s390/qeth: relax locking for ipato config data

card->ipato is currently protected by the conf_mutex. But most users
also hold the ip_lock - in particular qeth_l3_add_ip().

So slightly expand the sections under ip_lock in a few places (to
effectively cover a few error & no-op cases), and then drop the
conf_mutex where it's no longer needed.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core.h

@@ -814,20 +814,23 @@ struct qeth_card {
 	struct workqueue_struct *event_wq;
 	struct workqueue_struct *cmd_wq;
 	wait_queue_head_t wait_q;
+
+	struct mutex ip_lock;
+	/* protected by ip_lock: */
 	DECLARE_HASHTABLE(ip_htable, 4);
+	struct qeth_ipato ipato;
+
 	DECLARE_HASHTABLE(local_addrs4, 4);
 	DECLARE_HASHTABLE(local_addrs6, 4);
 	spinlock_t local_addrs4_lock;
 	spinlock_t local_addrs6_lock;
-	struct mutex ip_lock;
 	DECLARE_HASHTABLE(rx_mode_addrs, 4);
 	struct work_struct rx_mode_work;
 	struct work_struct kernel_thread_starter;
 	spinlock_t thread_mask_lock;
 	unsigned long thread_start_mask;
 	unsigned long thread_allowed_mask;
 	unsigned long thread_running_mask;
-	struct qeth_ipato ipato;
 	struct list_head cmd_waiter_list;
 	/* QDIO buffer handling */
 	struct qeth_qdio_info qdio;

drivers/s390/net/qeth_l3_main.c

@@ -536,7 +536,6 @@ int qeth_l3_add_ipato_entry(struct qeth_card *card,
 
 	QETH_CARD_TEXT(card, 2, "addipato");
 
-	mutex_lock(&card->conf_mutex);
 	mutex_lock(&card->ip_lock);
 
 	list_for_each_entry(ipatoe, &card->ipato.entries, entry) {
@@ -556,7 +555,6 @@ int qeth_l3_add_ipato_entry(struct qeth_card *card,
 	}
 
 	mutex_unlock(&card->ip_lock);
-	mutex_unlock(&card->conf_mutex);
 
 	return rc;
 }
@@ -570,7 +568,6 @@ int qeth_l3_del_ipato_entry(struct qeth_card *card,
 
 	QETH_CARD_TEXT(card, 2, "delipato");
 
-	mutex_lock(&card->conf_mutex);
 	mutex_lock(&card->ip_lock);
 
 	list_for_each_entry_safe(ipatoe, tmp, &card->ipato.entries, entry) {
@@ -587,7 +584,6 @@ int qeth_l3_del_ipato_entry(struct qeth_card *card,
 	}
 
 	mutex_unlock(&card->ip_lock);
-	mutex_unlock(&card->conf_mutex);
 
 	return rc;
 }

drivers/s390/net/qeth_l3_sys.c

@@ -301,19 +301,21 @@ static ssize_t qeth_l3_dev_ipato_enable_store(struct device *dev,
 		goto out;
 	}
 
+	mutex_lock(&card->ip_lock);
 	if (sysfs_streq(buf, "toggle")) {
 		enable = !card->ipato.enabled;
 	} else if (kstrtobool(buf, &enable)) {
 		rc = -EINVAL;
-		goto out;
+		goto unlock_ip;
 	}
 
 	if (card->ipato.enabled != enable) {
 		card->ipato.enabled = enable;
-		mutex_lock(&card->ip_lock);
 		qeth_l3_update_ipato(card);
-		mutex_unlock(&card->ip_lock);
 	}
+
+unlock_ip:
+	mutex_unlock(&card->ip_lock);
 out:
 	mutex_unlock(&card->conf_mutex);
 	return rc ? rc : count;
@@ -339,7 +341,7 @@ static ssize_t qeth_l3_dev_ipato_invert4_store(struct device *dev,
 	bool invert;
 	int rc = 0;
 
-	mutex_lock(&card->conf_mutex);
+	mutex_lock(&card->ip_lock);
 	if (sysfs_streq(buf, "toggle")) {
 		invert = !card->ipato.invert4;
 	} else if (kstrtobool(buf, &invert)) {
@@ -349,12 +351,11 @@ static ssize_t qeth_l3_dev_ipato_invert4_store(struct device *dev,
 
 	if (card->ipato.invert4 != invert) {
 		card->ipato.invert4 = invert;
-		mutex_lock(&card->ip_lock);
 		qeth_l3_update_ipato(card);
-		mutex_unlock(&card->ip_lock);
 	}
+
 out:
-	mutex_unlock(&card->conf_mutex);
+	mutex_unlock(&card->ip_lock);
 	return rc ? rc : count;
 }
 
@@ -510,7 +511,7 @@ static ssize_t qeth_l3_dev_ipato_invert6_store(struct device *dev,
 	bool invert;
 	int rc = 0;
 
-	mutex_lock(&card->conf_mutex);
+	mutex_lock(&card->ip_lock);
 	if (sysfs_streq(buf, "toggle")) {
 		invert = !card->ipato.invert6;
 	} else if (kstrtobool(buf, &invert)) {
@@ -520,12 +521,11 @@ static ssize_t qeth_l3_dev_ipato_invert6_store(struct device *dev,
 
 	if (card->ipato.invert6 != invert) {
 		card->ipato.invert6 = invert;
-		mutex_lock(&card->ip_lock);
 		qeth_l3_update_ipato(card);
-		mutex_unlock(&card->ip_lock);
 	}
+
 out:
-	mutex_unlock(&card->conf_mutex);
+	mutex_unlock(&card->ip_lock);
 	return rc ? rc : count;
 }