Re: [PATCH 2/3] stop_machine: dequeue work before signal completion

From: Tejun Heo
Date: Wed Feb 06 2013 - 21:29:13 EST


Hello,

On Wed, Feb 6, 2013 at 6:21 PM, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>> Why does this matter? It's inside spinlock. What's being made better
>> by this change?
>
> IIUC the work should be deleted from the list, otherwise it'd trigger
> BUG_ON when the cpu gets online again.

Ah, okay, the original code was missing list_del_init(), so we end up
with trashy work list if CPU goes down while there are pending work
items which will trigger BUG_ON() later when the CPU comes back on.

Hillf, can you please redo the patch description? I can't tell what
the patch is about from the description at all. If it's a bug fix,
describe the bug and maybe accompany with oops trace if possible, and
then describe how it's fixed.

Thanks.

--
tejun
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