[PATCH batadv v5 0/6] batman-adv: drop global hard interface list

[PATCH batadv v5 0/6] batman-adv: drop global hard interface list

[Nora Schiffer]

Cover letter from Sven's v4:

The global hard interface list was used in the past to provide and sysfs
(debugfs, procfs) based configuration interface. This requirement is gone
after it was switched to generic netlink and NETLINK_ROUTE. And after the
wifi-flags cache was introduced, it is also no longer used to get
non-batman-adv attached interface information (for ap_isolation and
re-broadcast configuration).

But this odd net_devices list (batadv_hardif_list) stayed and caused some
headaches:

* memory requirement increased (useless) for each network interface of the
  system
* massive increase of various ethernet operations due to the O(n) nature of
  this global list
* the code had to handle switch of a batadv_hard_iface from one mesh_iface
  to either NULL or a different mesh_iface

Just get rid of it now and start to simplify the code around it.

---

@Sven: Feel free to update the author of "make hard_iface->mesh_iface immutable"
to yourself, as I only pulled your change out into a separate patch.

---

Changes in v5:
- Rebase
- Improve commit description of patch 1
- Further simplify refcounting in enable/disable (holding only 1 ref instead of 3)
- Move immutable hard_iface->mesh_iface change to a separate change
- One new patch with a minor code cleanup
- Sven's follow-up cleanups are not included in this series


Revisions by Sven Eckelmann:

Changes in v4:
- rebase
- don't double-netdev_put in batadv_hardif_enable_interface() error path
  (just let batadv_hardif_put()/batadv_hardif_release() deal with it)
- add patches which cleanup the code after batadv_hard_iface->mesh_iface
  became immutable
- Link to v3: https://patch.msgid.link/20260604-drop-hardif-list-v3-0-e0dfa8c7d602@narfation.org

Changes in v3:
- fix return kernel-doc for batadv_hardif_enable_interface
- drop merged first patch
- really switch to RFC
- in merged batadv_hardif_enable_interface (as intermediate step), only add
  the hard_iface to the batadv_hardif_list when hard_iface is really
  initialized
  + this list is dropped anyway with the patch "remove global hardif list"
- stop setting "mesh_iface" to NULL on error. it is now only important that
  the hard_iface gets unlinked from the mesh_iface
- first drop the batadv_hardif_list before removing the "safety" state
  BATADV_IF_NOT_IN_USE
- Link to v2: https://patch.msgid.link/20260603-drop-hardif-list-v2-0-5f79821ca333@narfation.org

Changes in v2:
- rebased
- submit as RFC to get the discussion started again
- drop already merged "batman-adv: store hard_iface as iflink private data"
- switch from kzalloc to kzalloc_obj
- update author's mail and name
- fix reference counting for batman_adv_ptype
- Link to v1: https://patch.msgid.link/0b26554afea5203820faef1dfb498af7533a9b5d.1747687504.git.mschiffer@universe-factory.net


Nora Schiffer (6):
  batman-adv: create hardif only for netdevs that are part of a mesh
  batman-adv: remove global hardif list
  batman-adv: make hard_iface->mesh_iface immutable
  batman-adv: remove BATADV_IF_NOT_IN_USE hardif state
  batman-adv: move hardif generation counter into batadv_priv
  batman-adv: drop unneeded goto and initialization from
    batadv_hardif_disable_interface()

 net/batman-adv/bat_iv_ogm.c     |   3 +-
 net/batman-adv/bat_v_elp.c      |   3 +-
 net/batman-adv/hard-interface.c | 157 +++++++++++---------------------
 net/batman-adv/hard-interface.h |  10 +-
 net/batman-adv/main.c           |   6 --
 net/batman-adv/main.h           |   3 -
 net/batman-adv/mesh-interface.c |  13 +--
 net/batman-adv/netlink.c        |   4 +-
 net/batman-adv/originator.c     |   4 -
 net/batman-adv/types.h          |   6 +-
 10 files changed, 62 insertions(+), 147 deletions(-)

-- 
2.54.0

[PATCH batadv v5 1/6] batman-adv: create hardif only for netdevs that are part of a mesh

[Nora Schiffer]

batman-adv is using netdev notifiers to create a hard_iface struct for
every Ethernet-like netdev in the system. These hardifs are tracked in a
global linked list, which results in a few performance issues:

Lookups in this list are O(n) in the total number of netdevs. As a
hardif is looked up when a netdev is removed, this also takes O(n) in
the number of netdevs, and removing n netdevs may take O(n^2). This
slowdown will always happen when the batman-adv module is loaded, no
mesh needs to be active.

