svn commit: r229665 - head/sys/netinet
John Baldwin
jhb at FreeBSD.org
Thu Jan 5 22:29:12 UTC 2012
Author: jhb
Date: Thu Jan 5 22:29:11 2012
New Revision: 229665
URL: http://svn.freebsd.org/changeset/base/229665
Log:
Remove the assertion from tcp_input() that rcv_nxt is always greater
than or equal to rcv_adv and fix tcp_twstart() to handle this case by
assuming the last window was zero rather than a negative value.
The code in tcp_input() already safely handled this case. It can happen
due to delayed ACKs along with a remote sender that sends data beyond
the window we previously advertised. If we have room in our socket buffer
for the extra data beyond the advertised window, we will accept it.
However, if the ACK for that segment is delayed, then we will not
effectively fixup rcv_adv to account for that extra data until the
next segment arrives and forces out an ACK. When that next segment
arrives, rcv_nxt will be beyond rcv_adv.
Tested by: pjd
MFC after: 1 week
Modified:
head/sys/netinet/tcp_input.c
head/sys/netinet/tcp_timewait.c
Modified: head/sys/netinet/tcp_input.c
==============================================================================
--- head/sys/netinet/tcp_input.c Thu Jan 5 22:28:40 2012 (r229664)
+++ head/sys/netinet/tcp_input.c Thu Jan 5 22:29:11 2012 (r229665)
@@ -1795,9 +1795,6 @@ tcp_do_segment(struct mbuf *m, struct tc
win = sbspace(&so->so_rcv);
if (win < 0)
win = 0;
- KASSERT(SEQ_GEQ(tp->rcv_adv, tp->rcv_nxt),
- ("tcp_input negative window: tp %p rcv_nxt %u rcv_adv %u", tp,
- tp->rcv_nxt, tp->rcv_adv));
tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt));
/* Reset receive buffer auto scaling when not in bulk receive mode. */
Modified: head/sys/netinet/tcp_timewait.c
==============================================================================
--- head/sys/netinet/tcp_timewait.c Thu Jan 5 22:28:40 2012 (r229664)
+++ head/sys/netinet/tcp_timewait.c Thu Jan 5 22:29:11 2012 (r229665)
@@ -242,10 +242,10 @@ tcp_twstart(struct tcpcb *tp)
/*
* Recover last window size sent.
*/
- KASSERT(SEQ_GEQ(tp->rcv_adv, tp->rcv_nxt),
- ("tcp_twstart negative window: tp %p rcv_nxt %u rcv_adv %u", tp,
- tp->rcv_nxt, tp->rcv_adv));
- tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
+ if (SEQ_GE(tp->rcv_adv, tp->rcv_nxt))
+ tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
+ else
+ tw->last_win = 0;
/*
* Set t_recent if timestamps are used on the connection.
More information about the svn-src-head
mailing list