How2 kill pppd without pulling-plug?

Discussion in 'Linux Networking' started by Avoid9Pdf, Jul 11, 2012.

  1. Avoid9Pdf

    Avoid9Pdf Guest

    I remember reading how some Soviet-scammers, made people's modems
    auto-dial Moldovia, and the expensive call costs went partly to the scammers.

    Since then I just pull the plug.
    And I've got the POTS-dial-up modem set to *sound*.

    Now this fixed-radio-terminal-modem which goes via ttyUSB0, can't
    re-connect after I disconnect-the-USBline, until I reboot.

    It was previously OK, under Slak13, until that crashed the IDE and
    I've been using old-FC1.

    There's a kernel problem and apparently a mem-leak, because
    it slowly <disconnects pid/S after I've pulled-the-line>.

    Here's `tail /var/log/messages` :-
    Jul 11 19:08:50 localhost pppd[28712]: secondary DNS address 41.164.0.11 <-last good line
    Jul 11 19:23:57 localhost kernel: usb.c: USB disconnect on device 00:0f.0-1 address 4
    Jul 11 19:23:57 localhost kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000998
    Jul 11 19:23:57 localhost kernel: printing eip:
    Jul 11 19:23:57 localhost kernel: caef656c
    Jul 11 19:23:57 localhost kernel: *pde = 00000000
    Jul 11 19:23:57 localhost kernel: Oops: 0002
    Jul 11 19:23:57 localhost kernel: ppp_deflate ppp_async ppp_generic slhc usbserial vfat fat soundcore r128 agpgart reiserfs parport_pc lp parport autofs ipt_REJECT ipt_state ip_conntrack iptab
    Jul 11 19:23:57 localhost kernel: CPU: 0
    ....
    Jul 11 19:23:57 localhost kernel: [<c8a095c0>] usb_hub_thread [usbcore] 0x0 (0xc60b3fe0)
    Jul 11 19:23:57 localhost kernel: [<c010741d>] kernel_thread_helper [kernel] 0x5 (0xc60b3ff0)
    Jul 11 19:23:57 localhost kernel:
    Jul 11 19:23:57 localhost kernel:
    Jul 11 19:23:57 localhost kernel: Code: 89 90 98 09 00 00 8d 4e 58 ff 43 74 0f 8e 96 05 ...

    Also why can't I
    `kill -9 <pppd-pid>` ?

    If I leave the USB-line connected it goes on-line by itself, every few minutes.
    What the hell is that?!

    == TIA.
     
    Avoid9Pdf, Jul 11, 2012
    #1
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  2. Avoid9Pdf

    Moe Trin Guest

    FOLLOWUP SET

    Sweet Mother of Ghod, Chris - how long have you been using *nix? And
    you haven't learned about shutting down gracefully? Are you going
    completely senile? Or just trolling?
    Because when you do that, you don't give things time to exit cleanly.
    RTFM "man kill" It's leaving shit scattered about your file
    system, like lock files. If you absolutely must use kill (or killall)
    use -15 as the signal, NOT MINUS NINE.
    So your system is p0wn3d - maybe - try 'ps afuwwwx' and look to see
    what process started what. Also kick your pppd and include the 'dump'
    option to see what options you've attempting to use. See the man page.

    Old guy
     
    Moe Trin, Jul 12, 2012
    #2
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  3. The drivers clearly don't take kindly to having the hardware yanked
    away. If you have the source for the drivers and the time to
    investigate the problems they have, you might be able to repair them to
    your liking. Otherwise, don't do that.
    If a user thread (such as pppd) invokes a kernel interface that blocks,
    it can block in an uninterruptible manner. When that happens, you
    cannot kill the process because it can't be interrupted.

    In other words, it's due to the kernel bugs noted above that were
    triggered by the action of pulling out the USB cable on a live connection.
    Dunno. Any chance you can post configuration information? By default,
    pppd doesn't do that, but there are options you can configure ("demand"
    and "persist" are the main ones) that will cause it to retry after a
    disconnect.

    Since it's not the default, it has to be somewhere in your pppd
    configuration files and/or command line options.
     
    James Carlson, Jul 17, 2012
    #3
  4. Avoid9Pdf

    Avoid9Pdf Guest

    I expect USB to be plug-and-play-able?
    It was on my knl2.6* linux.
    OK thanks, that's the deeper explanation that I wanted.
    Adding `demand nopersist` to my 90s-old script, which I've
    been using before I read your book at the Johannesburg
    reference library [**], I'm now able to `killall pppd`.
    And then I'm now able to pull-out the USB-line.
    Which previously gave <kernel errors /problems> on this
    knl 2.4*, since my knl 2.6* has crashed. Knl2.6* could handle it;
    which is what also confused me.

    I don't trust the system/s.
    Going on line, is like a rocket-launch or a taxi-journey:
    when it's finished, I must disconnect.

    == Chris Glur.

    [**] since the <revolutionary-natives-party> was handed
    power, they've closed the previously brilliant ,30's built,
    reference library, and I've heard that by mistake some
    AA employee pulped many of the valuable books. A lot of the
    new books are cartoon-based. Which perhaps makes sense
    since the controlling-natives have never had a written language.
    Today' BBC news was explaining how S. Italy's local government &
    municipal authorities are similarly corrupt.
    Be happy don't worry.
     
    Avoid9Pdf, Jul 19, 2012
    #4
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