netdev: Make netdev_from_name() take a reference to its returned netdev.

This API change is necessary for thread safety, to be added in an upcoming
commit.  Otherwise, the client would not be able to safely use the returned
netdev because it could already have been destroyed.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>

diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 5bbaf632f26d38f4172660a2c57fd7ad50ae215a..c59f590906f2a6d0b5859cd3907d64c793becb78 100644 (file)
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -541,6 +541,7 @@ netdev_linux_cache_cb(const struct rtnetlink_link_change *change,
         struct netdev *base_dev = netdev_from_name(change->ifname);
         if (base_dev && is_netdev_linux_class(netdev_get_class(base_dev))) {
             netdev_linux_update(netdev_linux_cast(base_dev), change);
+            netdev_close(base_dev);
         }
     } else {
         struct shash device_shash;

diff --git a/lib/netdev.c b/lib/netdev.c
index 25615380f4febd7cbc5e35ac6f60e0549d12e91e..30c44a21f4c5aaf27611d3e29dc0d831adf26678 100644 (file)
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -1386,11 +1386,18 @@ netdev_get_class(const struct netdev *netdev)
 
 /* Returns the netdev with 'name' or NULL if there is none.
  *
- * The caller must not free the returned value. */
+ * The caller must free the returned netdev with netdev_close(). */
 struct netdev *
 netdev_from_name(const char *name)
 {
-    return shash_find_data(&netdev_shash, name);
+    struct netdev *netdev;
+
+    netdev = shash_find_data(&netdev_shash, name);
+    if (netdev) {
+        netdev_ref(netdev);
+    }
+
+    return netdev;
 }
 
 /* Fills 'device_list' with devices that match 'netdev_class'.
@@ -1415,8 +1422,10 @@ netdev_get_devices(const struct netdev_class *netdev_class,
 const char *
 netdev_get_type_from_name(const char *name)
 {
-    const struct netdev *dev = netdev_from_name(name);
-    return dev ? netdev_get_type(dev) : NULL;
+    struct netdev *dev = netdev_from_name(name);
+    const char *type = dev ? netdev_get_type(dev) : NULL;
+    netdev_close(dev);
+    return type;
 }
 \f
 void