[PATCH net-next v4 10/11] net-timestamp: export the tskey for TCP bpf extension

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

For now, there are three phases where we are not able to fetch
the right seqno from the skops->skb_data, because:
1) in __dev_queue_xmit(), the skb->data doesn't point to the start
offset in tcp header.
2) in tcp_ack_tstamp(), the skb doesn't have the tcp header.

In the long run, we may add other trace points for bpf extension.
And the shinfo->tskey is always the same value for both bpf and
non-bpf cases. With that said, let's directly use shinfo->tskey
for TCP protocol.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/core/skbuff.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7c59ef501c74..2e13643f791c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5544,7 +5544,7 @@ static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb,
 				int tstype)
 {
 	struct timespec64 tstamp;
-	u32 args[2] = {0, 0};
+	u32 args[3] = {0, 0, 0};
 	int op;
 
 	if (!sk)
@@ -5569,7 +5569,10 @@ static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb,
 		return;
 	}
 
-	bpf_skops_tx_timestamping(sk, skb, op, 2, args);
+	if (sk_is_tcp(sk))
+		args[2] = skb_shinfo(skb)->tskey;
+
+	bpf_skops_tx_timestamping(sk, skb, op, 3, args);
 }
 
 static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
-- 
2.37.3