tcp: add dsack blocks received stats

Introduce a new TCP stat to record the number of DSACK blocks received
(RFC4989 tcpEStatsStackDSACKDups) and expose it in both tcp_info
(TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS).

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index c31f5100b744..0e1c0aec0153 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -238,6 +238,7 @@ struct tcp_info {
 
         __u64   tcpi_bytes_sent;     /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
         __u64   tcpi_bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans */
+        __u32   tcpi_dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups */
 };
 
 /* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
@@ -262,6 +263,7 @@ enum {
         TCP_NLA_DELIVERED_CE,   /* Like above but only ones w/ CE marks */
         TCP_NLA_BYTES_SENT,     /* Data bytes sent including retransmission */
         TCP_NLA_BYTES_RETRANS,  /* Data bytes retransmitted */
+        TCP_NLA_DSACK_DUPS,     /* DSACK blocks received */
 };
 
 /* for TCP_MD5SIG socket option */