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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.

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