cfg80211: preserve wdev ID across netns changes
When a wdev changes network namespace, its wdev ID will get
reassigned since NETDEV_REGISTER is called again, in the new
network namespace. Avoid that by checking if it was already
assigned before, and document why we do that.
Reported-and-tested-by: Arend Van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/core.c b/net/wireless/core.c
index b1a028d..b0d6761 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1159,7 +1159,15 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
INIT_LIST_HEAD(&wdev->mgmt_registrations);
spin_lock_init(&wdev->mgmt_registrations_lock);
- wdev->identifier = ++rdev->wdev_id;
+ /*
+ * We get here also when the interface changes network namespaces,
+ * as it's registered into the new one, but we don't want it to
+ * change ID in that case. Checking if the ID is already assigned
+ * works, because 0 isn't considered a valid ID and the memory is
+ * 0-initialized.
+ */
+ if (!wdev->identifier)
+ wdev->identifier = ++rdev->wdev_id;
list_add_rcu(&wdev->list, &rdev->wiphy.wdev_list);
rdev->devlist_generation++;
/* can only change netns with wiphy */