DragonFly commits List (threaded) for 2010-12
git: tcp: Don't allow persist timer if TCP connection is not established yet
Author: Sepherosa Ziehau <email@example.com>
Date: Tue Dec 21 16:26:34 2010 +0800
tcp: Don't allow persist timer if TCP connection is not established yet
This probably could move the un-updated snd_nxt panic earlier.
The dump of the panic in http://bugs.dragonflybsd.org/issue1939 shows
- snd_nxt is less than snd_una
- A persist timer was fired (frame 16, tp->tt_msg->tt_prev_tasks).
- The TCP segment triggered the panic has SYN|ACK (frame 17, th->th_flags).
This TCP segment is considered as valid (frame 17, list), so tp->t_state
This explains why snd_nxt is less than snd_una:
If tcp_output() is called by persist timer, then the persist timer is
active and the "forced" is turned on, this causes the snd_nxt not updated
MISSING CHIAN IN THE LINK:
How is the persist timer got set in the SYN_SENT in the first place?
Hope the new panic could lift the veil...
Summary of changes:
sys/netinet/tcp_output.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
DragonFly BSD source repository