Re: System blocks (hangs) on ifconfig up

[Eric Dumazet <eric.dumazet@gmail.com>]

Le dimanche 12 décembre 2010 à 17:08 +0200, Shmulik Hen a écrit :
> Hello,
> 
> My system is Ubuntu 10.04, running kernel 2.6.32-26-generic.
> 
> Whenever I try to bring up a specific ethernet interface for the second 
> time, my
> system becomes unresponsive for 60 seconds - i.e. no mouse, no keyboard, no
> screen refresh. etc.
> 
> Looking at the driver's code, I could see that it's dev->open() method 
> calls
> wait_event_interruptible_timeout() with a timeout of 60 seconds - exactly
> the delay I'm seeing.
> 

What is this driver ?

> I have narrowed the code to a bare minimum (see below - loosely based on
> dummy.c), which only calls mdelay(10000) in it's dev->open() method, and
> still, my system blocks for exactly 10 seconds when I run the following
> sequence:
> 
>  > sudo ifconfig shmulik0 up
>  > sudo ifconfig shmulik0 down
>  > sudo ifconfig shmulik0 up
> 
> At this point - the system is stuck for 10 seconds.
> 

Certainly not "stuck for 10 seconds"

mdelay(10000) suspends this task for 10 seconds, but other tasks can
certainly run.

However, your shell waits that "ifconfig ... up" finishes.