commit 62271c5c0b08041b24930310c04e3933720917c6
Author: Fabio M. Di Nitto <fdinitto@redhat.com>
Date:   Mon Nov 8 09:14:22 2021 +0100

    [host] fix dst_seq_num initialization race condition
    
    There is a potential race condition where the sender
    is overloaded, sending data packets before pings
    can kick in and set the correct dst_seq_num.
    
    if this node is starting up (dst_seq_num = 0),
    it can start rejecing valid packets and get stuck.
    
    Set the dst_seq_num to the first seen packet and
    use that as reference instead.
    
    Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

diff --git a/libknet/host.c b/libknet/host.c
index f02ef02..54061fd 100644
--- a/libknet/host.c
+++ b/libknet/host.c
@@ -617,6 +617,21 @@ int _seq_num_lookup(knet_handle_t knet_h, struct knet_host *host, seq_num_t seq_
 	char *dst_cbuf_defrag = host->circular_buffer_defrag;
 	seq_num_t *dst_seq_num = &host->rx_seq_num;
 
+	/*
+	 * There is a potential race condition where the sender
+	 * is overloaded, sending data packets before pings
+	 * can kick in and set the correct dst_seq_num.
+	 *
+	 * if this node is starting up (dst_seq_num = 0),
+	 * it can start rejecing valid packets and get stuck.
+	 *
+	 * Set the dst_seq_num to the first seen packet and
+	 * use that as reference instead.
+	 */
+	if (!*dst_seq_num) {
+		*dst_seq_num = seq_num;
+	}
+
 	if (clear_buf) {
 		_clear_cbuffers(host, seq_num);
 	}