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    SubjectRe: [RFC][PATCH] netconsole: avoid deadlock on printk from driver code
    From: Vegard Nossum <>
    Date: Wed, 13 Aug 2008 11:53:24 +0200

    > [PATCH] netconsole: avoid deadlock on printk from driver code
    > I encountered a hard-to-debug deadlock when I pulled out the plug of my
    > RealTek 8139 which was also running netconsole: The driver wants to print
    > a "link down" message. However, this triggers netconsole, which wants to
    > print the message using the same device. Here is a backtrace:

    See my other reply, this is absolutely the wrong way to go about

    You only have two sane options:

    1) Defer the link status printk message into a deferred context,
    such as a workqueue, so that you can do it outside of the

    2) Do your locking differently so that the link status handling
    locking does not bisect the locking used for packet transmit
    in ->hard_start_xmit().

    #2 is the reason why most other drivers don't have this silly
    bug, they don't hold TX path locks when handling link status
    and printing out such messages.

     \ /
      Last update: 2008-08-13 12:41    [W:0.020 / U:3.788 seconds]
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