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From: NeilBrown <neilb@suse.de>
To: markgross@thegnar.org
Cc: linux-kernel@vger.kernel.org,
	John Stultz <john.stultz@linaro.org>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	arve@android.com, Alan Stern <stern@rowland.harvard.edu>,
	amit.kucheria@linaro.org, farrowg@sg.ibm.com,
	"Dmitry Fink (Palm GBU)" <Dmitry.Fink@palm.com>,
	linux-pm@lists.linux-foundation.org, khilman@ti.com,
	Magnus Damm <damm@opensource.se>,
	mjg@redhat.com, peterz@infradead.org
Subject: Re: [markgross@thengar.org: [RFC] wake up notifications and suspend blocking (aka more wakelock stuff)]
Date: Sat, 8 Oct 2011 22:14:39 +1100	[thread overview]
Message-ID: <20111008221439.48f30263@notabene.brown> (raw)
In-Reply-To: <20111002164456.GC14312@mgross-G62>

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On Sun, 2 Oct 2011 09:44:56 -0700 mark gross <markgross@thegnar.org> wrote:

> resending to wider list for discussion
> ----- Forwarded message from mark gross <markgross@thengar.org> -----
> 
> Subject: [RFC] wake up notifications and suspend blocking (aka more wakelock stuff)
> Date: Tue, 20 Sep 2011 13:33:05 -0700
> From: mark gross <markgross@thengar.org>
> To: linux-pm@lists.linux-foundation.org
> Reply-To: markgross@thegnar.org
> Cc: arve@android.com, markgross@thegnar.org, Alan Stern <stern@rowland.harvard.edu>, amit.kucheria@linaro.org, farrowg@sg.ibm.com, "Rafael J. Wysocki" <rjw@sisk.pl>
> 
> The following patch set implement an (untested) solution to the
> following problems.
> 
> 1) a method for making a system unable to suspend for critical sections
> of time.

We already have this.  A properly requested suspend (following wakeup_count
protocol) is unable to complete between wakeup_source_activate() and
wake_source_deactivate() - these delimit the critical sections.

What more than this do you need?

If user-space wants to prevent suspend, it just needs some sort of protocol
for talking to the user-space process which follows the correct protocol to
initiate suspend.  That isn't a kernel problem.

> 
> 2) providing a race free method for the acknowledgment of wake event
> processing before re-entry into suspend can happen.

Again, this is a user-space problem.  It is user-space which requests
suspend.  It shouldn't request it until it has checked that there are no wake
events that need processing - and should use the wakeup_count protocol to
avoid races with wakeup events happening after it has checked.

i.e. there is no kernel-space problem to solve here (except for possible
bugs).

NeilBrown


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  reply	other threads:[~2011-10-08 11:15 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-02 16:44 [markgross@thengar.org: [RFC] wake up notifications and suspend blocking (aka more wakelock stuff)] mark gross
2011-10-08 11:14 ` NeilBrown [this message]
2011-10-08 18:16   ` mark gross
2011-10-08 18:57     ` Rafael J. Wysocki
2011-10-08 20:07       ` Alan Stern
2011-10-13  3:07         ` mark gross
2011-10-13 15:06           ` Alan Stern
2011-10-14 13:23             ` mark gross
2011-10-13  2:59       ` mark gross
2011-10-08 22:31     ` NeilBrown
2011-10-13  3:48       ` mark gross
2011-10-13  5:35         ` NeilBrown
2011-10-13 15:16           ` Alan Stern
2011-10-14 21:47             ` NeilBrown
2011-10-15 18:45               ` Alan Stern
2011-10-15 22:25                 ` NeilBrown
2011-10-16  1:49                   ` Alan Stern
2011-10-16 21:37                     ` NeilBrown
2011-10-24  1:18                       ` mark gross
2011-10-24  1:50                         ` NeilBrown
2011-10-25  4:50                           ` mark gross
2011-10-25 15:14                             ` Alan Stern
2011-10-25  7:05                           ` Brian Swetland
2011-10-14 14:01           ` mark gross
2011-10-15 14:05             ` mark gross
2011-10-15 22:12               ` NeilBrown

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