Re: [PATCH v2 03/10] freezer: add new freezable helpers using freezer_do_not_count()

From: Colin Cross
Date: Thu May 02 2013 - 22:17:09 EST


This sounds the same as what ended up getting reverted in
https://lkml.org/lkml/2013/3/4/221
I can add the WARN_ON_ONCE to all my new calls, and leave them out of
existing calls, but that seems a little odd, and will be redundant if
the lockdep call in try_to_freeze goes back in in 3.11. Do you still
want it in the new apis?

On Thu, May 2, 2013 at 5:03 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> On Thu, May 02, 2013 at 04:55:05PM -0700, Tejun Heo wrote:
>> So, the freezable interface can't be something that people can use
>> casually. It is something which should be carefully and strategically
>> deployed where we *know* that lock dependency risks don't exist or at
>> least are acceptable. I'm a bit weary that this patch is expanding
>> the interface a lot that they now look like the equivalents of normal
>> schedule calls. Not exactly sure what to do here but can we please at
>> least have RED BOLD BLINKING comments which scream to people not to
>> use these unless they know what they're doing?
>
> Maybe we should trigger WARN_ON_ONCE() if lockdep_depth() > 0 by
> default and have ugly variants which can be used if the caller is sure
> that it's okay possibly with list of locks which are held?
>
> --
> tejun
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