double lock on socket

Mike Castle (mcastle@umr.edu)
Mon, 4 Mar 1996 14:12:45 -0600 (CST)


Hmmmm... I've gotten double lock on socket at ..... twice in a
few minutes with kernel 1.3.70. In function tcp_sendmesg().

It's a mostly ELF system, both a.out and elf compiled in (not
tried a.out as module yet), but everything else is a module.

Using kerneld 1.3.57 and dip with cslip to connect to campus dialups.
kerneld runs dip to give ondemand dial in. I use
IPMASQ on machine with modem (ylum) to allow other machine
(thune) to access network.

Sitting at thune's console. Had one vt logged in as root and
rshed to ylum. On another vt, had user logged in running screen
and multiple sessions to the net (telnets, lynx, ftp).
Occasionally I'd switch to the vt with root rshed to ylum, and as
soon as I'd hit a key, I'd get the double lock message.

The message is generated on thune.

Hmmm... upon looking in /var/log/messages, I see the following:

Mar 4 12:06:54 thune linux: 5>double lock on socket at 00134a94
Mar 4 12:52:09 thune linux: 5>double lock on socket at 0013f2d7
Mar 4 13:35:39 thune linux: 5>double lock on socket at 0013f2d7

The last two are tcp_sendmesg() and were noticed in the scenario
above. I don't remember seeing the other message, though may
have been scrolled off. But the conditions where the same.
00134a94 corresponds to skb_recv_datagram().

Machine seems to work fine. I'll try to pound on things when I
get 71 compiled and see if I can generate a set of circumstances
that will always create it.

mrc

-- 
Mike Castle .-=NEXUS=-.  Life is like a clock:  You can work constantly
  mcastle@cs.umr.edu     and be right all the time, or not work at all
   mcastle@umr.edu       and be right at least twice a day.  -- mrc
    We are all of us living in the shadow of Manhattan.  -- Watchmen