Re: [PATCH 1/3] PM: Introduce new top level suspend and hibernation callbacks (rev. 8)

[Rafael J. Wysocki]

On Monday, 14 of April 2008, Benjamin Herrenschmidt wrote:
> 
> > Please have a look at this thread:
> > http://lkml.org/lkml/2008/3/21/322
> > (in short, the reporter sees APM suspend breakage under stress, occuring
> > because APM uses our suspending of devices without the freezer).
> > 
> > It mostly appears to work without the freezer, but that's bacuse no one
> > actually does things that might break it.  I don't think we can rely on users
> > being so kind to us forever. :-)
> 
> As far as I'm concerned, it's yet another case of the freezer papering
> over a problem rather than fixing it properly.

Well, this is not a user's point of view.

> If we're going to introduce new callbacks, we should have the right
> semantic from day 1 -and- fix those problems, rather than going to the
> same old recursive nonsensical arguments and do things to paper over
> problems.

Still, we're not supposed to break things, as far as the functionality is
concerned, and that's important, because it means we _have_ _to_ make changes
in steps.

To be more precise, what you suggest (move ->prepare() before the freezer
right now) means a patch with _functional_ changes (it's impossible to register
new children of dev after ->prepare(dev) has run which can affect the user
space in the window before ->prepare() and the freezer), whereas what I'd like
to do is the (present) patch without functional changes.

Thanks,
Rafael
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