Re: Alternative to TIF_FREEZE -> a notifier in the task_struct?

[Pavel Machek <pavel@suse.cz>]

Hi!

> This could be used to have a process execute any other piece that is 
> required to run in the context of the thread. Maybe such a feature could 
> help with PTRACE or/and get_user_pages that currently do ugly things to a 
> process. It may also allow changing values that so far cannot be
> changed from the outside in the task struct by running a function
> in the context of the process.

Well, we really need slightly more from "running in process context":
we also need "no locks held" for swsusp. (But other uses probably do,
too?)

> Here is a patch against Linus current tree that does this. Note that this 
> patch is incomplete at this point and only a basis for further discussion. 
> Not all software suspend checkpoints are useful for a notifier chain. We 
> would need to inspect several cases where drivers/kernel threads have 
> special functionality for software suspend.

I guess I'd prefer if you left "refrigerator()" and "try_to_freeze()"
functions in; there are about 1000 drivers that know/use them, and
some patches are probably in the queue....

								Pavel
-- 
teflon -- maybe it is a trademark, but it should not be.
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