Re: Soft-Lockup/Race in networking in 2.6.31-rc1+195 ( possibly?caused by netem)

David Miller
2009-07-04T01:55:59Z

From: Jarek Poplawski <jarkao2@gmail.com>
Date: Sat, 4 Jul 2009 00:56:40 +0200

> On Fri, Jul 03, 2009 at 01:22:20PM -0700, David Miller wrote:
>> Well, if you look at that commit the bisect pointed to Jarek, it is a
>> change which starts causing a situation which never happened before.
>> Namely, timers added on one cpu can be migrated and fire on another.
>>
>> So this could be exposing races in the networking that technically
>> always existed.
>
> I'm not sure I get your point; could you give some example?
> Actually, I've suspected races in timers code.

Let's say that a particular networking timer always gets
re-added on the cpu where the timer fires.

In that case, beforehand, no inter-cpu races could possibly
be tested. But with the new timer code, such races could
now be potentially triggered.