[PATCH batadv v5 3/6] batman-adv: make hard_iface->mesh_iface immutable

With the hard_iface now being created for a specific mesh_iface, it is
beneficial not to set mesh_iface to NULL when the interface is disabled,
but instead keeping it immutable after the initial setup of the
hard_iface. By also holding the reference to the mesh_iface until the
hard_iface is released, hard_ifaces iterated over under RCU will always
point to a valid mesh_iface.

Co-developed-by: Sven Eckelmann <[email protected]>
Signed-off-by: Nora Schiffer <[email protected]>
---

v5:
- Move immutable mesh_iface change to a new patch

v2-v4 (by Sven Eckelmann):
- Rebase
- Introduce immutable mesh_iface as part of the "remove global hardif
  list" patch


 net/batman-adv/hard-interface.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index ace81348ddef..a0b8b06f9a64 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -63,6 +63,7 @@ void batadv_hardif_release(struct kref *ref)
 	struct batadv_hard_iface *hard_iface;
 
 	hard_iface = container_of(ref, struct batadv_hard_iface, refcount);
+	netdev_put(hard_iface->mesh_iface, &hard_iface->meshif_dev_tracker);
 	netdev_put(hard_iface->net_dev, &hard_iface->dev_tracker);
 
 	kfree_rcu(hard_iface, rcu);
@@ -829,8 +830,6 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 err_upper:
 	netdev_upper_dev_unlink(hard_iface->net_dev, mesh_iface);
 err_dev:
-	hard_iface->mesh_iface = NULL;
-	netdev_put(mesh_iface, &hard_iface->meshif_dev_tracker);
 	batadv_hardif_put(hard_iface);
 	return ret;
 }
@@ -871,7 +870,6 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	/* delete all references to this hard_iface */
 	batadv_purge_orig_ref(bat_priv);
 	batadv_purge_outstanding_packets(bat_priv, hard_iface);
-	netdev_put(hard_iface->mesh_iface, &hard_iface->meshif_dev_tracker);
 
 	batadv_hardif_generation++;
 	netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->mesh_iface);
@@ -881,7 +879,6 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	if (list_empty(&hard_iface->mesh_iface->adj_list.lower))
 		batadv_gw_check_client_stop(bat_priv);
 
-	hard_iface->mesh_iface = NULL;
 	batadv_hardif_put(hard_iface);
 
 out:
-- 
2.54.0