With the hardif being referenced as iflink private data, the global list
is only needed for hardifs that are *not* part of a mesh (that is, the
hardif is unused). To prepare for removing the global list, only create
a hardif struct when an interface is added to a mesh and destroy it on
removal.

As adding/removing and enabling/disabling a hardif become one and the
same, batadv_hardif_add_interface() is merged into
batadv_hardif_enable_interface(), and batadv_hardif_remove_interface()
can be dropped altogether.

Co-developed-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

v5:
- further simplify refcounting (only holding a single ref at the end
  of enable_interface(), thus only needing batadv_hardif_put() once in
  disable_interface())
- improve commit message

v2-v4 (by Sven Eckelmann):
- rebase only current main
- fix refcounting issues


 net/batman-adv/hard-interface.c | 120 +++++++++++---------------------
 net/batman-adv/hard-interface.h |   2 +-
 net/batman-adv/mesh-interface.c |  13 +---
 3 files changed, 44 insertions(+), 91 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 03d01c20a954..9c9a892d22c6 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -723,33 +723,58 @@ batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
 }
 
 /**
- * batadv_hardif_enable_interface() - Enslave hard interface to mesh interface
- * @hard_iface: hard interface to add to mesh interface
+ * batadv_hardif_enable_interface() - Enslave interface to mesh interface
+ * @net_dev: netdev struct of the interface to add to mesh interface
  * @mesh_iface: netdev struct of the mesh interface
  *
  * Return: 0 on success or negative error number in case of failure
  */
-int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
+int batadv_hardif_enable_interface(struct net_device *net_dev,
 				   struct net_device *mesh_iface)
 {
 	struct batadv_priv *bat_priv;
 	__be16 ethertype = htons(ETH_P_BATMAN);
 	int max_header_len = batadv_max_header_len();
+	struct batadv_hard_iface *hard_iface;
 	unsigned int required_mtu;
 	unsigned int hardif_mtu;
 	bool fragmentation;
 	int ret;
 
-	hardif_mtu = READ_ONCE(hard_iface->net_dev->mtu);
+	ASSERT_RTNL();
+
+	if (!batadv_is_valid_iface(net_dev))
+		return -EINVAL;
+
+	hardif_mtu = READ_ONCE(net_dev->mtu);
 	required_mtu = READ_ONCE(mesh_iface->mtu) + max_header_len;
 
 	if (hardif_mtu < ETH_MIN_MTU + max_header_len)
 		return -EINVAL;
 
-	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
-		goto out;
+	hard_iface = kzalloc_obj(*hard_iface, GFP_ATOMIC);
+	if (!hard_iface)
+		return -ENOMEM;
+
+	netdev_hold(net_dev, &hard_iface->dev_tracker, GFP_ATOMIC);
+	hard_iface->net_dev = net_dev;
+
+	hard_iface->if_status = BATADV_IF_INACTIVE;
+
+	INIT_LIST_HEAD(&hard_iface->list);
+	INIT_HLIST_HEAD(&hard_iface->neigh_list);
 
-	kref_get(&hard_iface->refcount);
+	mutex_init(&hard_iface->bat_iv.ogm_buff_mutex);
+	spin_lock_init(&hard_iface->neigh_list_lock);
+	kref_init(&hard_iface->refcount);
+
+	hard_iface->num_bcasts = BATADV_NUM_BCASTS_DEFAULT;
+	if (batadv_is_wifi_hardif(hard_iface))
+		hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
+
+	WRITE_ONCE(hard_iface->hop_penalty, 0);
+
+	batadv_v_hardif_init(hard_iface);
 
 	netdev_hold(mesh_iface, &hard_iface->meshif_dev_tracker, GFP_ATOMIC);
 	hard_iface->mesh_iface = mesh_iface;
@@ -764,9 +789,6 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 	if (ret < 0)
 		goto err_upper;
 
