[PATCH net-next v5 06/15] net-timestamp: prepare for isolating two modes of SO_TIMESTAMPING

[Jason Xing <kerneljasonxing@gmail.com>]

No functional changes here. I add skb_enable_app_tstamp() to test
if the orig_skb matches the usage of application SO_TIMESTAMPING
and skb_sw_tstamp_tx() to distinguish the software and hardware
timestamp when tsflag is SCM_TSTAMP_SND.

After this patch, I will soon add checks about bpf SO_TIMESTAMPING.
In this way, we can support two modes parallelly.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
---
 include/linux/skbuff.h | 22 ++++++++++++++++------
 net/core/dev.c         |  2 +-
 net/core/skbuff.c      | 42 ++++++++++++++++++++++++++++++++++++++++--
 net/ipv4/tcp_input.c   |  3 ++-
 4 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb2b751d274a..09461ee84d2f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4533,21 +4533,31 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
 
 void __skb_tstamp_tx(struct sk_buff *orig_skb, const struct sk_buff *ack_skb,
 		     struct skb_shared_hwtstamps *hwtstamps,
-		     struct sock *sk, int tstype);
+		     struct sock *sk, bool sw, int tstype);
 
 /**
- * skb_tstamp_tx - queue clone of skb with send time stamps
+ * skb_tstamp_tx - queue clone of skb with send time HARDWARE stamps
  * @orig_skb:	the original outgoing packet
  * @hwtstamps:	hardware time stamps, may be NULL if not available
  *
  * If the skb has a socket associated, then this function clones the
  * skb (thus sharing the actual data and optional structures), stores
- * the optional hardware time stamping information (if non NULL) or
- * generates a software time stamp (otherwise), then queues the clone
- * to the error queue of the socket.  Errors are silently ignored.
+ * the optional hardware time stamping information (if non NULL) then
+ * queues the clone to the error queue of the socket.  Errors are
+ * silently ignored.
  */
 void skb_tstamp_tx(struct sk_buff *orig_skb,
 		   struct skb_shared_hwtstamps *hwtstamps);
+/**
+ * skb_tstamp_tx - queue clone of skb with send time SOFTWARE stamps
+ * @orig_skb:	the original outgoing packet
+ *
+ * If the skb has a socket associated, then this function clones the
+ * skb (thus sharing the actual data and optional structures),
+ * generates a software time stamp (otherwise), then queues the clone
+ * to the error queue of the socket.  Errors are silently ignored.
+ */
+void skb_sw_tstamp_tx(struct sk_buff *orig_skb);
 
 /**
  * skb_tx_timestamp() - Driver hook for transmit timestamping
@@ -4565,7 +4575,7 @@ static inline void skb_tx_timestamp(struct sk_buff *skb)
 {
 	skb_clone_tx_timestamp(skb);
 	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
-		skb_tstamp_tx(skb, NULL);
+		skb_sw_tstamp_tx(skb);
 }
 
 /**
diff --git a/net/core/dev.c b/net/core/dev.c
index 1a90ed8cc6cc..397fbcd5e4de 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4398,7 +4398,7 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
 	skb_assert_len(skb);
 
 	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
-		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
+		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, true, SCM_TSTAMP_SCHED);
 
 	/* Disable soft irqs for various locks below. Also
 	 * stops preemption for RCU.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a441613a1e6c..b34c7ec3d5e9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5539,10 +5539,38 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
 }
 EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
 
+static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
+{
+	int flag;
+
+	switch (tstype) {
+	case SCM_TSTAMP_SCHED:
+		flag = SKBTX_SCHED_TSTAMP;
+		break;
+	case SCM_TSTAMP_SND:
+		if (sw)
+			flag = SKBTX_SW_TSTAMP;
+		else
+			flag = SKBTX_HW_TSTAMP;
+		break;
+	case SCM_TSTAMP_ACK:
+		if (TCP_SKB_CB(skb)->txstamp_ack)
+			return true;
+		fallthrough;
+	default:
+		return false;
+	}
+
+	if (skb_shinfo(skb)->tx_flags & flag)
+		return true;
+
+	return false;
+}
+
 void __skb_tstamp_tx(struct sk_buff *orig_skb,
 		     const struct sk_buff *ack_skb,
 		     struct skb_shared_hwtstamps *hwtstamps,
-		     struct sock *sk, int tstype)
+		     struct sock *sk, bool sw, int tstype)
 {
 	struct sk_buff *skb;
 	bool tsonly, opt_stats = false;
@@ -5551,6 +5579,9 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 	if (!sk)
 		return;
 
+	if (!skb_enable_app_tstamp(orig_skb, tstype, sw))
+		return;
+
 	tsflags = READ_ONCE(sk->sk_tsflags);
 	if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
 	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
@@ -5596,10 +5627,17 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
 }
 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
 
+void skb_sw_tstamp_tx(struct sk_buff *orig_skb)
+{
+	return __skb_tstamp_tx(orig_skb, NULL, NULL, orig_skb->sk, true,
+			       SCM_TSTAMP_SND);
+}
+EXPORT_SYMBOL_GPL(skb_sw_tstamp_tx);
+
 void skb_tstamp_tx(struct sk_buff *orig_skb,
 		   struct skb_shared_hwtstamps *hwtstamps)
 {
-	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
+	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk, false,
 			       SCM_TSTAMP_SND);
 }
 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index cad41ad34bd5..c2cdd0acb504 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3330,7 +3330,8 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
 	if (!before(shinfo->tskey, prior_snd_una) &&
 	    before(shinfo->tskey, tcp_sk(sk)->snd_una)) {
 		tcp_skb_tsorted_save(skb) {
-			__skb_tstamp_tx(skb, ack_skb, NULL, sk, SCM_TSTAMP_ACK);
+			__skb_tstamp_tx(skb, ack_skb, NULL, sk, true,
+					SCM_TSTAMP_ACK);
 		} tcp_skb_tsorted_restore(skb);
 	}
 }
-- 
2.43.5