[5/6] batman-adv: restructure rebroadcast counter into forw_packet API
Commit Message
This patch refactors the num_packets counter of a forw_packet in the
following three ways:
1) Removed dual-use of forw_packet::num_packets:
-> now for aggregation purposes only
2) Using forw_packet::skb::cb::num_bcasts instead:
-> for easier access in aggregation code later
3) make access to num_bcasts private to batadv_forw_packet_*()
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
net/batman-adv/distributed-arp-table.c | 2 +-
net/batman-adv/main.c | 3 ++
net/batman-adv/send.c | 50 ++++++++++++++++++++++++++++++++--
net/batman-adv/send.h | 1 +
net/batman-adv/types.h | 4 ++-
5 files changed, 55 insertions(+), 5 deletions(-)
Comments
On Sonntag, 29. Januar 2017 14:57:42 CET Linus Lüssing wrote:
> This patch refactors the num_packets counter of a forw_packet in the
> following three ways:
>
> 1) Removed dual-use of forw_packet::num_packets:
> -> now for aggregation purposes only
> 2) Using forw_packet::skb::cb::num_bcasts instead:
> -> for easier access in aggregation code later
> 3) make access to num_bcasts private to batadv_forw_packet_*()
I like this change but have some questions (but no time to check it). Is cb
initialized when a new skbuff is allocated? And what about the initialization
for packets we get via batadv_interface_tx? At least batman-adv is only
setting it to zero when we receive a new packet from an hardif
(batadv_batman_skb_recv).
Kind regards,
Sven
On Mon, Feb 06, 2017 at 11:25:00AM +0100, Sven Eckelmann wrote:
> I like this change but have some questions (but no time to check it). Is cb
> initialized when a new skbuff is allocated?
Hm, good point. It looks like skb->cb is set to zero for newly
allocated skbs via a memset down to skb->tail. However, I could
not find anything resetting it to zero in net/core/dev.c, so there
could potentially be an issue.
It seems like network-coding.c might have the same issue already
for skb::cb::decoded.
@@ -1256,7 +1256,7 @@ bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
/* If this packet is an ARP_REQUEST and the node already has the
* information that it is going to ask, then the packet can be dropped
*/
- if (forw_packet->num_packets)
+ if (batadv_forw_packet_is_rebroadcast(forw_packet))
goto out;
vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
@@ -534,6 +534,9 @@ static void batadv_recv_handler_init(void)
BUILD_BUG_ON(sizeof(struct batadv_tvlv_tt_change) != 12);
BUILD_BUG_ON(sizeof(struct batadv_tvlv_roam_adv) != 8);
+ i = FIELD_SIZEOF(struct sk_buff, cb);
+ BUILD_BUG_ON(sizeof(struct batadv_skb_cb) > i);
+
/* broadcast packet */
batadv_rx_handler[BATADV_BCAST] = batadv_recv_bcast_packet;
@@ -798,6 +798,50 @@ err:
return NETDEV_TX_BUSY;
}
+/**
+ * batadv_forw_packet_bcasts_left - check if a retransmission is necessary
+ * @forw_packet: the forwarding packet to check
+ * @hard_iface: the interface to check on
+ *
+ * Checks whether a given packet has any (re)transmissions left on the provided
+ * interface.
+ *
+ * hard_iface may be NULL: In that case the number of transmissions this skb had
+ * so far is compared with the maximum amount of retransmissions independent of
+ * any interface instead.
+ *
+ * Return: True if (re)transmissions are left, false otherwise.
+ */
+static bool
+batadv_forw_packet_bcasts_left(struct batadv_forw_packet *forw_packet,
+ struct batadv_hard_iface *hard_iface)
+{
+ int max = hard_iface ? hard_iface->num_bcasts : BATADV_NUM_BCASTS_MAX;
+
+ return BATADV_SKB_CB(forw_packet->skb)->num_bcasts < max;
+}
+
+/**
+ * batadv_forw_packet_bcasts_inc - increment retransmission counter of a packet
+ * @forw_packet: the packet to increase the counter for
+ */
+static void
+batadv_forw_packet_bcasts_inc(struct batadv_forw_packet *forw_packet)
+{
+ BATADV_SKB_CB(forw_packet->skb)->num_bcasts++;
+}
+
+/**
+ * batadv_forw_packet_is_rebroadcast - check packet for previous transmissions
+ * @forw_packet: the packet to check
+ *
+ * Return: True if this packet was transmitted before, false otherwise.
+ */
+bool batadv_forw_packet_is_rebroadcast(struct batadv_forw_packet *forw_packet)
+{
+ return BATADV_SKB_CB(forw_packet->skb)->num_bcasts > 0;
+}
+
static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
{
struct batadv_hard_iface *hard_iface;
@@ -837,7 +881,7 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
if (hard_iface->soft_iface != soft_iface)
continue;
- if (forw_packet->num_packets >= hard_iface->num_bcasts)
+ if (!batadv_forw_packet_bcasts_left(forw_packet, hard_iface))
continue;
if (forw_packet->own) {
@@ -896,10 +940,10 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
}
rcu_read_unlock();
- forw_packet->num_packets++;
+ batadv_forw_packet_bcasts_inc(forw_packet);
/* if we still have some more bcasts to send */
- if (forw_packet->num_packets < BATADV_NUM_BCASTS_MAX) {
+ if (batadv_forw_packet_bcasts_left(forw_packet, NULL)) {
batadv_forw_packet_bcast_queue(bat_priv, forw_packet,
send_time);
return;
@@ -40,6 +40,7 @@ bool batadv_forw_packet_steal(struct batadv_forw_packet *packet, spinlock_t *l);
void batadv_forw_packet_ogmv1_queue(struct batadv_priv *bat_priv,
struct batadv_forw_packet *forw_packet,
unsigned long send_time);
+bool batadv_forw_packet_is_rebroadcast(struct batadv_forw_packet *forw_packet);
int batadv_send_skb_to_orig(struct sk_buff *skb,
struct batadv_orig_node *orig_node,
@@ -1444,9 +1444,11 @@ struct batadv_nc_packet {
* relevant to batman-adv in the skb->cb buffer in skbs.
* @decoded: Marks a skb as decoded, which is checked when searching for coding
* opportunities in network-coding.c
+ * @num_bcasts: Counter for broadcast packet retransmissions
*/
struct batadv_skb_cb {
bool decoded;
+ int num_bcasts;
};
/**
@@ -1459,7 +1461,7 @@ struct batadv_skb_cb {
* @skb: bcast packet's skb buffer
* @packet_len: size of aggregated OGM packet inside the skb buffer
* @direct_link_flags: direct link flags for aggregated OGM packets
- * @num_packets: counter for bcast packet retransmission
+ * @num_packets: counter for aggregated OGMv1 packets
* @delayed_work: work queue callback item for packet sending
* @if_incoming: pointer to incoming hard-iface or primary iface if
* locally generated packet