[ovs-discuss] [NIC-20 07/11] datapath: Update sysfs links when network devices are renamed.

[Ben Pfaff]

We create symlinks from /sys/class/net/<bridgename>/brif/<devname> to
/sys/class/net/<devname>/brport, but until now we have never updated the
links when network devices are renamed.  This commit fixes this problem.

(Only the <devname> in /sys/class/net/<bridgename>/brif/<devname> needs to
be updated.  Symlinks within sysfs have stable targets; that is, no matter
how the object that a sysfs symlink points to moves around, the link is
still maintained correctly.)
---
 datapath/datapath.c    |    4 +---
 datapath/datapath.h    |    1 +
 datapath/dp_notify.c   |   23 ++++++++++++++++++++---
 datapath/dp_sysfs_if.c |    5 +++++
 4 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/datapath/datapath.c b/datapath/datapath.c
index f4284ed..bf8043b 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -450,7 +450,7 @@ int dp_del_port(struct net_bridge_port *p)
 
 #ifdef SUPPORT_SYSFS
 	if (p->port_no != ODPP_LOCAL)
-		sysfs_remove_link(&p->dp->ifobj, p->dev->name);
+		dp_sysfs_del_if(p);
 #endif
 	dp_ifinfo_notify(RTM_DELLINK, p);
 
@@ -474,8 +474,6 @@ int dp_del_port(struct net_bridge_port *p)
 
 	if (is_dp_dev(p->dev))
 		dp_dev_destroy(p->dev);
-	if (p->port_no != ODPP_LOCAL)
-		dp_sysfs_del_if(p);
 	dev_put(p->dev);
 	kobject_put(&p->kobj);
 
diff --git a/datapath/datapath.h b/datapath/datapath.h
index 63d92cb..62c79d4 100644
--- a/datapath/datapath.h
+++ b/datapath/datapath.h
@@ -93,6 +93,7 @@ struct net_bridge_port {
 	struct datapath	*dp;
 	struct net_device *dev;
 	struct kobject kobj;
+	char linkname[IFNAMSIZ];
 	struct list_head node;   /* Element in datapath.ports. */
 };
 
diff --git a/datapath/dp_notify.c b/datapath/dp_notify.c
index 5b8cf17..f22d8b3 100644
--- a/datapath/dp_notify.c
+++ b/datapath/dp_notify.c
@@ -17,12 +17,29 @@ static int dp_device_event(struct notifier_block *unused, unsigned long event,
 		void *ptr) 
 {
 	struct net_device *dev = ptr;
-	struct net_bridge_port *p = dev->br_port;
-	if (event == NETDEV_UNREGISTER && p) {
-		struct datapath *dp = p->dp;
+	struct net_bridge_port *p;
+	struct datapath *dp;
+
+	p = dev->br_port;
+	if (!p)
+		return NOTIFY_DONE;
+	dp = p->dp;
+
+	switch (event) {
+	case NETDEV_UNREGISTER:
 		mutex_lock(&dp->mutex);
 		dp_del_port(p);
 		mutex_unlock(&dp->mutex);
+		break;
+
+	case NETDEV_CHANGENAME:
+		if (p->port_no != ODPP_LOCAL) {
+			mutex_lock(&dp->mutex);
+			dp_sysfs_del_if(p);
+			dp_sysfs_add_if(p);
+			mutex_unlock(&dp->mutex);
+		}
+		break;
 	}
 	return NOTIFY_DONE;
 }
diff --git a/datapath/dp_sysfs_if.c b/datapath/dp_sysfs_if.c
index 178afbd..ab928f6 100644
--- a/datapath/dp_sysfs_if.c
+++ b/datapath/dp_sysfs_if.c
@@ -302,6 +302,7 @@ int dp_sysfs_add_if(struct net_bridge_port *p)
 	err = sysfs_create_link(&dp->ifobj, &p->kobj, p->dev->name);
 	if (err)
 		goto err_del;
+	strcpy(p->linkname, p->dev->name);
 
 	kobject_uevent(&p->kobj, KOBJ_ADD);
 
@@ -319,6 +320,10 @@ err_put:
 
 int dp_sysfs_del_if(struct net_bridge_port *p)
 {
+	if (p->linkname[0]) {
+		sysfs_remove_link(&p->dp->ifobj, p->linkname);
+		p->linkname[0] = '\0';
+	}
 	if (p->kobj.dentry) {
 		kobject_uevent(&p->kobj, KOBJ_REMOVE);
 		kobject_del(&p->kobj);
-- 
1.6.3.3