Author: andre Date: Fri Jul 5 14:24:37 2013 New Revision: 252786 URL: http://svnweb.freebsd.org/changeset/base/252786
Log: MFC r249809: When doing RFC3042 limited transmit on the first on second duplicate ACK make sure we actually have new data to send. This prevents us from sending unneccessary pure ACKs. Reported by: Matt Miller <[email protected]> Modified: stable/9/sys/netinet/tcp_input.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/netinet/tcp_input.c ============================================================================== --- stable/9/sys/netinet/tcp_input.c Fri Jul 5 14:18:09 2013 (r252785) +++ stable/9/sys/netinet/tcp_input.c Fri Jul 5 14:24:37 2013 (r252786) @@ -2532,6 +2532,7 @@ tcp_do_segment(struct mbuf *m, struct tc u_long oldcwnd = tp->snd_cwnd; tcp_seq oldsndmax = tp->snd_max; u_int sent; + int avail; KASSERT(tp->t_dupacks == 1 || tp->t_dupacks == 2, @@ -2553,7 +2554,17 @@ tcp_do_segment(struct mbuf *m, struct tc */ break; } - (void) tcp_output(tp); + /* + * Only call tcp_output when there + * is new data available to be sent. + * Otherwise we would send pure ACKs. + */ + SOCKBUF_LOCK(&so->so_snd); + avail = so->so_snd.sb_cc - + (tp->snd_nxt - tp->snd_una); + SOCKBUF_UNLOCK(&so->so_snd); + if (avail > 0) + (void) tcp_output(tp); sent = tp->snd_max - oldsndmax; if (sent > tp->t_maxseg) { KASSERT((tp->t_dupacks == 2 && _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-stable-9 To unsubscribe, send any mail to "[email protected]"
