Commit 98aaa913 authored by Mike Maloney's avatar Mike Maloney Committed by David S. Miller
Browse files

tcp: Extend SOF_TIMESTAMPING_RX_SOFTWARE to TCP recvmsg 



When SOF_TIMESTAMPING_RX_SOFTWARE is enabled for tcp sockets, return the
timestamp corresponding to the highest sequence number data returned.

Previously the skb->tstamp is overwritten when a TCP packet is placed
in the out of order queue.  While the packet is in the ooo queue, save the
timestamp in the TCB_SKB_CB.  This space is shared with the gso_*
options which are only used on the tx path, and a previously unused 4
byte hole.

When skbs are coalesced either in the sk_receive_queue or the
out_of_order_queue always choose the timestamp of the appended skb to
maintain the invariant of returning the timestamp of the last byte in
the recvmsg buffer.

Signed-off-by: default avatarMike Maloney <maloney@google.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b2854772

include/net/tcp.h

+8 −1
Original line number Diff line number Diff line
@@ -774,6 +774,12 @@ struct tcp_skb_cb { 
			u16	tcp_gso_segs;

			u16	tcp_gso_size;

		};



		/* Used to stash the receive timestamp while this skb is in the

		 * out of order queue, as skb->tstamp is overwritten by the

		 * rbnode.

		 */

		ktime_t		swtstamp;

	};

	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
@@ -790,7 +796,8 @@ struct tcp_skb_cb { 
	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/

	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */

			eor:1,		/* Is skb MSG_EOR marked? */

			unused:6;

			has_rxtstamp:1,	/* SKB has a RX timestamp	*/

			unused:5;

	__u32		ack_seq;	/* Sequence number ACK'd	*/

	union {

		struct {

net/ipv4/tcp.c

+65 −0
Original line number Diff line number Diff line
@@ -269,6 +269,7 @@ 
#include <linux/err.h>

#include <linux/time.h>

#include <linux/slab.h>

#include <linux/errqueue.h>



#include <net/icmp.h>

#include <net/inet_common.h>
@@ -1695,6 +1696,61 @@ int tcp_peek_len(struct socket *sock) 
}

EXPORT_SYMBOL(tcp_peek_len);



static void tcp_update_recv_tstamps(struct sk_buff *skb,

				    struct scm_timestamping *tss)

{

	if (skb->tstamp)

		tss->ts[0] = ktime_to_timespec(skb->tstamp);

	else

		tss->ts[0] = (struct timespec) {0};



	if (skb_hwtstamps(skb)->hwtstamp)

		tss->ts[2] = ktime_to_timespec(skb_hwtstamps(skb)->hwtstamp);

	else

		tss->ts[2] = (struct timespec) {0};

}



/* Similar to __sock_recv_timestamp, but does not require an skb */

void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,

			struct scm_timestamping *tss)

{

	struct timeval tv;

	bool has_timestamping = false;



	if (tss->ts[0].tv_sec || tss->ts[0].tv_nsec) {

		if (sock_flag(sk, SOCK_RCVTSTAMP)) {

			if (sock_flag(sk, SOCK_RCVTSTAMPNS)) {

				put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPNS,

					 sizeof(tss->ts[0]), &tss->ts[0]);

			} else {

				tv.tv_sec = tss->ts[0].tv_sec;

				tv.tv_usec = tss->ts[0].tv_nsec / 1000;



				put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMP,

					 sizeof(tv), &tv);

			}

		}



		if (sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE)

			has_timestamping = true;

		else

			tss->ts[0] = (struct timespec) {0};

	}



	if (tss->ts[2].tv_sec || tss->ts[2].tv_nsec) {

		if (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE)

			has_timestamping = true;

		else

			tss->ts[2] = (struct timespec) {0};

	}



	if (has_timestamping) {

		tss->ts[1] = (struct timespec) {0};

		put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING,

			 sizeof(*tss), tss);

	}

}



/*

 *	This routine copies from a sock struct into the user buffer.

 *
@@ -1716,6 +1772,8 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 
	long timeo;

	struct sk_buff *skb, *last;

	u32 urg_hole = 0;

	struct scm_timestamping tss;

	bool has_tss = false;



	if (unlikely(flags & MSG_ERRQUEUE))

		return inet_recv_error(sk, msg, len, addr_len);
@@ -1911,6 +1969,10 @@ skip_copy: 
		if (used + offset < skb->len)

			continue;



		if (TCP_SKB_CB(skb)->has_rxtstamp) {

			tcp_update_recv_tstamps(skb, &tss);

			has_tss = true;

		}

		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)

			goto found_fin_ok;

		if (!(flags & MSG_PEEK))
@@ -1929,6 +1991,9 @@ skip_copy: 
	 * on connected socket. I was just happy when found this 8) --ANK

	 */



	if (has_tss)

		tcp_recv_timestamp(msg, sk, &tss);



	/* Clean up data we have read: This will do ACK frames. */

	tcp_cleanup_rbuf(sk, copied);

net/ipv4/tcp_input.c

+31 −4
Original line number Diff line number Diff line
@@ -4246,9 +4246,15 @@ static void tcp_sack_remove(struct tcp_sock *tp) 
	tp->rx_opt.num_sacks = num_sacks;

