Re: Async resume patch (was: Re: [GIT PULL] PM updates for 2.6.33) [LWN.net]

From:		Linus Torvalds <torvalds-AT-linux-foundation.org>
To:		"Rafael J. Wysocki" <rjw-AT-sisk.pl>
Subject:		Re: Async resume patch (was: Re: [GIT PULL] PM updates for 2.6.33)
Date:		Tue, 8 Dec 2009 07:35:27 -0800 (PST)
Cc:		Alan Stern <stern-AT-rowland.harvard.edu>, Zhang Rui <rui.zhang-AT-intel.com>, LKML <linux-kernel-AT-vger.kernel.org>, ACPI Devel Maling List <linux-acpi-AT-vger.kernel.org>, pm list <linux-pm-AT-lists.linux-foundation.org>
Archive-link:		Article, Thread

On Tue, 8 Dec 2009, Rafael J. Wysocki wrote:
> 
> The wait queue plus the op_complete flag combo plays the role of the locking
> in the Linus' picture

Please just use the lock. Don't make up your own locking crap. Really. 

Your patch is horrible. Exactly because your locking is horribly 
mis-designed. You can't say things are complete from an interrupt, for 
example, since you made it some random bitfield, which has unknown 
characteristics (ie non-atomic read-modify-write etc).

The fact is, any time anybody makes up a new locking mechanism, THEY 
ALWAYS GET IT WRONG. Don't do it.

I suggested using the rwsem locking for a good reason. It made sense. It 
was simpler. Just do it that way, stop making up crap.

		Linus
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