-	hard_iface->if_status = BATADV_IF_INACTIVE;
-
-	kref_get(&hard_iface->refcount);
 	hard_iface->batman_adv_ptype.type = ethertype;
 	hard_iface->batman_adv_ptype.func = batadv_batman_skb_recv;
 	hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
@@ -802,7 +824,9 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 	if (bat_priv->algo_ops->iface.enabled)
 		bat_priv->algo_ops->iface.enabled(hard_iface);
 
-out:
+	list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
+	batadv_hardif_generation++;
+
 	return 0;
 
 err_upper:
@@ -823,15 +847,19 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->mesh_iface);
 	struct batadv_hard_iface *primary_if = NULL;
 
+	ASSERT_RTNL();
+
 	batadv_hardif_deactivate_interface(hard_iface);
 
 	if (hard_iface->if_status != BATADV_IF_INACTIVE)
 		goto out;
 
+	list_del_rcu(&hard_iface->list);
+	batadv_hardif_generation++;
+
 	batadv_info(hard_iface->mesh_iface, "Removing interface: %s\n",
 		    hard_iface->net_dev->name);
 	dev_remove_pack(&hard_iface->batman_adv_ptype);
-	batadv_hardif_put(hard_iface);
 
 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (hard_iface == primary_if) {
@@ -844,7 +872,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	}
 
 	bat_priv->algo_ops->iface.disable(hard_iface);
-	hard_iface->if_status = BATADV_IF_NOT_IN_USE;
+	hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
 
 	/* delete all references to this hard_iface */
 	batadv_purge_orig_ref(bat_priv);
@@ -865,63 +893,6 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	batadv_hardif_put(primary_if);
 }
 
-static struct batadv_hard_iface *
-batadv_hardif_add_interface(struct net_device *net_dev)
-{
-	struct batadv_hard_iface *hard_iface;
-
-	ASSERT_RTNL();
-
-	if (!batadv_is_valid_iface(net_dev))
-		return NULL;
-
-	hard_iface = kzalloc_obj(*hard_iface, GFP_ATOMIC);
-	if (!hard_iface)
-		return NULL;
-
-	netdev_hold(net_dev, &hard_iface->dev_tracker, GFP_ATOMIC);
-	hard_iface->net_dev = net_dev;
-
-	hard_iface->mesh_iface = NULL;
-	hard_iface->if_status = BATADV_IF_NOT_IN_USE;
-
-	INIT_LIST_HEAD(&hard_iface->list);
-	INIT_HLIST_HEAD(&hard_iface->neigh_list);
-
-	mutex_init(&hard_iface->bat_iv.ogm_buff_mutex);
-	spin_lock_init(&hard_iface->neigh_list_lock);
-	kref_init(&hard_iface->refcount);
-
-	hard_iface->num_bcasts = BATADV_NUM_BCASTS_DEFAULT;
-	if (batadv_is_wifi_hardif(hard_iface))
-		hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
-
-	WRITE_ONCE(hard_iface->hop_penalty, 0);
-
-	batadv_v_hardif_init(hard_iface);
-
-	kref_get(&hard_iface->refcount);
-	list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
-	batadv_hardif_generation++;
-
-	return hard_iface;
-}
-
-static void batadv_hardif_remove_interface(struct batadv_hard_iface *hard_iface)
-{
-	ASSERT_RTNL();
-
-	/* first deactivate interface */
-	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
-		batadv_hardif_disable_interface(hard_iface);
-
-	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
-		return;
-
-	hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
-	batadv_hardif_put(hard_iface);
-}
-
 /**
  * batadv_hard_if_event_meshif() - Handle events for mesh interfaces
  * @event: NETDEV_* event to handle
@@ -1082,10 +1053,6 @@ static int batadv_hard_if_event(struct notifier_block *this,
 	batadv_wifi_net_device_event(event, net_dev);
 
 	hard_iface = batadv_hardif_get_by_netdev(net_dev);
-	if (!hard_iface && (event == NETDEV_REGISTER ||
-			    event == NETDEV_POST_TYPE_CHANGE))
-		hard_iface = batadv_hardif_add_interface(net_dev);
-
 	if (!hard_iface)
 		goto out;
 
