net-timestamp: ACK timestamp for bytestreams
Add SOF_TIMESTAMPING_TX_ACK, a request for a tstamp when the last byte
in the send() call is acknowledged. It implements the feature for TCP.
The timestamp is generated when the TCP socket cumulative ACK is moved
beyond the tracked seqno for the first time. The feature ignores SACK
and FACK, because those acknowledge the specific byte, but not
necessarily the entire contents of the buffer up to that byte.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6a29845..a3d47af 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -74,6 +74,7 @@
#include <linux/ipsec.h>
#include <asm/unaligned.h>
#include <net/netdma.h>
+#include <linux/errqueue.h>
int sysctl_tcp_timestamps __read_mostly = 1;
int sysctl_tcp_window_scaling __read_mostly = 1;
@@ -3106,6 +3107,11 @@
tp->retrans_stamp = 0;
}
+ if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_ACK_TSTAMP) &&
+ between(skb_shinfo(skb)->tskey, prior_snd_una,
+ tp->snd_una + 1))
+ __skb_tstamp_tx(skb, NULL, sk, SCM_TSTAMP_ACK);
+
if (!fully_acked)
break;
diff --git a/net/socket.c b/net/socket.c
index 3a2778d..ae89569 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -619,6 +619,8 @@
*tx_flags |= SKBTX_SW_TSTAMP;
if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED)
*tx_flags |= SKBTX_SCHED_TSTAMP;
+ if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK)
+ *tx_flags |= SKBTX_ACK_TSTAMP;
if (sock_flag(sk, SOCK_WIFI_STATUS))
*tx_flags |= SKBTX_WIFI_STATUS;
