netdev - [PATCH 06/10] batman-adv: Limit number of aggregated packets directly

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Message-Id: <20250313164519.72808-7-sw@simonwunderlich.de>
Date: Thu, 13 Mar 2025 17:45:15 +0100
From: Simon Wunderlich <sw@...onwunderlich.de>
To: kuba@...nel.org,
	davem@...emloft.net
Cc: netdev@...r.kernel.org,
	b.a.t.m.a.n@...ts.open-mesh.org,
	Sven Eckelmann <sven@...fation.org>,
	Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 06/10] batman-adv: Limit number of aggregated packets directly

From: Sven Eckelmann <sven@...fation.org>

The currently selected size in BATADV_MAX_AGGREGATION_BYTES (512) is chosen
such that the number of possible aggregated packets is lower than 32. This
number must be limited so that the type of
batadv_forw_packet->direct_link_flags has enough bits to represent each
packet (with the size of at least 24 bytes).

This requirement is better implemented in code instead of having it inside
a comment.

Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
---
 net/batman-adv/bat_iv_ogm.c | 4 ++++
 net/batman-adv/main.h       | 3 ---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 8513f6661dd1..b715f7343ffd 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -446,6 +446,7 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
 	struct batadv_ogm_packet *batadv_ogm_packet;
 	int aggregated_bytes = forw_packet->packet_len + packet_len;
 	struct batadv_hard_iface *primary_if = NULL;
+	u8 packet_num = forw_packet->num_packets + 1;
 	bool res = false;
 	unsigned long aggregation_end_time;
 
@@ -468,6 +469,9 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
 	if (aggregated_bytes > BATADV_MAX_AGGREGATION_BYTES)
 		return false;
 
+	if (packet_num >= BITS_PER_TYPE(forw_packet->direct_link_flags))
+		return false;
+
 	/* packet is not leaving on the same interface. */
 	if (forw_packet->if_outgoing != if_outgoing)
 		return false;
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index 5adefdfc69bc..c08c96b5b8b1 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -104,9 +104,6 @@
  */
 #define BATADV_TQ_SIMILARITY_THRESHOLD 50
 
-/* should not be bigger than 512 bytes or change the size of
- * forw_packet->direct_link_flags
- */
 #define BATADV_MAX_AGGREGATION_BYTES 512
 #define BATADV_MAX_AGGREGATION_MS 100
 
-- 
2.39.5