@@ -1099,10 +1066,7 @@ static int batadv_hard_if_event(struct notifier_block *this,
 		break;
 	case NETDEV_UNREGISTER:
 	case NETDEV_PRE_TYPE_CHANGE:
-		list_del_rcu(&hard_iface->list);
-		batadv_hardif_generation++;
-
-		batadv_hardif_remove_interface(hard_iface);
+		batadv_hardif_disable_interface(hard_iface);
 		break;
 	case NETDEV_CHANGEMTU:
 		if (hard_iface->mesh_iface)
diff --git a/net/batman-adv/hard-interface.h b/net/batman-adv/hard-interface.h
index af31696c3978..6d72dbdd5c20 100644
--- a/net/batman-adv/hard-interface.h
+++ b/net/batman-adv/hard-interface.h
@@ -75,7 +75,7 @@ u32 batadv_hardif_get_wifi_flags(struct batadv_hard_iface *hard_iface);
 bool batadv_is_wifi_hardif(struct batadv_hard_iface *hard_iface);
 struct batadv_hard_iface*
 batadv_hardif_get_by_netdev(const struct net_device *net_dev);
-int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
+int batadv_hardif_enable_interface(struct net_device *net_dev,
 				   struct net_device *mesh_iface);
 void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface);
 int batadv_hardif_min_mtu(struct net_device *mesh_iface);
diff --git a/net/batman-adv/mesh-interface.c b/net/batman-adv/mesh-interface.c
index e5a55d242052..0411a0ba675f 100644
--- a/net/batman-adv/mesh-interface.c
+++ b/net/batman-adv/mesh-interface.c
@@ -836,18 +836,7 @@ static int batadv_meshif_slave_add(struct net_device *dev,
 				   struct net_device *slave_dev,
 				   struct netlink_ext_ack *extack)
 {
-	struct batadv_hard_iface *hard_iface;
-	int ret = -EINVAL;
-
-	hard_iface = batadv_hardif_get_by_netdev(slave_dev);
-	if (!hard_iface || hard_iface->mesh_iface)
-		goto out;
-
-	ret = batadv_hardif_enable_interface(hard_iface, dev);
-
-out:
-	batadv_hardif_put(hard_iface);
-	return ret;
+	return batadv_hardif_enable_interface(slave_dev, dev);
 }
 
 /**
-- 
2.54.0

[PATCH batadv v5 2/6] batman-adv: remove global hardif list

[Nora Schiffer]

With interfaces being kept track of as iflink private data, there is no
need for the global list anymore. batadv_hardif_get_by_netdev() can now
use netdev_master_upper_dev_get()+netdev_lower_dev_get_private() to find
the hardif corresponding to a netdev.

Co-developed-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

v5:
- Move immutable hard_iface->mesh_iface change to a separate patch

  If hard_iface->mesh_iface becoming NULL during disable wasn't an issue
  before this patch, it shouldn't become one with it. The change is
  still useful for follow-up cleanup, but it seems more appropriate to
  move it to its own patch.

v2-v4 (by Sven Eckelmann):
- Rebase onto current main
- Add missing RTNL around batadv_hardif_get_by_netdev() in
  batadv_netlink_get_hardif_from_ifindex
- Keep hard_iface->mesh_iface immutable and valid as long as hardif
  exists


 net/batman-adv/hard-interface.c | 29 ++++++++++++-----------------
 net/batman-adv/hard-interface.h |  2 +-
 net/batman-adv/main.c           |  5 -----
 net/batman-adv/main.h           |  1 -
 net/batman-adv/netlink.c        |  2 ++
 net/batman-adv/types.h          |  3 ---
 6 files changed, 15 insertions(+), 27 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 9c9a892d22c6..ace81348ddef 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -75,21 +75,21 @@ void batadv_hardif_release(struct kref *ref)
  * Return: batadv_hard_iface of net_dev (with increased refcnt), NULL on errors
  */
 struct batadv_hard_iface *
-batadv_hardif_get_by_netdev(const struct net_device *net_dev)
+batadv_hardif_get_by_netdev(struct net_device *net_dev)
 {
 	struct batadv_hard_iface *hard_iface;
+	struct net_device *mesh_iface;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
-		if (hard_iface->net_dev == net_dev &&
-		    kref_get_unless_zero(&hard_iface->refcount))
-			goto out;
-	}
+	ASSERT_RTNL();
 
