From: Tejun Heo <tj@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jan Kara <jack@suse.cz>, Peter Chen <hzpeterchen@gmail.com>,
florian@mickler.org, jkosina@suse.cz,
Linux-pm mailing list <linux-pm@vger.kernel.org>
Subject: Re: Should suspend plug low-level devices?
Date: Sun, 20 Mar 2016 14:29:58 -0400 [thread overview]
Message-ID: <20160320182958.GR20028@mtj.duckdns.org> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1603181651400.1866-100000@iolanthe.rowland.org>
Hello,
On Fri, Mar 18, 2016 at 05:06:01PM -0400, Alan Stern wrote:
> The original problem here was that some unfreezable code was waiting
> (via flush_delayed_work) on frozen code, and it was blocking the
> routine that would unfreeze things. Therefore the order of freezing or
> thawing has no bearing on this particular problem.
Yeah, this one is caused by a high-level kernel construct being frozen
and device resuming as a whole taking place before unfreezing. The
eventual goal would be avoiding freezing any high-level kernel
constructs as it can lead to circular dependencies as shown here.
> Now, I have nothing against finer-grained control of freezing, although
> I'm not sure how you would implement it in cases where a kthread is not
> per-device but rather is per-driver or per-subsystem. But we will
> still have to handle inversions where unfreezable code is waiting for
> frozen code.
It won't be simple one-to-one conversion for all cases. It's about
terminating suspend handling where the endpoints actually are after
all.
thanks.
--
tejun
next prev parent reply other threads:[~2016-03-20 18:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160316150053.GG6980@mtj.duckdns.org>
2016-03-16 15:37 ` Should suspend plug low-level devices? Alan Stern
2016-03-16 16:31 ` Rafael J. Wysocki
2016-03-16 16:35 ` Tejun Heo
2016-03-16 16:39 ` Rafael J. Wysocki
2016-03-16 23:18 ` Jiri Kosina
2016-03-16 23:24 ` Rafael J. Wysocki
2016-03-16 23:42 ` Jiri Kosina
2016-03-16 23:48 ` Rafael J. Wysocki
2016-03-17 7:50 ` Oliver Neukum
2016-03-17 8:02 ` Jiri Kosina
2016-03-17 8:20 ` Oliver Neukum
2016-03-17 8:35 ` Jiri Kosina
2016-03-17 9:12 ` Oliver Neukum
2016-03-17 10:20 ` Jiri Kosina
2016-03-17 10:29 ` Oliver Neukum
2016-03-17 10:36 ` Jiri Kosina
2016-03-17 18:55 ` Alan Stern
2016-03-18 20:29 ` Tejun Heo
2016-03-17 0:05 ` Tejun Heo
2016-03-17 18:58 ` Alan Stern
2016-03-18 20:25 ` Tejun Heo
2016-03-17 18:53 ` Alan Stern
2016-03-18 20:29 ` Tejun Heo
2016-03-16 16:34 ` Tejun Heo
2016-03-17 18:51 ` Alan Stern
2016-03-18 20:32 ` Tejun Heo
2016-03-18 21:06 ` Alan Stern
2016-03-20 18:29 ` Tejun Heo [this message]
2016-03-21 14:38 ` Alan Stern
2016-03-30 17:09 ` Tejun Heo
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