Date: Tue, 23 Apr 2013 14:06:33 +0000 (UTC) From: Andre Oppermann <andre@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r249809 - head/sys/netinet Message-ID: <201304231406.r3NE6X6u044738@svn.freebsd.org>
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Author: andre Date: Tue Apr 23 14:06:32 2013 New Revision: 249809 URL: http://svnweb.freebsd.org/changeset/base/249809 Log: 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 <matt@matthewjmiller.net> Tested by: Matt Miller <matt@matthewjmiller.net> MFC after: 2 weeks Modified: head/sys/netinet/tcp_input.c Modified: head/sys/netinet/tcp_input.c ============================================================================== --- head/sys/netinet/tcp_input.c Tue Apr 23 13:33:13 2013 (r249808) +++ head/sys/netinet/tcp_input.c Tue Apr 23 14:06:32 2013 (r249809) @@ -2564,6 +2564,7 @@ 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, @@ -2585,7 +2586,17 @@ 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 &&
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