qeth: Make s390dbf card entries persistent

As of now, s390dbf entries for the cards are discarded as soon as the
device is removed. However, this will also bar us of all chances of
getting valuable debug information after a device has been removed.
This patch will keep the s390dbf entries around until the qeth module
is removed.

Signed-off-by: Stefan Raspl <[e-mail]>
Signed-off-by: Frank Blaschka <[e-mail]>
Reviewed-by: Ursula Braun <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/s390/net/qeth_core_main.c

···
 	.groups = qeth_osn_attr_groups,
 };
 
+#define DBF_NAME_LEN	20
+
+struct qeth_dbf_entry {
+	char dbf_name[DBF_NAME_LEN];
+	debug_info_t *dbf_info;
+	struct list_head dbf_list;
+};
+
+static LIST_HEAD(qeth_dbf_list);
+static DEFINE_MUTEX(qeth_dbf_list_mutex);
+
+static debug_info_t *qeth_get_dbf_entry(char *name)
+{
+	struct qeth_dbf_entry *entry;
+	debug_info_t *rc = NULL;
+
+	mutex_lock(&qeth_dbf_list_mutex);
+	list_for_each_entry(entry, &qeth_dbf_list, dbf_list) {
+		if (strcmp(entry->dbf_name, name) == 0) {
+			rc = entry->dbf_info;
+			break;
+		}
+	}
+	mutex_unlock(&qeth_dbf_list_mutex);
+	return rc;
+}
+
+static int qeth_add_dbf_entry(struct qeth_card *card, char *name)
+{
+	struct qeth_dbf_entry *new_entry;
+
+	card->debug = debug_register(name, 2, 1, 8);
+	if (!card->debug) {
+		QETH_DBF_TEXT_(SETUP, 2, "%s", "qcdbf");
+		goto err;
+	}
+	if (debug_register_view(card->debug, &debug_hex_ascii_view))
+		goto err_dbg;
+	new_entry = kzalloc(sizeof(struct qeth_dbf_entry), GFP_KERNEL);
+	if (!new_entry)
+		goto err_dbg;
+	strncpy(new_entry->dbf_name, name, DBF_NAME_LEN);
+	new_entry->dbf_info = card->debug;
+	mutex_lock(&qeth_dbf_list_mutex);
+	list_add(&new_entry->dbf_list, &qeth_dbf_list);
+	mutex_unlock(&qeth_dbf_list_mutex);
+
+	return 0;
+
+err_dbg:
+	debug_unregister(card->debug);
+err:
+	return -ENOMEM;
+}
+
+static void qeth_clear_dbf_list(void)
+{
+	struct qeth_dbf_entry *entry, *tmp;
+
+	mutex_lock(&qeth_dbf_list_mutex);
+	list_for_each_entry_safe(entry, tmp, &qeth_dbf_list, dbf_list) {
+		list_del(&entry->dbf_list);
+		debug_unregister(entry->dbf_info);
+		kfree(entry);
+	}
+	mutex_unlock(&qeth_dbf_list_mutex);
+}
+
 static int qeth_core_probe_device(struct ccwgroup_device *gdev)
 {
 	struct qeth_card *card;
 	struct device *dev;
 	int rc;
 	unsigned long flags;
-	char dbf_name[20];
+	char dbf_name[DBF_NAME_LEN];
 
 	QETH_DBF_TEXT(SETUP, 2, "probedev");
 
···
 
 	snprintf(dbf_name, sizeof(dbf_name), "qeth_card_%s",
 		dev_name(&gdev->dev));
-	card->debug = debug_register(dbf_name, 2, 1, 8);
+	card->debug = qeth_get_dbf_entry(dbf_name);
 	if (!card->debug) {
-		QETH_DBF_TEXT_(SETUP, 2, "%s", "qcdbf");
-		rc = -ENOMEM;
-		goto err_card;
+		rc = qeth_add_dbf_entry(card, dbf_name);
+		if (rc)
+			goto err_card;
 	}
-	debug_register_view(card->debug, &debug_hex_ascii_view);
 
 	card->read.ccwdev  = gdev->cdev[0];
 	card->write.ccwdev = gdev->cdev[1];
···
 	rc = qeth_determine_card_type(card);
 	if (rc) {
 		QETH_DBF_TEXT_(SETUP, 2, "3err%d", rc);
-		goto err_dbf;
+		goto err_card;
 	}
 	rc = qeth_setup_card(card);
 	if (rc) {
 		QETH_DBF_TEXT_(SETUP, 2, "2err%d", rc);
-		goto err_dbf;
+		goto err_card;
 	}
 
 	if (card->info.type == QETH_CARD_TYPE_OSN)
···
 	case QETH_CARD_TYPE_OSM:
 		rc = qeth_core_load_discipline(card, QETH_DISCIPLINE_LAYER2);
 		if (rc)
-			goto err_dbf;
+			goto err_card;
 		rc = card->discipline->setup(card->gdev);
 		if (rc)
 			goto err_disc;
···
 
 err_disc:
 	qeth_core_free_discipline(card);
-err_dbf:
-	debug_unregister(card->debug);
 err_card:
 	qeth_core_free_card(card);
 err_dev:
···
 		qeth_core_free_discipline(card);
 	}
 
-	debug_unregister(card->debug);
 	write_lock_irqsave(&qeth_core_card_list.rwlock, flags);
 	list_del(&card->list);
 	write_unlock_irqrestore(&qeth_core_card_list.rwlock, flags);
···
 
 	pr_info("loading core functions\n");
 	INIT_LIST_HEAD(&qeth_core_card_list.list);
+	INIT_LIST_HEAD(&qeth_dbf_list);
 	rwlock_init(&qeth_core_card_list.rwlock);
 	mutex_init(&qeth_mod_mutex);
 
···
 
 static void __exit qeth_core_exit(void)
 {
+	qeth_clear_dbf_list();
 	destroy_workqueue(qeth_wq);
 	ccwgroup_driver_unregister(&qeth_core_ccwgroup_driver);
 	ccw_driver_unregister(&qeth_ccw_driver);