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From: David Brownell <david-b@pacbell.net>
To: David Newall <davidn@davidnewall.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
Alan Stern <stern@rowland.harvard.edu>,
linux-pm@lists.linux-foundation.org,
Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: [linux-pm] Fundamental flaw in system suspend, exposed by freezer removal
Date: Tue, 26 Feb 2008 01:16:17 -0800 [thread overview]
Message-ID: <200802260116.18142.david-b@pacbell.net> (raw)
In-Reply-To: <47C3CD15.1060908@davidnewall.com>
On Tuesday 26 February 2008, David Newall wrote:
>
> Hardware can be inserted and removed while we're in a suspend state; and
> there's nothing that we can do about it until we resume. Is it fair to
> say, then, that having started suspend, we could reasonably ignore any
> device insertion and removal, and handle it on resume?
"Ignore" seems a bit strong; those events may be wakeup triggers,
which would cause the hardware to make it a very short suspend state.
"Defer handling" is more to the point, be it by hardware or software.
> Presumably we need to scan for hardware changes on resume.
Not on most busses I work with; the hardware issues notifications
whenever the devices are removable.
Which is a Good Thing ... scanning, as you suggest, is inherently
not reliable. If a mouse is swapped, it likely doesn't matter a
lot whether it's the "same" or not.
But ... how about if some removable storage media was taken out,
updated on a different system, then restored before the resume?
Not many filesystems handle that sanely. You *really* want to
have hardware which reports disconnect/reconnect events, or which
physically prevents them (locked case etc).
- Dave
next prev parent reply other threads:[~2008-02-26 9:17 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-25 15:39 Alan Stern
2008-02-25 19:46 ` [linux-pm] " Alan Stern
2008-02-25 22:25 ` Rafael J. Wysocki
2008-02-25 23:37 ` Alan Stern
2008-02-26 0:07 ` Rafael J. Wysocki
2008-02-26 15:49 ` Alan Stern
2008-02-26 23:17 ` Rafael J. Wysocki
2008-02-27 16:03 ` Alan Stern
2008-02-27 19:50 ` Rafael J. Wysocki
2008-02-27 20:15 ` Alan Stern
2008-02-28 22:49 ` Alan Stern
2008-02-29 0:01 ` Rafael J. Wysocki
2008-02-29 14:26 ` Rafael J. Wysocki
2008-02-29 15:53 ` Alan Stern
2008-02-29 17:02 ` Rafael J. Wysocki
2008-02-29 18:42 ` Alan Stern
2008-02-29 21:57 ` Rafael J. Wysocki
2008-02-29 22:46 ` Alan Stern
2008-03-01 0:13 ` Rafael J. Wysocki
2008-03-01 15:30 ` Alan Stern
2008-03-02 13:37 ` Rafael J. Wysocki
2008-03-02 16:22 ` Alan Stern
2008-03-02 19:11 ` Rafael J. Wysocki
2008-03-03 3:54 ` Alan Stern
2008-03-03 16:32 ` Rafael J. Wysocki
2008-03-03 17:43 ` Alan Stern
2008-03-03 20:47 ` Rafael J. Wysocki
2008-03-03 22:48 ` Alan Stern
2008-03-03 22:56 ` Rafael J. Wysocki
2008-03-03 23:12 ` Alan Stern
2008-03-03 23:18 ` Rafael J. Wysocki
2008-02-26 7:13 ` David Brownell
2008-02-26 8:25 ` David Newall
2008-02-26 9:16 ` David Brownell [this message]
2008-02-26 13:36 ` David Newall
2008-02-26 15:58 ` Alan Stern
2008-02-25 22:24 ` Rafael J. Wysocki
2008-02-27 20:36 ` Benjamin Herrenschmidt
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