From ad02c4f547826167a709dab8a89a1caefd2c1f50 Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Wed, 4 Jan 2017 11:19:34 -0500 Subject: [PATCH] tcp: provide timestamps for partial writes For TCP sockets, TX timestamps are only captured when the user data is successfully and fully written to the socket. In many cases, however, TCP writes can be partial for which no timestamp is collected. Collect timestamps whenever any user data is (fully or partially) copied into the socket. Pass tcp_write_queue_tail to tcp_tx_timestamp instead of the local skb pointer since it can be set to NULL on the error path. Note that tcp_write_queue_tail can be NULL, even if bytes have been copied to the socket. This is because acknowledgements are being processed in tcp_sendmsg(), and by the time tcp_tx_timestamp is called tcp_write_queue_tail can be NULL. For such cases, this patch does not collect any timestamps (i.e., it is best-effort). This patch is written with suggestions from Willem de Bruijn and Eric Dumazet. Change-log V1 -> V2: - Use sockc.tsflags instead of sk->sk_tsflags. - Use the same code path for normal writes and errors. Signed-off-by: Soheil Hassas Yeganeh Acked-by: Yuchung Cheng Cc: Willem de Bruijn Cc: Eric Dumazet Cc: Neal Cardwell Cc: Martin KaFai Lau Acked-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 2e3807d8eba8..ec97e4b4a62f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -429,7 +429,7 @@ EXPORT_SYMBOL(tcp_init_sock); static void tcp_tx_timestamp(struct sock *sk, u16 tsflags, struct sk_buff *skb) { - if (tsflags) { + if (tsflags && skb) { struct skb_shared_info *shinfo = skb_shinfo(skb); struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); @@ -958,10 +958,8 @@ new_segment: copied += copy; offset += copy; size -= copy; - if (!size) { - tcp_tx_timestamp(sk, sk->sk_tsflags, skb); + if (!size) goto out; - } if (skb->len < size_goal || (flags & MSG_OOB)) continue; @@ -987,8 +985,11 @@ wait_for_memory: } out: - if (copied && !(flags & MSG_SENDPAGE_NOTLAST)) - tcp_push(sk, flags, mss_now, tp->nonagle, size_goal); + if (copied) { + tcp_tx_timestamp(sk, sk->sk_tsflags, tcp_write_queue_tail(sk)); + if (!(flags & MSG_SENDPAGE_NOTLAST)) + tcp_push(sk, flags, mss_now, tp->nonagle, size_goal); + } return copied; do_error: @@ -1281,7 +1282,6 @@ new_segment: copied += copy; if (!msg_data_left(msg)) { - tcp_tx_timestamp(sk, sockc.tsflags, skb); if (unlikely(flags & MSG_EOR)) TCP_SKB_CB(skb)->eor = 1; goto out; @@ -1312,8 +1312,10 @@ wait_for_memory: } out: - if (copied) + if (copied) { + tcp_tx_timestamp(sk, sockc.tsflags, tcp_write_queue_tail(sk)); tcp_push(sk, flags, mss_now, tp->nonagle, size_goal); + } out_nopush: release_sock(sk); return copied + copied_syn;