net: bridge: add support for raw sysfs port options

This patch adds a new alternative store callback for port sysfs options
which takes a raw value (buf) and can use it directly. It is needed for the
backup port sysfs support since we have to pass the device by its name.
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_sysfs_if.c

@@ -25,6 +25,15 @@ struct brport_attribute {
 	struct attribute	attr;
 	ssize_t (*show)(struct net_bridge_port *, char *);
 	int (*store)(struct net_bridge_port *, unsigned long);
+	int (*store_raw)(struct net_bridge_port *, char *);
+};
+
+#define BRPORT_ATTR_RAW(_name, _mode, _show, _store)			\
+const struct brport_attribute brport_attr_##_name = {			\
+	.attr		= {.name = __stringify(_name),			\
+			   .mode = _mode },				\
+	.show		= _show,					\
+	.store_raw	= _store,					\
 };
 
 #define BRPORT_ATTR(_name, _mode, _show, _store)		\
@@ -269,27 +278,46 @@ static ssize_t brport_store(struct kobject *kobj,
 	struct brport_attribute *brport_attr = to_brport_attr(attr);
 	struct net_bridge_port *p = kobj_to_brport(kobj);
 	ssize_t ret = -EINVAL;
-	char *endp;
 	unsigned long val;
+	char *endp;
 
 	if (!ns_capable(dev_net(p->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
-	val = simple_strtoul(buf, &endp, 0);
-	if (endp != buf) {
-		if (!rtnl_trylock())
-			return restart_syscall();
-		if (p->dev && p->br && brport_attr->store) {
-			spin_lock_bh(&p->br->lock);
-			ret = brport_attr->store(p, val);
-			spin_unlock_bh(&p->br->lock);
-			if (!ret) {
-				br_ifinfo_notify(RTM_NEWLINK, NULL, p);
-				ret = count;
-			}
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (!p->dev || !p->br)
+		goto out_unlock;
+
+	if (brport_attr->store_raw) {
+		char *buf_copy;
+
+		buf_copy = kstrndup(buf, count, GFP_KERNEL);
+		if (!buf_copy) {
+			ret = -ENOMEM;
+			goto out_unlock;
 		}
-		rtnl_unlock();
+		spin_lock_bh(&p->br->lock);
+		ret = brport_attr->store_raw(p, buf_copy);
+		spin_unlock_bh(&p->br->lock);
+		kfree(buf_copy);
+	} else if (brport_attr->store) {
+		val = simple_strtoul(buf, &endp, 0);
+		if (endp == buf)
+			goto out_unlock;
+		spin_lock_bh(&p->br->lock);
+		ret = brport_attr->store(p, val);
+		spin_unlock_bh(&p->br->lock);
 	}
+
+	if (!ret) {
+		br_ifinfo_notify(RTM_NEWLINK, NULL, p);
+		ret = count;
+	}
+out_unlock:
+	rtnl_unlock();
+
 	return ret;
 }