Re: [RFC PATCH 1/3] block: add a flag to identify PM request
From: Alan Stern
Date: Tue May 15 2012 - 12:03:57 EST
On Tue, 15 May 2012, Lin Ming wrote:
> On Tue, 2012-05-15 at 10:35 -0400, Alan Stern wrote:
> > On Tue, 15 May 2012, Lin Ming wrote:
> > > Add a flag REQ_PM to identify the request is PM related.
> > > As an example, modify scsi code to use this flag.
> > There already is such a flag; you don't need to add one. In fact,
> > there already are _two_ such flags, and it would be best to remove one
> > of them. In include/linux/blkdev.h:
> > REQ_TYPE_PM_SUSPEND, /* suspend request */
> > REQ_TYPE_PM_RESUME, /* resume request */
> > Apparently they had been used by the old ide driver, but they don't
> > seem to be used anywhere now.
> IDE code still uses both types and they are used for system
> suspend/resume. See generic_ide_suspend and generic_ide_resume.
You're right, of course. I searched for "BLK_TYPE_PM_" instead of
> But we need a flag to check whether it is runtime suspend/resume
It should be possible to fix up the IDE code so that it uses the same
flag for both suspend and resume. After all, there's no real danger of
confusion -- you never get into a situation where you're not sure
whether the current PM action is a suspend or a resume.
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