Commit e7ed11ee authored by Yousuk Seung's avatar Yousuk Seung Committed by Jakub Kicinski
Browse files

tcp: add TTL to SCM_TIMESTAMPING_OPT_STATS 



This patch adds TCP_NLA_TTL to SCM_TIMESTAMPING_OPT_STATS that exports
the time-to-live or hop limit of the latest incoming packet with
SCM_TSTAMP_ACK. The value exported may not be from the packet that acks
the sequence when incoming packets are aggregated. Exporting the
time-to-live or hop limit value of incoming packets helps to estimate
the hop count of the path of the flow that may change over time.

Signed-off-by: default avatarYousuk Seung <ysseung@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20210120204155.552275-1-ysseung@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent a05a7280

include/linux/skbuff.h

+1 −1
Original line number Diff line number Diff line
@@ -3859,7 +3859,7 @@ static inline bool skb_defer_rx_timestamp(struct sk_buff *skb) 
void skb_complete_tx_timestamp(struct sk_buff *skb,

			       struct skb_shared_hwtstamps *hwtstamps);



void __skb_tstamp_tx(struct sk_buff *orig_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);

include/linux/tcp.h

+2 −1
Original line number Diff line number Diff line
@@ -496,7 +496,8 @@ static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn) 
}



struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,

					       const struct sk_buff *orig_skb);

					       const struct sk_buff *orig_skb,

					       const struct sk_buff *ack_skb);



static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)

{

include/uapi/linux/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -314,6 +314,7 @@ enum { 
	TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */

	TCP_NLA_BYTES_NOTSENT,	/* Bytes in write queue not yet sent */

	TCP_NLA_EDT,		/* Earliest departure time (CLOCK_MONOTONIC) */

	TCP_NLA_TTL,		/* TTL or hop limit of a packet received */

};



/* for TCP_MD5SIG socket option */

net/core/dev.c

+1 −1
Original line number Diff line number Diff line
@@ -4084,7 +4084,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) 
	skb_reset_mac_header(skb);



	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))

		__skb_tstamp_tx(skb, NULL, skb->sk, SCM_TSTAMP_SCHED);

		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);



	/* Disable soft irqs for various locks below. Also

	 * stops preemption for RCU.

net/core/skbuff.c

+4 −2
Original line number Diff line number Diff line
@@ -4721,6 +4721,7 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, 
EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);



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)

{
@@ -4743,7 +4744,8 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, 
		if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&

		    sk->sk_protocol == IPPROTO_TCP &&

		    sk->sk_type == SOCK_STREAM) {

			skb = tcp_get_timestamping_opt_stats(sk, orig_skb);

			skb = tcp_get_timestamping_opt_stats(sk, orig_skb,

							     ack_skb);

			opt_stats = true;

		} else

#endif
@@ -4772,7 +4774,7 @@ EXPORT_SYMBOL_GPL(__skb_tstamp_tx); 
void skb_tstamp_tx(struct sk_buff *orig_skb,

		   struct skb_shared_hwtstamps *hwtstamps)

{

	return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk,

	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,

			       SCM_TSTAMP_SND);

}

EXPORT_SYMBOL_GPL(skb_tstamp_tx);