qeth: serialize sysfs-triggered device configurations

This patch serializes device removal and other sysfs-triggered
configurations by moving removal of sysfs-attributes to the beginning
of the remove functions. And it serializes online/offline setting
and discipline-switching (causing reestablishing of the net_device)
by making use of a new discipline mutex.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 32d07c2..5e66333 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -935,6 +935,7 @@
 	enum qeth_card_states recover_flag;
 
 	BUG_ON(!card);
+	mutex_lock(&card->discipline_mutex);
 	mutex_lock(&card->conf_mutex);
 	QETH_DBF_TEXT(SETUP, 2, "setonlin");
 	QETH_DBF_HEX(SETUP, 2, &card, sizeof(void *));
@@ -1012,6 +1013,7 @@
 	kobject_uevent(&gdev->dev.kobj, KOBJ_CHANGE);
 out:
 	mutex_unlock(&card->conf_mutex);
+	mutex_unlock(&card->discipline_mutex);
 	return 0;
 
 out_remove:
@@ -1025,6 +1027,7 @@
 	else
 		card->state = CARD_STATE_DOWN;
 	mutex_unlock(&card->conf_mutex);
+	mutex_unlock(&card->discipline_mutex);
 	return rc;
 }
 
@@ -1040,6 +1043,7 @@
 	int rc = 0, rc2 = 0, rc3 = 0;
 	enum qeth_card_states recover_flag;
 
+	mutex_lock(&card->discipline_mutex);
 	mutex_lock(&card->conf_mutex);
 	QETH_DBF_TEXT(SETUP, 3, "setoffl");
 	QETH_DBF_HEX(SETUP, 3, &card, sizeof(void *));
@@ -1060,6 +1064,7 @@
 	/* let user_space know that device is offline */
 	kobject_uevent(&cgdev->dev.kobj, KOBJ_CHANGE);
 	mutex_unlock(&card->conf_mutex);
+	mutex_unlock(&card->discipline_mutex);
 	return 0;
 }