batman-adv: Introduce forward packet creation helper

This patch abstracts the forward packet creation into the new function
batadv_forw_packet_alloc().

The queue counting and interface reference counters are now handled
internally within batadv_forw_packet_alloc() and its
batadv_forw_packet_free() counterpart. This should reduce the risk of
having reference/queue counting bugs again and should increase
code readibility.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 57e0af9..a40cdf2 100644 (file)
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -675,19 +675,12 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
        struct batadv_forw_packet *forw_packet_aggr;
        unsigned char *skb_buff;
        unsigned int skb_size;
+       atomic_t *queue_left = own_packet ? NULL : &bat_priv->batman_queue_left;
 
-       /* own packet should always be scheduled */
-       if (!own_packet) {
-               if (!batadv_atomic_dec_not_zero(&bat_priv->batman_queue_left)) {
-                       batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
-                                  "batman packet queue full\n");
-                       return;
-               }
-       }
-
-       forw_packet_aggr = kmalloc(sizeof(*forw_packet_aggr), GFP_ATOMIC);
+       forw_packet_aggr = batadv_forw_packet_alloc(if_incoming, if_outgoing,
+                                                   queue_left, bat_priv);
        if (!forw_packet_aggr)
-               goto out_nomem;
+               return;
 
        if (atomic_read(&bat_priv->aggregated_ogms) &&
            packet_len < BATADV_MAX_AGGREGATION_BYTES)
@@ -698,8 +691,11 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
        skb_size += ETH_HLEN;
 
        forw_packet_aggr->skb = netdev_alloc_skb_ip_align(NULL, skb_size);
-       if (!forw_packet_aggr->skb)
-               goto out_free_forw_packet;
+       if (!forw_packet_aggr->skb) {
+               batadv_forw_packet_free(forw_packet_aggr);
+               return;
+       }
+
        forw_packet_aggr->skb->priority = TC_PRIO_CONTROL;
        skb_reserve(forw_packet_aggr->skb, ETH_HLEN);
 
@@ -707,12 +703,7 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
        forw_packet_aggr->packet_len = packet_len;
        memcpy(skb_buff, packet_buff, packet_len);
 
-       kref_get(&if_incoming->refcount);
-       kref_get(&if_outgoing->refcount);
        forw_packet_aggr->own = own_packet;
-       forw_packet_aggr->if_incoming = if_incoming;
-       forw_packet_aggr->if_outgoing = if_outgoing;
-       forw_packet_aggr->num_packets = 0;
        forw_packet_aggr->direct_link_flags = BATADV_NO_FLAGS;
        forw_packet_aggr->send_time = send_time;
 
@@ -731,13 +722,6 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
        queue_delayed_work(batadv_event_workqueue,
                           &forw_packet_aggr->delayed_work,
                           send_time - jiffies);
-
-       return;
-out_free_forw_packet:
-       kfree(forw_packet_aggr);
-out_nomem:
-       if (!own_packet)
-               atomic_inc(&bat_priv->batman_queue_left);
 }
 
 /* aggregate a new packet into the existing ogm packet */
@@ -1820,10 +1804,6 @@ static void batadv_iv_send_outstanding_bat_ogm_packet(struct work_struct *work)
                batadv_iv_ogm_schedule(forw_packet->if_incoming);
 
 out:
-       /* don't count own packet */
-       if (!forw_packet->own)
-               atomic_inc(&bat_priv->batman_queue_left);
-
        batadv_forw_packet_free(forw_packet);
 }
 

diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index 6191159..33d8bd1 100644 (file)
--- a/net/batman-adv/send.c
+++ b/net/batman-adv/send.c
@@ -439,6 +439,13 @@ int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
                                       BATADV_P_DATA, orig_node, vid);
 }
 
+/**
+ * batadv_forw_packet_free - free a forwarding packet
+ * @forw_packet: The packet to free
+ *
+ * This frees a forwarding packet and releases any resources it might
+ * have claimed.
+ */
 void batadv_forw_packet_free(struct batadv_forw_packet *forw_packet)
 {
        kfree_skb(forw_packet->skb);
@@ -446,9 +453,73 @@ void batadv_forw_packet_free(struct batadv_forw_packet *forw_packet)
                batadv_hardif_put(forw_packet->if_incoming);
        if (forw_packet->if_outgoing)
                batadv_hardif_put(forw_packet->if_outgoing);
+       if (forw_packet->queue_left)
+               atomic_inc(forw_packet->queue_left);
        kfree(forw_packet);
 }
 
