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    Subjectdouble lock on socket
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    Now, I know the double lock on socket message is supposed to not
    mean anything anymore... matter of fact, the message appears to
    be disabled in standard code....

    But, a while back, I'd hacked linux/net/sock.h to make the
    lock_sock() not just print a double lock occured, but where the
    current and prev locks happened.

    Not seen such a message in a while, but I finally did today with
    1.99.7. I saw the following when I type into a VC that had an
    rlogin session that had been idle for a while [formatted to fit
    under 80 chars]

    May 28 18:51:22 thune kernel: double lock on socket at tcp.c:1162, \
    prev lock at tcp.c:1440

    Now, in that file, line 1162 is in tcp_sendmsg() (just prior to
    the discussion of Nagle's rule); line 1440 is in tcp_recvmsg()
    (just prior to found_on_skb: label).

    I must admit, I don't understand the networking code thoroughly.
    However, it appears that there is no obvious path from that point
    in tcp_recvmsg() to tcp_sendmsg() that does not go through
    release_sock().

    I'm still a bit confused on how a process accessing the network,
    that has been paged out, could cause this scenario....

    If that has been discussed before, a pointer to the message-id
    (and a working website that has them archived... last time i
    tried homer.ncm.com, it wasn't working), I'll reread the
    discussion myself.

    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


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