tipc: rate limit broadcast retransmissions

[cascardo/linux.git] / net / tipc / link.c

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 136316f..58bb44d 100644 (file)
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -181,7 +181,10 @@ struct tipc_link {
        u16 acked;
        struct tipc_link *bc_rcvlink;
        struct tipc_link *bc_sndlink;
-       int nack_state;
+       unsigned long prev_retr;
+       u16 prev_from;
+       u16 prev_to;
+       u8 nack_state;
        bool bc_peer_is_up;
 
        /* Statistics */
@@ -202,6 +205,8 @@ enum {
        BC_NACK_SND_SUPPRESS,
 };
 
+#define TIPC_BC_RETR_LIMIT 10   /* [ms] */
+
 /*
  * Interval between NACKs when packets arrive out of order
  */
@@ -1590,11 +1595,48 @@ void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
                l->rcv_nxt = peers_snd_nxt;
 }
 
+/* link_bc_retr eval()- check if the indicated range can be retransmitted now
+ * - Adjust permitted range if there is overlap with previous retransmission
+ */
+static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
+{
+       unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);
+
+       if (less(*to, *from))
+               return false;
+
+       /* New retransmission request */
+       if ((elapsed > TIPC_BC_RETR_LIMIT) ||
+           less(*to, l->prev_from) || more(*from, l->prev_to)) {
+               l->prev_from = *from;
+               l->prev_to = *to;
+               l->prev_retr = jiffies;
+               return true;
+       }
+
+       /* Inside range of previous retransmit */
+       if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
+               return false;
+
+       /* Fully or partially outside previous range => exclude overlap */
+       if (less(*from, l->prev_from)) {
+               *to = l->prev_from - 1;
+               l->prev_from = *from;
+       }
+       if (more(*to, l->prev_to)) {
+               *from = l->prev_to + 1;
+               l->prev_to = *to;
+       }
+       l->prev_retr = jiffies;
+       return true;
+}
+
 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
  */
 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
                          struct sk_buff_head *xmitq)
 {
+       struct tipc_link *snd_l = l->bc_sndlink;
        u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
        u16 from = msg_bcast_ack(hdr) + 1;
        u16 to = from + msg_bc_gap(hdr) - 1;
@@ -1613,14 +1655,14 @@ int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
        if (!l->bc_peer_is_up)
                return rc;
 
+       l->stats.recv_nacks++;
+
        /* Ignore if peers_snd_nxt goes beyond receive window */
        if (more(peers_snd_nxt, l->rcv_nxt + l->window))
                return rc;
 
-       if (!less(to, from)) {
-               rc = tipc_link_retrans(l->bc_sndlink, from, to, xmitq);
-               l->stats.recv_nacks++;
-       }
+       if (link_bc_retr_eval(snd_l, &from, &to))
+               rc = tipc_link_retrans(snd_l, from, to, xmitq);
 
        l->snd_nxt = peers_snd_nxt;
        if (link_bc_rcv_gap(l))