@@ -3996,6 +3996,22 @@ static inline void skb_set_delivery_time(struct sk_buff *skb, ktime_t kt,
skb->mono_delivery_time = 0;
}
+DECLARE_STATIC_KEY_FALSE(netstamp_needed_key);
+
+/* It is used in the ingress path to clear the delivery_time.
+ * If needed, set the skb->tstamp to the (rcv) timestamp.
+ */
+static inline void skb_clear_delivery_time(struct sk_buff *skb)
+{
+ if (skb->mono_delivery_time) {
+ skb->mono_delivery_time = 0;
+ if (static_branch_unlikely(&netstamp_needed_key))
+ skb->tstamp = ktime_get_real();
+ else
+ skb->tstamp = 0;
+ }
+}
+
static inline void skb_clear_tstamp(struct sk_buff *skb)
{
if (skb->mono_delivery_time)
@@ -4004,6 +4020,14 @@ static inline void skb_clear_tstamp(struct sk_buff *skb)
skb->tstamp = 0;
}
+static inline ktime_t skb_tstamp(const struct sk_buff *skb)
+{
+ if (skb->mono_delivery_time)
+ return 0;
+
+ return skb->tstamp;
+}
+
static inline u8 skb_metadata_len(const struct sk_buff *skb)
{
return skb_shinfo(skb)->meta_len;
@@ -2020,7 +2020,8 @@ void net_dec_egress_queue(void)
EXPORT_SYMBOL_GPL(net_dec_egress_queue);
#endif
-static DEFINE_STATIC_KEY_FALSE(netstamp_needed_key);
+DEFINE_STATIC_KEY_FALSE(netstamp_needed_key);
+EXPORT_SYMBOL(netstamp_needed_key);
#ifdef CONFIG_JUMP_LABEL
static atomic_t netstamp_needed_deferred;
static atomic_t netstamp_wanted;
@@ -2081,6 +2082,7 @@ EXPORT_SYMBOL(net_disable_timestamp);
static inline void net_timestamp_set(struct sk_buff *skb)
{
skb->tstamp = 0;
+ skb->mono_delivery_time = 0;
if (static_branch_unlikely(&netstamp_needed_key))
__net_timestamp(skb);
}
@@ -460,7 +460,7 @@ static __u32 tpacket_get_timestamp(struct sk_buff *skb, struct timespec64 *ts,
return TP_STATUS_TS_RAW_HARDWARE;
if ((flags & SOF_TIMESTAMPING_SOFTWARE) &&
- ktime_to_timespec64_cond(skb->tstamp, ts))
+ ktime_to_timespec64_cond(skb_tstamp(skb), ts))
return TP_STATUS_TS_SOFTWARE;
return 0;
@@ -2199,6 +2199,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
spin_lock(&sk->sk_receive_queue.lock);
po->stats.stats1.tp_packets++;
sock_skb_set_dropcount(sk, skb);
+ skb_clear_delivery_time(skb);
__skb_queue_tail(&sk->sk_receive_queue, skb);
spin_unlock(&sk->sk_receive_queue.lock);
sk->sk_data_ready(sk);
@@ -2377,6 +2378,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
po->stats.stats1.tp_packets++;
if (copy_skb) {
status |= TP_STATUS_COPY;
+ skb_clear_delivery_time(copy_skb);
__skb_queue_tail(&sk->sk_receive_queue, copy_skb);
}
spin_unlock(&sk->sk_receive_queue.lock);
A latter patch will set the skb->mono_delivery_time to flag the skb->tstamp is used as the mono delivery_time (EDT) instead of the (rcv) timestamp. skb_clear_tstamp() will then keep this delivery_time during forwarding. This patch is to make the network tapping (with af_packet) to handle the delivery_time stored in skb->tstamp. Regardless of tapping at the ingress or egress, the tapped skb is received by the af_packet socket, so it is ingress to the af_packet socket and it expects the (rcv) timestamp. When tapping at egress, dev_queue_xmit_nit() is used. It has already expected skb->tstamp may have delivery_time, so it does skb_clone()+net_timestamp_set() to ensure the cloned skb has the (rcv) timestamp before passing to the af_packet sk. This patch only adds to clear the skb->mono_delivery_time bit in net_timestamp_set(). When tapping at ingress, it currently expects the skb->tstamp is either 0 or the (rcv) timestamp. Meaning, the tapping at ingress path has already expected the skb->tstamp could be 0 and it will get the (rcv) timestamp by ktime_get_real() when needed. There are two cases for tapping at ingress: One case is af_packet queues the skb to its sk_receive_queue. The skb is either not shared or new clone created. The newly added skb_clear_delivery_time() is called to clear the delivery_time (if any) and set the (rcv) timestamp if needed before the skb is queued to the sk_receive_queue. Another case, the ingress skb is directly copied to the rx_ring and tpacket_get_timestamp() is used to get the (rcv) timestamp. The newly added skb_tstamp() is used in tpacket_get_timestamp() to check the skb->mono_delivery_time bit before returning skb->tstamp. As mentioned earlier, the tapping@ingress has already expected the skb may not have the (rcv) timestamp (because no sk has asked for it) and has handled this case by directly calling ktime_get_real(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> --- include/linux/skbuff.h | 24 ++++++++++++++++++++++++ net/core/dev.c | 4 +++- net/packet/af_packet.c | 4 +++- 3 files changed, 30 insertions(+), 2 deletions(-)