[B.A.T.M.A.N.] [PATCH 12/13] batman-adv: Generic sequence number checking for data packets

["Linus Lüssing" <linus.luessing@ascom.ch>]

This reduces the size of recv_bcast_packet, increasing its readability.
It further introduces a generic function for duplicate checking for data
packets (which might later be used for multicast or promiscous unicast
packet handling or other packets).

Signed-off-by: Linus Lüssing <linus.luessing@ascom.ch>
---
 originator.c |    2 +-
 routing.c    |   60 ++++++++++++++++++++++++++++++++++-----------------------
 types.h      |   10 ++++++--
 3 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/batman-adv/originator.c b/batman-adv/originator.c
index af3f338..4845421 100644
--- a/batman-adv/originator.c
+++ b/batman-adv/originator.c
@@ -211,7 +211,7 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
 	memcpy(orig_node->orig, addr, ETH_ALEN);
 	orig_node->router = NULL;
 	orig_node->hna_buff = NULL;
-	orig_node->bcast_seqno_reset = jiffies - 1
+	orig_node->bcast_seqno_state.seqno_reset = jiffies - 1
 					- msecs_to_jiffies(RESET_PROTECTION_MS);
 	orig_node->batman_seqno_reset = jiffies - 1
 					- msecs_to_jiffies(RESET_PROTECTION_MS);
diff --git a/batman-adv/routing.c b/batman-adv/routing.c
index 4aa7fb5..afbeef8 100644
--- a/batman-adv/routing.c
+++ b/batman-adv/routing.c
@@ -1292,6 +1292,36 @@ static int check_unicast_packet(struct sk_buff *skb, int hdr_size)
 	return 0;
 }
 
+static inline int check_duplicate(struct bat_priv *bat_priv, uint32_t seqno,
+				  struct seqno_state *seqno_state,
+				  spinlock_t *seqno_lock)
+{
+	int32_t seq_diff;
+	int ret = NET_RX_DROP;
+
+	spin_lock_bh(seqno_lock);
+
+	/* check whether the packet is a duplicate */
+	if (get_bit_status(seqno_state->bits, seqno_state->last_seqno, seqno))
+		goto spin_unlock;
+
+	seq_diff = seqno - seqno_state->last_seqno;
+
+	/* check whether the packet is old and the host just restarted. */
+	if (window_protected(bat_priv, seq_diff, &seqno_state->seqno_reset))
+		goto spin_unlock;
+
+	/* mark broadcast in flood history, update window position
+	 * if required. */
+	if (bit_get_packet(bat_priv, seqno_state->bits, seq_diff, 1))
+		seqno_state->last_seqno = seqno;
+
+	ret = NET_RX_SUCCESS;
+spin_unlock:
+	spin_unlock_bh(seqno_lock);
+	return ret;
+}
+
 int route_unicast_packet(int bonding_mode, struct sk_buff *skb,
 			 struct batman_if *recv_if,
 			 struct orig_node *orig_node)
@@ -1444,7 +1474,6 @@ int recv_bcast_packet(struct sk_buff *skb, struct batman_if *recv_if)
 	struct ethhdr *ethhdr;
 	int hdr_size = sizeof(struct bcast_packet);
 	int ret = NET_RX_DROP;
-	int32_t seq_diff;
 
 	/* drop packet if it has not necessary minimum size */
 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
@@ -1474,26 +1503,13 @@ int recv_bcast_packet(struct sk_buff *skb, struct batman_if *recv_if)
 	if (!orig_node)
 		goto out;
 
-	spin_lock_bh(&orig_node->bcast_seqno_lock);
+	ret = check_duplicate(bat_priv, ntohl(bcast_packet->seqno),
+			      &orig_node->bcast_seqno_state,
+			      &orig_node->bcast_seqno_lock);
 
-	/* check whether the packet is a duplicate */
-	if (get_bit_status(orig_node->bcast_bits, orig_node->last_bcast_seqno,
-			   ntohl(bcast_packet->seqno)))
-		goto spin_unlock;
-
-	seq_diff = ntohl(bcast_packet->seqno) - orig_node->last_bcast_seqno;
-
-	/* check whether the packet is old and the host just restarted. */
-	if (window_protected(bat_priv, seq_diff,
-			     &orig_node->bcast_seqno_reset))
-		goto spin_unlock;
-
-	/* mark broadcast in flood history, update window position
-	 * if required. */
-	if (bit_get_packet(bat_priv, orig_node->bcast_bits, seq_diff, 1))
-		orig_node->last_bcast_seqno = ntohl(bcast_packet->seqno);
-
-	spin_unlock_bh(&orig_node->bcast_seqno_lock);
+	kref_put(&orig_node->refcount, orig_node_free_ref);
+	if (ret == NET_RX_DROP)
+		goto out;
 
 	/* rebroadcast packet */
 	add_bcast_packet_to_list(bat_priv, skb);
@@ -1503,11 +1519,7 @@ int recv_bcast_packet(struct sk_buff *skb, struct batman_if *recv_if)
 	ret = NET_RX_SUCCESS;
 	goto out;
 
-spin_unlock:
-	spin_unlock_bh(&orig_node->bcast_seqno_lock);
 out:
-	if (orig_node)
-		kref_put(&orig_node->refcount, orig_node_free_ref);
 	return ret;
 }
 
diff --git a/batman-adv/types.h b/batman-adv/types.h
index 5401498..5a2035a 100644
--- a/batman-adv/types.h
+++ b/batman-adv/types.h
@@ -49,6 +49,12 @@ struct batman_if {
 	struct rcu_head rcu;
 };
 
+struct seqno_state {
+	unsigned long seqno_reset;
+	uint32_t last_seqno;
+	unsigned long bits[NUM_WORDS];
+};
+
 /**
  *	orig_node - structure for orig_list maintaining nodes of mesh
  *	@primary_addr: hosts primary interface address
@@ -71,7 +77,6 @@ struct orig_node {
 	unsigned long *bcast_own;
 	uint8_t *bcast_own_sum;
 	unsigned long last_valid;
-	unsigned long bcast_seqno_reset;
 	unsigned long batman_seqno_reset;
 	uint8_t gw_flags;
 	uint8_t flags;
@@ -79,14 +84,13 @@ struct orig_node {
 	int16_t hna_buff_len;
 	uint32_t last_real_seqno;
 	uint8_t last_ttl;
-	unsigned long bcast_bits[NUM_WORDS];
-	uint32_t last_bcast_seqno;
 	struct hlist_head neigh_list;
 	struct list_head frag_list;
 	spinlock_t neigh_list_lock; /* protects neighbor list */
 	struct kref refcount;
 	struct bat_priv *bat_priv;
 	unsigned long last_frag_packet;
+	struct seqno_state bcast_seqno_state;
 	spinlock_t ogm_cnt_lock; /* protects: bcast_own, bcast_own_sum,
 				  * neigh_node->real_bits,
 				  * neigh_node->real_packet_count */
-- 
1.7.2.3