Subject: [RFC PATCH net-next v6 10/13] net-timestamp: make TCP tx timestamp bpf extension work

From: Jason Xing <[email-masked]>
Date: Tue, 21 Jan 2025 09:28:58 +0800

Make partial of the feature work finally. After this, user can
fully use the bpf prog to trace the tx path for TCP type.

Signed-off-by: Jason Xing <[email-masked]>
---
 net/ipv4/tcp.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0d704bda6c41..0a41006b10d1 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -492,6 +492,15 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
 		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
 			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
 	}
+
+	if (SK_BPF_CB_FLAG_TEST(sk, SK_BPF_CB_TX_TIMESTAMPING) && skb) {
+		struct skb_shared_info *shinfo = skb_shinfo(skb);
+		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+		tcb->txstamp_ack_bpf = 1;
+		shinfo->tx_flags |= SKBTX_BPF;
+		shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+	}
 }
 
 static bool tcp_stream_is_readable(struct sock *sk, int target)
-- 
2.43.5