1 files changed, 39 insertions, 13 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index e350c768d4b5..1770097cfd86 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -188,6 +188,8 @@ static struct napi_struct *napi_by_id(unsigned int napi_id);
 DEFINE_RWLOCK(dev_base_lock);
 EXPORT_SYMBOL(dev_base_lock);
 
+static DEFINE_MUTEX(ifalias_mutex);
+
 /* protects napi_hash addition/deletion and napi_gen_id */
 static DEFINE_SPINLOCK(napi_hash_lock);
 
@@ -1265,29 +1267,53 @@ rollback:
  */
 int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
 {
-	char *new_ifalias;
-
-	ASSERT_RTNL();
+	struct dev_ifalias *new_alias = NULL;
 
 	if (len >= IFALIASZ)
 		return -EINVAL;
 
-	if (!len) {
-		kfree(dev->ifalias);
-		dev->ifalias = NULL;
-		return 0;
+	if (len) {
+		new_alias = kmalloc(sizeof(*new_alias) + len + 1, GFP_KERNEL);
+		if (!new_alias)
+			return -ENOMEM;
+
+		memcpy(new_alias->ifalias, alias, len);
+		new_alias->ifalias[len] = 0;
 	}
 
-	new_ifalias = krealloc(dev->ifalias, len + 1, GFP_KERNEL);
-	if (!new_ifalias)
-		return -ENOMEM;
-	dev->ifalias = new_ifalias;
-	memcpy(dev->ifalias, alias, len);
-	dev->ifalias[len] = 0;
+	mutex_lock(&ifalias_mutex);
+	rcu_swap_protected(dev->ifalias, new_alias,
+			   mutex_is_locked(&ifalias_mutex));
+	mutex_unlock(&ifalias_mutex);
+
+	if (new_alias)
+		kfree_rcu(new_alias, rcuhead);
 
 	return len;
 }
 
+/**
+ *	dev_get_alias - get ifalias of a device
+ *	@dev: device
+ *	@alias: buffer to store name of ifalias
+ *	@len: size of buffer
+ *
+ *	get ifalias for a device.  Caller must make sure dev cannot go
+ *	away,  e.g. rcu read lock or own a reference count to device.
+ */
+int dev_get_alias(const struct net_device *dev, char *name, size_t len)
+{
+	const struct dev_ifalias *alias;
+	int ret = 0;
+
+	rcu_read_lock();
+	alias = rcu_dereference(dev->ifalias);
+	if (alias)
+		ret = snprintf(name, len, "%s", alias->ifalias);
+	rcu_read_unlock();
+
+	return ret;
+}
 
 /**
  *	netdev_features_change - device changes features