linux-kernel - Re: [PATCH 0/8] Suspend block api (version 7)

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Message-ID: <AANLkTim2b8cKnzPgN7m5zImb0hVDfqVjRidKNVoYi1yO@mail.gmail.com>
Date:	Mon, 17 May 2010 13:51:16 -0700
From:	Brian Swetland <swetland@...gle.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Arve Hjønnevåg <arve@...roid.com>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] Suspend block api (version 7)

On Mon, May 17, 2010 at 1:40 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Monday 17 May 2010, Arve Hjønnevåg wrote:
>>
>> It should get out of that loop as soon as someone blocks suspend. If
>> someone is constantly aborting suspend without using a suspend blocker
>> it will be very inefficient, but it should still work.
>
> Well, the scenario I have in mind is the following.  Someone wants to check
> the feature and simply writes "opportunistic" to /sys/power/policy and "mem" to
> /sys/power/state without any drivers or apps that use suspend blockers.
>
> How in that case is the system supposed to break out of the suspend-resume loop
> resulting from this?  I don't see right now, because the main blocker is
> inactive, there are no other blockers that can be activated and it is next to
> impossible to write to /sys/power/state again.

I guess we could set a flag when a suspend blocker is registered and
refuse to enter opportunistic mode if no blockers have ever been
registered.

It does seem like extra effort to go through to handle a "don't do
that" type scenario (entering into opportunistic suspend without
anything that will prevent it).

Brian
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