}



enum tcp_queue {

	OOO_QUEUE,

	RCV_QUEUE,

};



/**

 * tcp_try_coalesce - try to merge skb to prior one

 * @sk: socket

 * @dest: destination queue

 * @to: prior buffer

 * @from: buffer to add in queue

 * @fragstolen: pointer to boolean
@@ -4260,6 +4266,7 @@ static void tcp_sack_remove(struct tcp_sock *tp) 
 * Returns true if caller should free @from instead of queueing it

 */

static bool tcp_try_coalesce(struct sock *sk,

			     enum tcp_queue dest,

			     struct sk_buff *to,

			     struct sk_buff *from,

			     bool *fragstolen)
@@ -4281,6 +4288,15 @@ static bool tcp_try_coalesce(struct sock *sk, 
	TCP_SKB_CB(to)->end_seq = TCP_SKB_CB(from)->end_seq;

	TCP_SKB_CB(to)->ack_seq = TCP_SKB_CB(from)->ack_seq;

	TCP_SKB_CB(to)->tcp_flags |= TCP_SKB_CB(from)->tcp_flags;



	if (TCP_SKB_CB(from)->has_rxtstamp) {

		TCP_SKB_CB(to)->has_rxtstamp = true;

		if (dest == OOO_QUEUE)

			TCP_SKB_CB(to)->swtstamp = TCP_SKB_CB(from)->swtstamp;

		else

			to->tstamp = from->tstamp;

	}



	return true;

}
@@ -4315,6 +4331,9 @@ static void tcp_ofo_queue(struct sock *sk) 
		}

		p = rb_next(p);

		rb_erase(&skb->rbnode, &tp->out_of_order_queue);

		/* Replace tstamp which was stomped by rbnode */

		if (TCP_SKB_CB(skb)->has_rxtstamp)

			skb->tstamp = TCP_SKB_CB(skb)->swtstamp;



		if (unlikely(!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt))) {

			SOCK_DEBUG(sk, "ofo packet was already received\n");
@@ -4326,7 +4345,8 @@ static void tcp_ofo_queue(struct sock *sk) 
			   TCP_SKB_CB(skb)->end_seq);



		tail = skb_peek_tail(&sk->sk_receive_queue);

		eaten = tail && tcp_try_coalesce(sk, tail, skb, &fragstolen);

		eaten = tail && tcp_try_coalesce(sk, RCV_QUEUE,

						 tail, skb, &fragstolen);

		tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);

		fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;

		if (!eaten)
@@ -4380,6 +4400,10 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) 
		return;

	}



	/* Stash tstamp to avoid being stomped on by rbnode */

	if (TCP_SKB_CB(skb)->has_rxtstamp)

		TCP_SKB_CB(skb)->swtstamp = skb->tstamp;



	inet_csk_schedule_ack(sk);



	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOQUEUE);
@@ -4405,7 +4429,8 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) 
	/* In the typical case, we are adding an skb to the end of the list.

	 * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.

	 */

	if (tcp_try_coalesce(sk, tp->ooo_last_skb, skb, &fragstolen)) {

	if (tcp_try_coalesce(sk, OOO_QUEUE, tp->ooo_last_skb,

			     skb, &fragstolen)) {

coalesce_done:

		tcp_grow_window(sk, skb);

		kfree_skb_partial(skb, fragstolen);
@@ -4455,7 +4480,8 @@ coalesce_done: 
				__kfree_skb(skb1);

				goto merge_right;

			}

		} else if (tcp_try_coalesce(sk, skb1, skb, &fragstolen)) {

		} else if (tcp_try_coalesce(sk, OOO_QUEUE, skb1,

					    skb, &fragstolen)) {

			goto coalesce_done;

		}

		p = &parent->rb_right;
@@ -4506,7 +4532,8 @@ static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int 


	__skb_pull(skb, hdrlen);

	eaten = (tail &&

		 tcp_try_coalesce(sk, tail, skb, fragstolen)) ? 1 : 0;

		 tcp_try_coalesce(sk, RCV_QUEUE, tail,

				  skb, fragstolen)) ? 1 : 0;

	tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);

	if (!eaten) {

		__skb_queue_tail(&sk->sk_receive_queue, skb);

net/ipv4/tcp_ipv4.c

+2 −0
Original line number Diff line number Diff line
@@ -1637,6 +1637,8 @@ int tcp_v4_rcv(struct sk_buff *skb) 
	TCP_SKB_CB(skb)->tcp_tw_isn = 0;

	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);

	TCP_SKB_CB(skb)->sacked	 = 0;

	TCP_SKB_CB(skb)->has_rxtstamp =

			skb->tstamp || skb_hwtstamps(skb)->hwtstamp;



lookup:

	sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source,

net/ipv6/tcp_ipv6.c

+2 −0
Original line number Diff line number Diff line
@@ -1394,6 +1394,8 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr, 
	TCP_SKB_CB(skb)->tcp_tw_isn = 0;

	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);

	TCP_SKB_CB(skb)->sacked = 0;

	TCP_SKB_CB(skb)->has_rxtstamp =

			skb->tstamp || skb_hwtstamps(skb)->hwtstamp;

}



static int tcp_v6_rcv(struct sk_buff *skb)

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