[PATCH net 08/11] batman-adv: iv: recover OGM scheduling after forward packet error

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

When batadv_iv_ogm_schedule_buff() fails to allocate and queue a forward
packet for OGM transmission, the work item that drives periodic OGM
scheduling is never re-armed. This silently halts transmission of the
node's own OGMs on the affected interface — only OGMs from other peers
continue to be aggregated and forwarded.

Fix this by tracking whether batadv_iv_ogm_queue_add() (and transitively
batadv_iv_ogm_aggregate_new()) successfully scheduled a forward packet.
When scheduling fails, batadv_iv_ogm_schedule_buff() falls back to queuing
a dedicated recovery work item (reschedule_work) that fires after one
originator interval and calls batadv_iv_ogm_schedule() again.

Cc: stable@kernel.org
Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/bat_iv_ogm.c | 76 +++++++++++++++++++++++++++----------
 net/batman-adv/types.h      |  3 ++
 2 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 7ad26128b5f7c..b8b1b997960a9 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -224,6 +224,8 @@ static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface)
 	hard_iface->bat_iv.ogm_buff = NULL;
 
 	mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex);
+
+	cancel_delayed_work_sync(&hard_iface->bat_iv.reschedule_work);
 }
 
 static void batadv_iv_ogm_iface_update_mac(struct batadv_hard_iface *hard_iface)
@@ -536,8 +538,10 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
  * @if_incoming: interface where the packet was received
  * @if_outgoing: interface for which the retransmission should be considered
  * @own_packet: true if it is a self-generated ogm
+ *
+ * Return: whether forward packet was scheduled
  */
-static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
+static bool batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
 					int packet_len, unsigned long send_time,
 					bool direct_link,
 					struct batadv_hard_iface *if_incoming,
@@ -561,13 +565,13 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
 
 	skb = netdev_alloc_skb_ip_align(NULL, skb_size);
 	if (!skb)
-		return;
+		return false;
 
 	forw_packet_aggr = batadv_forw_packet_alloc(if_incoming, if_outgoing,
 						    queue_left, bat_priv, skb);
 	if (!forw_packet_aggr) {
 		kfree_skb(skb);
-		return;
+		return false;
 	}
 
 	forw_packet_aggr->skb->priority = TC_PRIO_CONTROL;
@@ -590,6 +594,8 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
 			  batadv_iv_send_outstanding_bat_ogm_packet);
 
 	batadv_forw_packet_ogmv1_queue(bat_priv, forw_packet_aggr, send_time);
+
+	return true;
 }
 
 /* aggregate a new packet into the existing ogm packet */
@@ -617,8 +623,10 @@ static void batadv_iv_ogm_aggregate(struct batadv_forw_packet *forw_packet_aggr,
  * @if_outgoing: interface for which the retransmission should be considered
  * @own_packet: true if it is a self-generated ogm
  * @send_time: timestamp (jiffies) when the packet is to be sent
+ *
+ * Return: whether forward packet was scheduled
  */
-static void batadv_iv_ogm_queue_add(struct batadv_priv *bat_priv,
+static bool batadv_iv_ogm_queue_add(struct batadv_priv *bat_priv,
 				    unsigned char *packet_buff,
 				    int packet_len,
 				    struct batadv_hard_iface *if_incoming,
@@ -670,14 +678,16 @@ static void batadv_iv_ogm_queue_add(struct batadv_priv *bat_priv,
 		if (!own_packet && atomic_read(&bat_priv->aggregated_ogms))
 			send_time += max_aggregation_jiffies;
 
-		batadv_iv_ogm_aggregate_new(packet_buff, packet_len,
-					    send_time, direct_link,
-					    if_incoming, if_outgoing,
-					    own_packet);
+		return batadv_iv_ogm_aggregate_new(packet_buff, packet_len,
+						   send_time, direct_link,
+						   if_incoming, if_outgoing,
+						   own_packet);
 	} else {
 		batadv_iv_ogm_aggregate(forw_packet_aggr, packet_buff,
 					packet_len, direct_link);
 		spin_unlock_bh(&bat_priv->forw_bat_list_lock);
+
+		return true;
 	}
 }
 
