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From: Tejun Heo <>
To: "Srivatsa S. Bhat" <>
Subject: Re: [PATCH v2 2/4] PM/Freezer: Make thaw_processes() thaw only userspace tasks
Date: Mon, 30 Jan 2012 15:30:55 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Jan 31, 2012 at 04:44:48AM +0530, Srivatsa S. Bhat wrote:
> Currently the situation is:
> freeze_processes() - freezes only userspace tasks
> freeze_kernel_threads() - freezes only kernel threads
> thaw_kernel_threads() - thaws only kernel threads
> thaw_processes() - thaws *everything* (both userspace tasks and kernel threads)

Umm... I don't really get this.  Why is this a problem?  The list is
not even correct.  freeze_kernel_threads() doesn't freeze "only"
kernel threads.  It freezes all threads "including" kernel threads and
that's only natural because you can't freeze kernel threads without
freezing userland threads and of course you can't thaw userland
threads without thawing kernel threads.

The system simply won't work if you do it otherwise and making them
disjoint operations increases the chance of bugs.  These operations
are naturally enclosed within each other and trying to break them
apart isn't a good idea.

What's the problem you're trying to solve here?  I don't really see
code clean up.  Code is different but not necessarily cleaner and FWIW
it seems more unnatural and brittle to me.



  reply	other threads:[~2012-01-30 23:31 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 23:14 [PATCH v2 0/4] PM / Freezer: Fix the semantics of thaw_processes() and thaw_kernel_threads() Srivatsa S. Bhat
2012-01-30 23:14 ` [PATCH v2 1/4] PM/Freezer: Use thaw_kernel_threads() in preparation for changes to thaw_processes() Srivatsa S. Bhat
2012-01-30 23:14 ` [PATCH v2 2/4] PM/Freezer: Make thaw_processes() thaw only userspace tasks Srivatsa S. Bhat
2012-01-30 23:30   ` Tejun Heo [this message]
2012-01-31  0:09     ` Srivatsa S. Bhat
2012-01-31  0:12       ` Tejun Heo
2012-02-01 14:03       ` Pavel Machek
2012-01-30 23:15 ` [PATCH v2 3/4] PM/Hibernate: Thaw kernel threads in hibernation_snapshot() in error/test path Srivatsa S. Bhat
2012-01-30 23:15 ` [PATCH v2 4/4] PM/Hibernate: Refactor and simplify freezer_test_done Srivatsa S. Bhat

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