5 files changed, 17 insertions, 2 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 50e1e9b3a5a5..11c270551d25 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -250,9 +250,14 @@ enum {
 
         /* generate software time stamp when entering packet scheduling */
         SKBTX_SCHED_TSTAMP = 1 << 6,
+
+        /* generate software timestamp on peer data acknowledgment */
+        SKBTX_ACK_TSTAMP = 1 << 7,
 };
 
-#define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP | SKBTX_SCHED_TSTAMP)
+#define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
+                                 SKBTX_SCHED_TSTAMP | \
+                                 SKBTX_ACK_TSTAMP)
 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
 
 /*
diff --git a/include/uapi/linux/errqueue.h b/include/uapi/linux/errqueue.h
index 17437cf297b7..07bdce1f444a 100644
--- a/include/uapi/linux/errqueue.h
+++ b/include/uapi/linux/errqueue.h
@@ -40,6 +40,7 @@ struct scm_timestamping {
 enum {
         SCM_TSTAMP_SND,         /* driver passed skb to NIC, or HW */
         SCM_TSTAMP_SCHED,       /* data entered the packet scheduler */
+        SCM_TSTAMP_ACK,         /* data acknowledged by peer */
 };
 
 #endif /* _UAPI_LINUX_ERRQUEUE_H */
diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
index 60733845fcdd..ff354021bb69 100644
--- a/include/uapi/linux/net_tstamp.h
+++ b/include/uapi/linux/net_tstamp.h
@@ -22,8 +22,9 @@ enum {
         SOF_TIMESTAMPING_RAW_HARDWARE = (1<<6),
         SOF_TIMESTAMPING_OPT_ID = (1<<7),
         SOF_TIMESTAMPING_TX_SCHED = (1<<8),
+        SOF_TIMESTAMPING_TX_ACK = (1<<9),
 
-        SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_TX_SCHED,
+        SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_TX_ACK,
         SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |
                                  SOF_TIMESTAMPING_LAST
 };
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6a2984507755..a3d47af01906 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 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
                         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 3a2778d71631..ae89569a2db5 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -619,6 +619,8 @@ void sock_tx_timestamp(struct sock *sk, __u8 *tx_flags)
                 *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;