@@ -790,6 +800,8 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 	u32 seqno;
 	u16 tvlv_len = 0;
 	unsigned long send_time;
+	bool reschedule = false;
+	bool scheduled;
 	int ret;
 
 	lockdep_assert_held(&hard_iface->bat_iv.ogm_buff_mutex);
@@ -818,11 +830,8 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 						       ogm_buff_len,
 						       BATADV_OGM_HLEN);
 		if (ret < 0) {
-			/* OGMs must be queued even when the buffer allocation for
-			 * TVLVs failed. just fall back to the non-TVLV version
-			 */
-			ret = 0;
-			*ogm_buff_len = BATADV_OGM_HLEN;
+			reschedule = true;
+			goto out;
 		}
 
 		tvlv_len = ret;
@@ -844,8 +853,11 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 		/* OGMs from secondary interfaces are only scheduled on their
 		 * respective interfaces.
 		 */
-		batadv_iv_ogm_queue_add(bat_priv, *ogm_buff, *ogm_buff_len,
-					hard_iface, hard_iface, 1, send_time);
+		scheduled = batadv_iv_ogm_queue_add(bat_priv, *ogm_buff, *ogm_buff_len,
+						    hard_iface, hard_iface, 1, send_time);
+		if (!scheduled)
+			reschedule = true;
+
 		goto out;
 	}
 
@@ -857,15 +869,28 @@ static void batadv_iv_ogm_schedule_buff(struct batadv_hard_iface *hard_iface)
 		if (!kref_get_unless_zero(&tmp_hard_iface->refcount))
 			continue;
 
-		batadv_iv_ogm_queue_add(bat_priv, *ogm_buff,
-					*ogm_buff_len, hard_iface,
-					tmp_hard_iface, 1, send_time);
-
+		scheduled = batadv_iv_ogm_queue_add(bat_priv, *ogm_buff,
+						    *ogm_buff_len, hard_iface,
+						    tmp_hard_iface, 1, send_time);
 		batadv_hardif_put(tmp_hard_iface);
+
+		if (!scheduled && tmp_hard_iface == hard_iface)
+			reschedule = true;
 	}
 	rcu_read_unlock();
 
 out:
+	if (reschedule) {
+		/* there was a failure scheduling the own forward packet.
+		 * as result, the batadv_iv_send_outstanding_bat_ogm_packet()
+		 * work item is no longer scheduled. it is therefore necessary
+		 * to reschedule it manually
+		 */
+		queue_delayed_work(batadv_event_workqueue,
+				   &hard_iface->bat_iv.reschedule_work,
+				   msecs_to_jiffies(atomic_read(&bat_priv->orig_interval)));
+	}
+
 	batadv_hardif_put(primary_if);
 }
 
@@ -880,6 +905,17 @@ static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface)
 	mutex_unlock(&hard_iface->bat_iv.ogm_buff_mutex);
 }
 
+static void batadv_iv_ogm_reschedule(struct work_struct *work)
+{
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct batadv_hard_iface *hard_iface;
+
+	hard_iface = container_of(delayed_work,
+				  struct batadv_hard_iface,
+				  bat_iv.reschedule_work);
+	batadv_iv_ogm_schedule(hard_iface);
+}
+
 /**
  * batadv_iv_orig_ifinfo_sum() - Get bcast_own sum for originator over interface
  * @orig_node: originator which reproadcasted the OGMs directly
@@ -2272,6 +2308,8 @@ batadv_iv_ogm_neigh_is_sob(struct batadv_neigh_node *neigh1,
 
 static void batadv_iv_iface_enabled(struct batadv_hard_iface *hard_iface)
 {
+	INIT_DELAYED_WORK(&hard_iface->bat_iv.reschedule_work, batadv_iv_ogm_reschedule);
+
 	/* begin scheduling originator messages on that interface */
 	batadv_iv_ogm_schedule(hard_iface);
 }
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index fb0e4cb89d79a..821ada05d86a7 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -83,6 +83,9 @@ struct batadv_hard_iface_bat_iv {
 	/** @ogm_seqno: OGM sequence number - used to identify each OGM */
 	atomic_t ogm_seqno;
 
+	/** @reschedule_work: recover OGM schedule after schedule error */
+	struct delayed_work reschedule_work;
+
 	/** @ogm_buff_mutex: lock protecting ogm_buff and ogm_buff_len */
 	struct mutex ogm_buff_mutex;
 };
-- 
2.47.3