[RFC PATCH net-next v6 07/13] net-timestamp: support sw SCM_TSTAMP_SND for bpf extension

[Jason Xing <kerneljasonxing@gmail.com>]

Support SCM_TSTAMP_SND case. Then we will get the software
timestamp when the driver is about to send the skb. Later, I
will support the hardware timestamp.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
---
 include/linux/skbuff.h         |  2 +-
 include/uapi/linux/bpf.h       |  5 +++++
 net/core/skbuff.c              | 10 ++++++++--
 tools/include/uapi/linux/bpf.h |  5 +++++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 35c2e864dd4b..de8d3bd311f5 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4569,7 +4569,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
 static inline void skb_tx_timestamp(struct sk_buff *skb)
 {
 	skb_clone_tx_timestamp(skb);
-	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
+	if (skb_shinfo(skb)->tx_flags & (SKBTX_SW_TSTAMP | SKBTX_BPF))
 		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, true, SCM_TSTAMP_SND);
 }
 
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 72f93c6e45c1..a6d761f07f67 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7027,6 +7027,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_SW_OPT_CB,	/* Called when skb is about to send
+					 * to the nic 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 d19d577b996f..288eb9869827 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5564,7 +5564,8 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
 	return false;
 }
 
-static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk, int tstype)
+static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
+			      int tstype, bool sw)
 {
 	int op;
 
@@ -5575,6 +5576,11 @@ static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk, int tstype)
 	case SCM_TSTAMP_SCHED:
 		op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
 		break;
+	case SCM_TSTAMP_SND:
+		if (!sw)
+			return;
+		op = BPF_SOCK_OPS_TS_SW_OPT_CB;
+		break;
 	default:
 		return;
 	}
@@ -5596,7 +5602,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 
 	/* bpf extension feature entry */
 	if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
-		skb_tstamp_tx_bpf(orig_skb, sk, tstype);
+		skb_tstamp_tx_bpf(orig_skb, sk, tstype, sw);
 
 	/* application feature entry */
 	if (!skb_enable_app_tstamp(orig_skb, tstype, sw))
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 891217ab6d2d..73fc0a95c9ca 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7020,6 +7020,11 @@ enum {
 					 * feature is on. It indicates the
 					 * recorded timestamp.
 					 */
+	BPF_SOCK_OPS_TS_SW_OPT_CB,	/* Called when skb is about to send
+					 * to the nic 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
-- 
2.43.5