-	hard_iface = NULL;
+	mesh_iface = netdev_master_upper_dev_get(net_dev);
+	if (!mesh_iface || !batadv_meshif_is_valid(mesh_iface))
+		return NULL;
+
+	hard_iface = netdev_lower_dev_get_private(mesh_iface, net_dev);
+	if (!kref_get_unless_zero(&hard_iface->refcount))
+		return NULL;
 
-out:
-	rcu_read_unlock();
 	return hard_iface;
 }
 
@@ -761,7 +761,6 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 
 	hard_iface->if_status = BATADV_IF_INACTIVE;
 
-	INIT_LIST_HEAD(&hard_iface->list);
 	INIT_HLIST_HEAD(&hard_iface->neigh_list);
 
 	mutex_init(&hard_iface->bat_iv.ogm_buff_mutex);
@@ -780,6 +779,7 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 	hard_iface->mesh_iface = mesh_iface;
 	bat_priv = netdev_priv(hard_iface->mesh_iface);
 
+	batadv_hardif_generation++;
 	ret = netdev_master_upper_dev_link(hard_iface->net_dev,
 					   mesh_iface, hard_iface, NULL, NULL);
 	if (ret)
@@ -824,9 +824,6 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 	if (bat_priv->algo_ops->iface.enabled)
 		bat_priv->algo_ops->iface.enabled(hard_iface);
 
-	list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
-	batadv_hardif_generation++;
-
 	return 0;
 
 err_upper:
@@ -854,9 +851,6 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	if (hard_iface->if_status != BATADV_IF_INACTIVE)
 		goto out;
 
-	list_del_rcu(&hard_iface->list);
-	batadv_hardif_generation++;
-
 	batadv_info(hard_iface->mesh_iface, "Removing interface: %s\n",
 		    hard_iface->net_dev->name);
 	dev_remove_pack(&hard_iface->batman_adv_ptype);
@@ -879,6 +873,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	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);
 	batadv_hardif_recalc_extra_skbroom(hard_iface->mesh_iface);
 
diff --git a/net/batman-adv/hard-interface.h b/net/batman-adv/hard-interface.h
index 6d72dbdd5c20..aa9275dec097 100644
--- a/net/batman-adv/hard-interface.h
+++ b/net/batman-adv/hard-interface.h
@@ -74,7 +74,7 @@ u32 batadv_netdev_get_wifi_flags(struct net_device *net_dev);
 u32 batadv_hardif_get_wifi_flags(struct batadv_hard_iface *hard_iface);
 bool batadv_is_wifi_hardif(struct batadv_hard_iface *hard_iface);
 struct batadv_hard_iface*
-batadv_hardif_get_by_netdev(const struct net_device *net_dev);
+batadv_hardif_get_by_netdev(struct net_device *net_dev);
 int batadv_hardif_enable_interface(struct net_device *net_dev,
 				   struct net_device *mesh_iface);
 void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface);
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 3c4572284b53..1d82f3a841a1 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -59,10 +59,6 @@
 #include "tp_meter.h"
 #include "translation-table.h"
 
-/* List manipulations on hardif_list have to be rtnl_lock()'ed,
- * list traversals just rcu-locked
- */
-struct list_head batadv_hardif_list;
 unsigned int batadv_hardif_generation;
 static int (*batadv_rx_handler[256])(struct sk_buff *skb,
 				     struct batadv_hard_iface *recv_if);
@@ -95,7 +91,6 @@ static int __init batadv_init(void)
 	if (ret < 0)
 		return ret;
 
-	INIT_LIST_HEAD(&batadv_hardif_list);
 	batadv_algo_init();
 
 	batadv_recv_handler_init();
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index f68fc8b7239c..e34145047a34 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -226,7 +226,6 @@ static inline int batadv_print_vid(unsigned short vid)
 		return -1;
 }
 
