Subject: [PATCH net-next 2/9] net-timestamp: introduce TS_SCHED_OPT_CB to generate dev xmit timestamp

From: Jason Xing <[email-masked]>
Date: Tue, 8 Oct 2024 17:51:02 +0800

From: Jason Xing <[email-masked]>

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 <[email-masked]>
---
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 16 +++++++++++++++-
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 25 insertions(+), 1 deletion(-)

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 5ff1a91c1204..e697f50d1182 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5548,8 +5548,22 @@ static bool bpf_skb_tstamp_tx(struct sock *sk, u32 scm_flag,
 		return false;
 
 	tp = tcp_sk(sk);
-	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG))
+	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_TX_TIMESTAMPING_OPT_CB_FLAG)) {
+		struct timespec64 tstamp;
+		u32 cb_flag;
+
+		switch (scm_flag) {
+		case SCM_TSTAMP_SCHED:
+			cb_flag = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
+			break;
+		default:
+			return true;
+		}
+
+		tstamp = ktime_to_timespec64(ktime_get_real());
+		tcp_call_bpf_2arg(sk, cb_flag, tstamp.tv_sec, tstamp.tv_nsec);
 		return true;
+	}
 
 	return false;
 }
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