Commit c8183f54 authored by Julian Wiedmann's avatar Julian Wiedmann Committed by David S. Miller
Browse files

s390/qeth: fix potential deadlock on workqueue flush 



The L2 bridgeport code uses the coarse 'conf_mutex' for guarding access
to its configuration state.
This can result in a deadlock when qeth_l2_stop_card() - called under the
conf_mutex - blocks on flush_workqueue() to wait for the completion of
pending bridgeport workers. Such workers would also need to aquire
the conf_mutex, stalling indefinitely.

Introduce a lock that specifically guards the bridgeport configuration,
so that the workers no longer need the conf_mutex.
Wrapping qeth_l2_promisc_to_bridge() in this fine-grained lock then also
fixes a theoretical race against a concurrent qeth_bridge_port_role_store()
operation.

Fixes: c0a2e4d1 ("s390/qeth: conclude all event processing before offlining a card")
Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: default avatarAlexandra Winter <wintera@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 004b3942

drivers/s390/net/qeth_core.h

+1 −0
Original line number Diff line number Diff line
@@ -839,6 +839,7 @@ struct qeth_card { 
	struct service_level qeth_service_level;

	struct qdio_ssqd_desc ssqd;

	debug_info_t *debug;

	struct mutex sbp_lock;

	struct mutex conf_mutex;

	struct mutex discipline_mutex;

	struct napi_struct napi;

drivers/s390/net/qeth_l2_main.c

+14 −7
Original line number Diff line number Diff line
@@ -467,10 +467,14 @@ static void qeth_l2_set_promisc_mode(struct qeth_card *card) 
	if (card->info.promisc_mode == enable)

		return;



	if (qeth_adp_supported(card, IPA_SETADP_SET_PROMISC_MODE))

	if (qeth_adp_supported(card, IPA_SETADP_SET_PROMISC_MODE)) {

		qeth_setadp_promisc_mode(card, enable);

	else if (card->options.sbp.reflect_promisc)

	} else {

		mutex_lock(&card->sbp_lock);

		if (card->options.sbp.reflect_promisc)

			qeth_l2_promisc_to_bridge(card, enable);

		mutex_unlock(&card->sbp_lock);

	}

}



/* New MAC address is added to the hash table and marked to be written on card
@@ -631,6 +635,7 @@ static int qeth_l2_probe_device(struct ccwgroup_device *gdev) 
	int rc;



	qeth_l2_vnicc_set_defaults(card);

	mutex_init(&card->sbp_lock);



	if (gdev->dev.type == &qeth_generic_devtype) {

		rc = qeth_l2_create_device_attributes(&gdev->dev);
@@ -804,10 +809,12 @@ static int qeth_l2_set_online(struct ccwgroup_device *gdev) 
	} else

		card->info.hwtrap = 0;



	mutex_lock(&card->sbp_lock);

	qeth_bridgeport_query_support(card);

	if (card->options.sbp.supported_funcs)

		dev_info(&card->gdev->dev,

		"The device represents a Bridge Capable Port\n");

	mutex_unlock(&card->sbp_lock);



	qeth_l2_register_dev_addr(card);
@@ -1162,9 +1169,9 @@ static void qeth_bridge_state_change_worker(struct work_struct *work) 


	/* Role should not change by itself, but if it did, */

	/* information from the hardware is authoritative.  */

	mutex_lock(&data->card->conf_mutex);

	mutex_lock(&data->card->sbp_lock);

	data->card->options.sbp.role = entry->role;

	mutex_unlock(&data->card->conf_mutex);

	mutex_unlock(&data->card->sbp_lock);



	snprintf(env_locrem, sizeof(env_locrem), "BRIDGEPORT=statechange");

	snprintf(env_role, sizeof(env_role), "ROLE=%s",
@@ -1230,9 +1237,9 @@ static void qeth_bridge_host_event_worker(struct work_struct *work) 
			: (data->hostevs.lost_event_mask == 0x02)

			? "Bridge port state change"

			: "Unknown reason");

		mutex_lock(&data->card->conf_mutex);

		mutex_lock(&data->card->sbp_lock);

		data->card->options.sbp.hostnotification = 0;

		mutex_unlock(&data->card->conf_mutex);

		mutex_unlock(&data->card->sbp_lock);

		qeth_bridge_emit_host_event(data->card, anev_abort,

			0, NULL, NULL);

	} else

drivers/s390/net/qeth_l2_sys.c

+13 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev, 
	if (qeth_l2_vnicc_is_in_use(card))

		return sprintf(buf, "n/a (VNIC characteristics)\n");



	mutex_lock(&card->sbp_lock);

	if (qeth_card_hw_is_reachable(card) &&

					card->options.sbp.supported_funcs)

		rc = qeth_bridgeport_query_ports(card,
@@ -57,6 +58,7 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev, 
		else

			rc = sprintf(buf, "%s\n", word);

	}

	mutex_unlock(&card->sbp_lock);



	return rc;

}
@@ -91,6 +93,7 @@ static ssize_t qeth_bridge_port_role_store(struct device *dev, 
		return -EINVAL;



	mutex_lock(&card->conf_mutex);

	mutex_lock(&card->sbp_lock);



	if (qeth_l2_vnicc_is_in_use(card))

		rc = -EBUSY;
@@ -104,6 +107,7 @@ static ssize_t qeth_bridge_port_role_store(struct device *dev, 
	} else

		card->options.sbp.role = role;



	mutex_unlock(&card->sbp_lock);

	mutex_unlock(&card->conf_mutex);



	return rc ? rc : count;
@@ -158,6 +162,7 @@ static ssize_t qeth_bridgeport_hostnotification_store(struct device *dev, 
		return rc;



	mutex_lock(&card->conf_mutex);

	mutex_lock(&card->sbp_lock);



	if (qeth_l2_vnicc_is_in_use(card))

		rc = -EBUSY;
@@ -168,6 +173,7 @@ static ssize_t qeth_bridgeport_hostnotification_store(struct device *dev, 
	} else

		card->options.sbp.hostnotification = enable;



	mutex_unlock(&card->sbp_lock);

	mutex_unlock(&card->conf_mutex);



	return rc ? rc : count;
@@ -223,6 +229,7 @@ static ssize_t qeth_bridgeport_reflect_store(struct device *dev, 
		return -EINVAL;



	mutex_lock(&card->conf_mutex);

	mutex_lock(&card->sbp_lock);



	if (qeth_l2_vnicc_is_in_use(card))

		rc = -EBUSY;
@@ -234,6 +241,7 @@ static ssize_t qeth_bridgeport_reflect_store(struct device *dev, 
		rc = 0;

	}



	mutex_unlock(&card->sbp_lock);

	mutex_unlock(&card->conf_mutex);



	return rc ? rc : count;
@@ -269,6 +277,8 @@ void qeth_l2_setup_bridgeport_attrs(struct qeth_card *card) 
		return;

	if (!card->options.sbp.supported_funcs)

		return;



	mutex_lock(&card->sbp_lock);

	if (card->options.sbp.role != QETH_SBP_ROLE_NONE) {

		/* Conditional to avoid spurious error messages */

		qeth_bridgeport_setrole(card, card->options.sbp.role);
@@ -280,9 +290,11 @@ void qeth_l2_setup_bridgeport_attrs(struct qeth_card *card) 
		rc = qeth_bridgeport_an_set(card, 1);

		if (rc)

			card->options.sbp.hostnotification = 0;

	} else

	} else {

		qeth_bridgeport_an_set(card, 0);

	}

	mutex_unlock(&card->sbp_lock);

}



/* VNIC CHARS support */

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