-extern struct list_head batadv_hardif_list;
 extern unsigned int batadv_hardif_generation;
 
 extern struct workqueue_struct *batadv_event_workqueue;
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index e3d47f3e3b22..c1e8a074fb70 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -1211,7 +1211,9 @@ batadv_netlink_get_hardif_from_ifindex(struct batadv_priv *bat_priv,
 	if (!hard_dev)
 		return ERR_PTR(-ENODEV);
 
+	rtnl_lock();
 	hard_iface = batadv_hardif_get_by_netdev(hard_dev);
+	rtnl_unlock();
 	if (!hard_iface)
 		goto err_put_harddev;
 
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index b1f9f8964c3f..1671380b3792 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -214,9 +214,6 @@ struct batadv_wifi_net_device_state {
  * struct batadv_hard_iface - network device known to batman-adv
  */
 struct batadv_hard_iface {
-	/** @list: list node for batadv_hardif_list */
-	struct list_head list;
-
 	/** @if_status: status of the interface for batman-adv */
 	char if_status;
 
-- 
2.54.0

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

[Nora Schiffer]

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 <sven@narfation.org>
Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

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

[PATCH batadv v5 4/6] batman-adv: remove BATADV_IF_NOT_IN_USE hardif state

[Nora Schiffer]

With hardifs only existing while an interface is part of a mesh, the
BATADV_IF_NOT_IN_USE state has become redundant.

Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

v2-v5: no changes


 net/batman-adv/bat_iv_ogm.c     | 3 +--
 net/batman-adv/bat_v_elp.c      | 3 +--
 net/batman-adv/hard-interface.c | 9 ---------
 net/batman-adv/hard-interface.h | 6 ------
 net/batman-adv/originator.c     | 4 ----
 5 files changed, 2 insertions(+), 23 deletions(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index bb2f012b454e..4514c51bba77 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -910,8 +910,7 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 
 static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface)
 {
-	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE ||
-	    hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
+	if (hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
 		return;
 
 	mutex_lock(&hard_iface->bat_iv.ogm_buff_mutex);
diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c
index 4841f0f1a9b1..bc3e4f264afa 100644
--- a/net/batman-adv/bat_v_elp.c
+++ b/net/batman-adv/bat_v_elp.c
@@ -311,8 +311,7 @@ static void batadv_v_elp_periodic_work(struct work_struct *work)
 		goto out;
 
 	/* we are in the process of shutting this interface down */
-	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE ||
-	    hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
+	if (hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
 		goto out;
 
 	/* the interface was enabled but may not be ready yet */
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index a0b8b06f9a64..86010bc32818 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -547,9 +547,6 @@ static void batadv_check_known_mac_addr(const struct batadv_hard_iface *hard_ifa
 		if (tmp_hard_iface == hard_iface)
 			continue;
 
-		if (tmp_hard_iface->if_status == BATADV_IF_NOT_IN_USE)
-			continue;
-
 		if (!batadv_compare_eth(tmp_hard_iface->net_dev->dev_addr,
 					hard_iface->net_dev->dev_addr))
 			continue;
@@ -575,9 +572,6 @@ static void batadv_hardif_recalc_extra_skbroom(struct net_device *mesh_iface)
 
 	rcu_read_lock();
 	netdev_for_each_lower_private_rcu(mesh_iface, hard_iface, iter) {
-		if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
-			continue;
-
 		lower_header_len = max_t(unsigned short, lower_header_len,
 					 hard_iface->net_dev->hard_header_len);
 
@@ -1065,9 +1059,6 @@ static int batadv_hard_if_event(struct notifier_block *this,
 			batadv_update_min_mtu(hard_iface->mesh_iface);
 		break;
 	case NETDEV_CHANGEADDR:
-		if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
-			goto hardif_put;
-
 		batadv_check_known_mac_addr(hard_iface);
 
 		bat_priv = netdev_priv(hard_iface->mesh_iface);
diff --git a/net/batman-adv/hard-interface.h b/net/batman-adv/hard-interface.h
index aa9275dec097..935f47ca9a48 100644
--- a/net/batman-adv/hard-interface.h
+++ b/net/batman-adv/hard-interface.h
@@ -21,12 +21,6 @@
  * enum batadv_hard_if_state - State of a hard interface
  */
 enum batadv_hard_if_state {
-	/**
-	 * @BATADV_IF_NOT_IN_USE: interface is not used as slave interface of a
-	 * batman-adv mesh interface
-	 */
-	BATADV_IF_NOT_IN_USE,
-
 	/**
 	 * @BATADV_IF_TO_BE_REMOVED: interface will be removed from mesh
 	 * interface
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 9b38bd9e8da7..48f837cf665a 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -1033,7 +1033,6 @@ batadv_purge_neigh_ifinfo(struct batadv_priv *bat_priv,
 
