 +369,8 @@ static void qeth_l2_stop_card(struct qeth_card *card, int recovery_mode)
 		qeth_clear_cmd_buffers(&card->read);
 		qeth_clear_cmd_buffers(&card->write);
 	}
+
+	flush_workqueue(card->event_wq);
 }
 
 static int qeth_l2_process_inbound_buffer(struct qeth_card *card,
@@ -1436,7 +1438,7 @@ static void qeth_bridge_state_change(struct qeth_card *card,
 	data->card = card;
 	memcpy(&data->qports, qports,
 			sizeof(struct qeth_sbp_state_change) + extrasize);
-	queue_work(qeth_wq, &data->worker);
+	queue_work(card->event_wq, &data->worker);
 }
 
 struct qeth_bridge_host_data {
@@ -1508,7 +1510,7 @@ static void qeth_bridge_host_event(struct qeth_card *card,
 	data->card = card;
 	memcpy(&data->hostevs, hostevs,
 			sizeof(struct qeth_ipacmd_addr_change) + extrasize);
-	queue_work(qeth_wq, &data->worker);
+	queue_work(card->event_wq, &data->worker);
 }
 
 /* SETBRIDGEPORT support; sending commands */
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 5e810561cb12..df34bff4ac31 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1433,6 +1433,8 @@ static void qeth_l3_stop_card(struct qeth_card *card, int recovery_mode)
 		qeth_clear_cmd_buffers(&card->read);
 		qeth_clear_cmd_buffers(&card->write);
 	}
+
+	flush_workqueue(card->event_wq);
 }
 
 /*
-- 
2.16.4