[PATCH net-next v2 06/12] net-timestamp: introduce TS_SCHED_OPT_CB to generate dev xmit timestamp

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

Introduce BPF_SOCK_OPS_TS_SCHED_OPT_CB flag so that we can decide to
print timestamps when the skb just passes the dev layer.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 17 +++++++++++++++--
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 157e139ed6fc..3cf3c9c896c7 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7019,6 +7019,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
+					 * dev layer when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3a4110d0f983..16e7bdc1eacb 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5632,8 +5632,21 @@ static void bpf_skb_tstamp_tx_output(struct sock *sk, int tstype)
 		return;
 
 	tp = tcp_sk(sk);
-	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG))
-		return;
+	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG)) {
+		struct timespec64 tstamp;
+		u32 cb_flag;
+
+		switch (tstype) {
+		case SCM_TSTAMP_SCHED:
+			cb_flag = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
+			break;
+		default:
+			return;
+		}
+
+		tstamp = ktime_to_timespec64(ktime_get_real());
+		tcp_call_bpf_2arg(sk, cb_flag, tstamp.tv_sec, tstamp.tv_nsec);
+	}
 }
 
 void __skb_tstamp_tx(struct sk_buff *orig_skb,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 93853d9d4922..d60675e1a5a0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7018,6 +7018,11 @@ enum {
 					 * by the kernel or the
 					 * earlier bpf-progs.
 					 */
+	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
+					 * dev layer when SO_TIMESTAMPING
+					 * feature is on. It indicates the
+					 * recorded timestamp.
+					 */
 };
 
 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
-- 
2.37.3