 		/* don't purge if the interface is not (going) down */
 		if (if_outgoing->if_status != BATADV_IF_INACTIVE &&
-		    if_outgoing->if_status != BATADV_IF_NOT_IN_USE &&
 		    if_outgoing->if_status != BATADV_IF_TO_BE_REMOVED)
 			continue;
 
@@ -1077,7 +1076,6 @@ batadv_purge_orig_ifinfo(struct batadv_priv *bat_priv,
 
 		/* don't purge if the interface is not (going) down */
 		if (if_outgoing->if_status != BATADV_IF_INACTIVE &&
-		    if_outgoing->if_status != BATADV_IF_NOT_IN_USE &&
 		    if_outgoing->if_status != BATADV_IF_TO_BE_REMOVED)
 			continue;
 
@@ -1127,10 +1125,8 @@ batadv_purge_orig_neighbors(struct batadv_priv *bat_priv,
 
 		if (batadv_has_timed_out(last_seen, BATADV_PURGE_TIMEOUT) ||
 		    if_incoming->if_status == BATADV_IF_INACTIVE ||
-		    if_incoming->if_status == BATADV_IF_NOT_IN_USE ||
 		    if_incoming->if_status == BATADV_IF_TO_BE_REMOVED) {
 			if (if_incoming->if_status == BATADV_IF_INACTIVE ||
-			    if_incoming->if_status == BATADV_IF_NOT_IN_USE ||
 			    if_incoming->if_status == BATADV_IF_TO_BE_REMOVED)
 				batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 					   "neighbor purge: originator %pM, neighbor: %pM, iface: %s\n",
-- 
2.54.0

[PATCH batadv v5 5/6] batman-adv: move hardif generation counter into batadv_priv

[Nora Schiffer]

The counter doesn't need to be global.

Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

v2-v5: no changes


 net/batman-adv/hard-interface.c | 4 ++--
 net/batman-adv/main.c           | 1 -
 net/batman-adv/main.h           | 2 --
 net/batman-adv/netlink.c        | 2 +-
 net/batman-adv/types.h          | 3 +++
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 86010bc32818..9b8108d464db 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -774,7 +774,7 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 	hard_iface->mesh_iface = mesh_iface;
 	bat_priv = netdev_priv(hard_iface->mesh_iface);
 
-	batadv_hardif_generation++;
+	bat_priv->hardif_generation++;
 	ret = netdev_master_upper_dev_link(hard_iface->net_dev,
 					   mesh_iface, hard_iface, NULL, NULL);
 	if (ret)
@@ -865,7 +865,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 	batadv_purge_orig_ref(bat_priv);
 	batadv_purge_outstanding_packets(bat_priv, hard_iface);
 
-	batadv_hardif_generation++;
+	bat_priv->hardif_generation++;
 	netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->mesh_iface);
 	batadv_hardif_recalc_extra_skbroom(hard_iface->mesh_iface);
 
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 1d82f3a841a1..badc1df0af1d 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -59,7 +59,6 @@
 #include "tp_meter.h"
 #include "translation-table.h"
 
-unsigned int batadv_hardif_generation;
 static int (*batadv_rx_handler[256])(struct sk_buff *skb,
 				     struct batadv_hard_iface *recv_if);
 
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index e34145047a34..e738758ee4a7 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -226,8 +226,6 @@ static inline int batadv_print_vid(unsigned short vid)
 		return -1;
 }
 