+/**
+ * batadv_forw_packet_alloc - allocate a forwarding packet
+ * @if_incoming: The (optional) if_incoming to be grabbed
+ * @if_outgoing: The (optional) if_outgoing to be grabbed
+ * @queue_left: The (optional) queue counter to decrease
+ * @bat_priv: The bat_priv for the mesh of this forw_packet
+ *
+ * Allocates a forwarding packet and tries to get a reference to the
+ * (optional) if_incoming, if_outgoing and queue_left. If queue_left
+ * is NULL then bat_priv is optional, too.
+ *
+ * Return: An allocated forwarding packet on success, NULL otherwise.
+ */
+struct batadv_forw_packet *
+batadv_forw_packet_alloc(struct batadv_hard_iface *if_incoming,
+                        struct batadv_hard_iface *if_outgoing,
+                        atomic_t *queue_left,
+                        struct batadv_priv *bat_priv)
+{
+       struct batadv_forw_packet *forw_packet;
+       const char *qname;
+
+       if (queue_left && !batadv_atomic_dec_not_zero(queue_left)) {
+               qname = "unknown";
+
+               if (queue_left == &bat_priv->bcast_queue_left)
+                       qname = "bcast";
+
+               if (queue_left == &bat_priv->batman_queue_left)
+                       qname = "batman";
+
+               batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+                          "%s queue is full\n", qname);
+
+               return NULL;
+       }
+
+       forw_packet = kmalloc(sizeof(*forw_packet), GFP_ATOMIC);
+       if (!forw_packet)
+               goto err;
+
+       if (if_incoming)
+               kref_get(&if_incoming->refcount);
+
+       if (if_outgoing)
+               kref_get(&if_outgoing->refcount);
+
+       forw_packet->skb = NULL;
+       forw_packet->queue_left = queue_left;
+       forw_packet->if_incoming = if_incoming;
+       forw_packet->if_outgoing = if_outgoing;
+       forw_packet->num_packets = 0;
+
+       return forw_packet;
+
+err:
+       if (queue_left)
+               atomic_inc(queue_left);
+
+       return NULL;
+}
+
 static void
 _batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
                                 struct batadv_forw_packet *forw_packet,
@@ -487,24 +558,20 @@ int batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
        struct batadv_bcast_packet *bcast_packet;
        struct sk_buff *newskb;
 
-       if (!batadv_atomic_dec_not_zero(&bat_priv->bcast_queue_left)) {
-               batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
-                          "bcast packet queue full\n");
-               goto out;
-       }
-
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
-               goto out_and_inc;
-
-       forw_packet = kmalloc(sizeof(*forw_packet), GFP_ATOMIC);
+               goto err;
 
+       forw_packet = batadv_forw_packet_alloc(primary_if, NULL,
+                                              &bat_priv->bcast_queue_left,
+                                              bat_priv);
+       batadv_hardif_put(primary_if);
        if (!forw_packet)
-               goto out_and_inc;
+               goto err;
 
        newskb = skb_copy(skb, GFP_ATOMIC);
        if (!newskb)
-               goto packet_free;
+               goto err_packet_free;
 
        /* as we have a copy now, it is safe to decrease the TTL */
        bcast_packet = (struct batadv_bcast_packet *)newskb->data;
@@ -513,11 +580,6 @@ int batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
        skb_reset_mac_header(newskb);
 
        forw_packet->skb = newskb;
-       forw_packet->if_incoming = primary_if;
-       forw_packet->if_outgoing = NULL;
-
-       /* how often did we send the bcast packet ? */
-       forw_packet->num_packets = 0;
 
        INIT_DELAYED_WORK(&forw_packet->delayed_work,
                          batadv_send_outstanding_bcast_packet);
@@ -525,13 +587,9 @@ int batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
        _batadv_add_bcast_packet_to_list(bat_priv, forw_packet, delay);
        return NETDEV_TX_OK;
 
-packet_free:
-       kfree(forw_packet);
-out_and_inc:
-       atomic_inc(&bat_priv->bcast_queue_left);
-out:
-       if (primary_if)
-               batadv_hardif_put(primary_if);
+err_packet_free:
+       batadv_forw_packet_free(forw_packet);
+err:
        return NETDEV_TX_BUSY;
 }
 
@@ -592,7 +650,6 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
 
 out:
        batadv_forw_packet_free(forw_packet);
-       atomic_inc(&bat_priv->bcast_queue_left);
 }
 
 void
@@ -633,9 +690,6 @@ batadv_purge_outstanding_packets(struct batadv_priv *bat_priv,
 
                if (pending) {
                        hlist_del(&forw_packet->list);
-                       if (!forw_packet->own)
-                               atomic_inc(&bat_priv->bcast_queue_left);
-
                        batadv_forw_packet_free(forw_packet);
                }
        }
@@ -663,9 +717,6 @@ batadv_purge_outstanding_packets(struct batadv_priv *bat_priv,
 
                if (pending) {
                        hlist_del(&forw_packet->list);
-                       if (!forw_packet->own)
-                               atomic_inc(&bat_priv->batman_queue_left);
-
                        batadv_forw_packet_free(forw_packet);
                }
        }

diff --git a/net/batman-adv/send.h b/net/batman-adv/send.h
index 7cecb75..999f786 100644 (file)
--- a/net/batman-adv/send.h
+++ b/net/batman-adv/send.h
@@ -28,6 +28,12 @@
 struct sk_buff;
 
 void batadv_forw_packet_free(struct batadv_forw_packet *forw_packet);
+struct batadv_forw_packet *
+batadv_forw_packet_alloc(struct batadv_hard_iface *if_incoming,
+                        struct batadv_hard_iface *if_outgoing,
+                        atomic_t *queue_left,
+                        struct batadv_priv *bat_priv);
+
 int batadv_send_skb_to_orig(struct sk_buff *skb,
                            struct batadv_orig_node *orig_node,
                            struct batadv_hard_iface *recv_if);

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 54710c7..72806a3 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1375,6 +1375,7 @@ struct batadv_skb_cb {
  *  locally generated packet
  * @if_outgoing: packet where the packet should be sent to, or NULL if
  *  unspecified
+ * @queue_left: The queue (counter) this packet was applied to
  */
 struct batadv_forw_packet {
        struct hlist_node list;
@@ -1387,6 +1388,7 @@ struct batadv_forw_packet {
        struct delayed_work delayed_work;
        struct batadv_hard_iface *if_incoming;
        struct batadv_hard_iface *if_outgoing;
+       atomic_t *queue_left;
 };
 
 /**