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Date: Thu, 27 May 2010 21:02:17 +0100
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>,
       Alan Stern <stern@rowland.harvard.edu>,
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       Linux PM <linux-pm@lists.linux-foundation.org>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
Message-ID: <20100527200217.GA7449@srcf.ucam.org>
References: <Pine.LNX.4.44L0.1005271344040.3239-100000@iolanthe.rowland.org> <1274982779.27810.5708.camel@twins> <20100527175719.GD3543@srcf.ucam.org> <1274983333.27810.5744.camel@twins> <20100527181433.GG3543@srcf.ucam.org> <20100527200313.5c532f2f@lxorguk.ukuu.org.uk> <20100527191302.GC5703@srcf.ucam.org> <20100527205009.391803b6@lxorguk.ukuu.org.uk>
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On Thu, May 27, 2010 at 08:50:09PM +0100, Alan Cox wrote:

> So I guess if you are driving this rom user space (which I take it you
> are given you talk about housekeeping)
> 
> 	foreach app we need to suspend
> 		kick app to suspend (signal)
> 		(policy) kick harder if needed (SIGSTOP/bitch/shall I
> 					kill it dialogue)

This would need to be atomic, but in any case:

1) Policy decision is made
2) Wakeup event is received by task
3) Task gets stopped between receiving the event and handing it off to 
policy agent

At which point you suspend when you should have remained awake.

-- 
Matthew Garrett | mjg59@srcf.ucam.org