-extern unsigned int batadv_hardif_generation;
-
 extern struct workqueue_struct *batadv_event_workqueue;
 
 int batadv_mesh_init(struct net_device *mesh_iface);
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index c1e8a074fb70..4b43b3fab72c 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -968,7 +968,7 @@ batadv_netlink_dump_hardif(struct sk_buff *msg, struct netlink_callback *cb)
 	bat_priv = netdev_priv(mesh_iface);
 
 	rtnl_lock();
-	cb->seq = batadv_hardif_generation << 1 | 1;
+	cb->seq = bat_priv->hardif_generation << 1 | 1;
 
 	netdev_for_each_lower_private(mesh_iface, hard_iface, iter) {
 		if (i++ < skip)
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 1671380b3792..e1463a029e83 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1676,6 +1676,9 @@ struct batadv_priv {
 	/** @tp_num: number of currently active tp sessions */
 	atomic_t tp_num;
 
+	/** @hardif_generation: generation counter added to netlink hardif dumps */
+	unsigned int hardif_generation;
+
 	/** @orig_work: work queue callback item for orig node purging */
 	struct delayed_work orig_work;
 
-- 
2.54.0

[PATCH batadv v5 6/6] batman-adv: drop unneeded goto and initialization from batadv_hardif_disable_interface()

[Nora Schiffer]

The only use of the label was too early for primary_if to be set
anyways.

Also move the put of primary_if further up to hold the reference only as
long as necessary, hopefully avoiding the need to re-introduce the goto
label with future code changes.

Signed-off-by: Nora Schiffer <neocturne@universe-factory.net>
---

v5: new patch


 net/batman-adv/hard-interface.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 9b8108d464db..6fc49ad47fd8 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -835,14 +835,14 @@ int batadv_hardif_enable_interface(struct net_device *net_dev,
 void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->mesh_iface);
-	struct batadv_hard_iface *primary_if = NULL;
+	struct batadv_hard_iface *primary_if;
 
 	ASSERT_RTNL();
 
 	batadv_hardif_deactivate_interface(hard_iface);
 
 	if (hard_iface->if_status != BATADV_IF_INACTIVE)
-		goto out;
+		return;
 
 	batadv_info(hard_iface->mesh_iface, "Removing interface: %s\n",
 		    hard_iface->net_dev->name);
@@ -857,6 +857,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 
 		batadv_hardif_put(new_if);
 	}
+	batadv_hardif_put(primary_if);
 
 	bat_priv->algo_ops->iface.disable(hard_iface);
 	hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
@@ -874,9 +875,6 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 		batadv_gw_check_client_stop(bat_priv);
 
 	batadv_hardif_put(hard_iface);
-
-out:
-	batadv_hardif_put(primary_if);
 }
 
 /**
-- 
2.54.0

Re: [PATCH batadv v5 0/6] batman-adv: drop global hard interface list

[Sven Eckelmann]

On Sun, 28 Jun 2026 17:07:27 +0200, Nora Schiffer wrote:
> batman-adv: drop global hard interface list
> 
> Cover letter from Sven's v4:
> 
> The global hard interface list was used in the past to provide and sysfs
> (debugfs, procfs) based configuration interface. This requirement is gone
> after it was switched to generic netlink and NETLINK_ROUTE. And after the
> wifi-flags cache was introduced, it is also no longer used to get
> non-batman-adv attached interface information (for ap_isolation and
> re-broadcast configuration).
> 
> [...]

Applied, thanks!

[1/6] batman-adv: create hardif only for netdevs that are part of a mesh
      https://git.open-mesh.org/batadv/c/fcba102e0e4a
[2/6] batman-adv: remove global hardif list
      https://git.open-mesh.org/batadv/c/49e9de6e124f
[3/6] batman-adv: make hard_iface->mesh_iface immutable
      https://git.open-mesh.org/batadv/c/f846e779532e
[4/6] batman-adv: remove BATADV_IF_NOT_IN_USE hardif state
      https://git.open-mesh.org/batadv/c/48ea7b6b7b94
[5/6] batman-adv: move hardif generation counter into batadv_priv
      https://git.open-mesh.org/batadv/c/cbda6a6cf2a5
[6/6] batman-adv: drop unneeded goto and initialization from batadv_hardif_disable_interface()
      https://git.open-mesh.org/batadv/c/2b429dbc50b4

Best regards,
-- 
Sven Eckelmann <sven@narfation.org>