From: Eric Dumazet Date: Tue, 27 Jan 2026 12:38:27 +0000 (+0000) Subject: tcp: tcp_tx_timestamp() must look at the rtx queue X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=838eb9687691d29915797a885b861fd09353386e;p=thirdparty%2Fkernel%2Flinux.git tcp: tcp_tx_timestamp() must look at the rtx queue tcp_tx_timestamp() is only called at the end of tcp_sendmsg_locked() before the final tcp_push(). By the time it is called, it is possible all the copied data has been sent already (transmit queue is empty). If this is the case, use the last skb in the rtx queue. Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Link: https://patch.msgid.link/20260127123828.4098577-2-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index d95b5b8c1ffc..e4009158b908 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -501,6 +501,9 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc) struct sk_buff *skb = tcp_write_queue_tail(sk); u32 tsflags = sockc->tsflags; + if (unlikely(!skb)) + skb = skb_rb_last(&sk->tcp_rtx_queue); + if (tsflags && skb) { struct skb_shared_info *shinfo = skb_shinfo(skb); struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);