summaryrefslogtreecommitdiff
path: root/net
diff options
context:
space:
mode:
authorDavid Morley <morleyd@google.com>2023-10-06 04:18:41 +0300
committerPaolo Abeni <pabeni@redhat.com>2023-10-10 11:02:59 +0300
commit939463016b7a869d8b407cfcda4d6545de399698 (patch)
tree1008b5a803e12d4077026e516d6f7a75ebfc244d /net
parent95b9a87c6a6b708cccda1f9b7baf9920b80cdabf (diff)
downloadlinux-939463016b7a869d8b407cfcda4d6545de399698.tar.xz
tcp: change data receiver flowlabel after one dup
This commit changes the data receiver repath behavior to occur after receiving a single duplicate. This can help recover ACK connectivity quicker if a TLP was sent along a nonworking path. For instance, consider the case where we have an initially nonworking forward path and reverse path and subsequently switch to only working forward paths. Before this patch we would have the following behavior. +---------+--------+--------+----------+----------+----------+ | Event | For FL | Rev FL | FP Works | RP Works | Data Del | +---------+--------+--------+----------+----------+----------+ | Initial | A | 1 | N | N | 0 | +---------+--------+--------+----------+----------+----------+ | TLP | A | 1 | N | N | 0 | +---------+--------+--------+----------+----------+----------+ | RTO 1 | B | 1 | Y | N | 1 | +---------+--------+--------+----------+----------+----------+ | RTO 2 | C | 1 | Y | N | 2 | +---------+--------+--------+----------+----------+----------+ | RTO 3 | D | 2 | Y | Y | 3 | +---------+--------+--------+----------+----------+----------+ This patch gets rid of at least RTO 3, avoiding additional unnecessary repaths of a working forward path to a (potentially) nonworking one. In addition, this commit changes the behavior to avoid repathing upon rx of duplicate data if the local endpoint is in CA_Loss (in which case the RTOs will already be changing the outgoing flowlabel). Signed-off-by: David Morley <morleyd@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Tested-by: David Morley <morleyd@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2ae4b211c125..ab87f0285b72 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4524,15 +4524,23 @@ static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb)
{
/* When the ACK path fails or drops most ACKs, the sender would
* timeout and spuriously retransmit the same segment repeatedly.
- * The receiver remembers and reflects via DSACKs. Leverage the
- * DSACK state and change the txhash to re-route speculatively.
+ * If it seems our ACKs are not reaching the other side,
+ * based on receiving a duplicate data segment with new flowlabel
+ * (suggesting the sender suffered an RTO), and we are not already
+ * repathing due to our own RTO, then rehash the socket to repath our
+ * packets.
*/
- if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq &&
+#if IS_ENABLED(CONFIG_IPV6)
+ if (inet_csk(sk)->icsk_ca_state != TCP_CA_Loss &&
+ skb->protocol == htons(ETH_P_IPV6) &&
+ (tcp_sk(sk)->inet_conn.icsk_ack.lrcv_flowlabel !=
+ ntohl(ip6_flowlabel(ipv6_hdr(skb)))) &&
sk_rethink_txhash(sk))
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
/* Save last flowlabel after a spurious retrans. */
tcp_save_lrcv_flowlabel(sk, skb);
+#endif
}
static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)