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: Mike Maloney <maloney@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a995004..c614ff1 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -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 {

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index d25e3bc..0cce447 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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);
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d3421ee..568ccfd 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -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);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5af8b80..a63486a 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -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,

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d79a1af..abba3bc 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -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)