linux-kernel - Re: [PATCH] PCI / PM: Block races between runtime PM and system sleep

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Date:	Sat, 25 Jun 2011 22:39:24 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH] PCI / PM: Block races between runtime PM and system
 sleep

On Fri, 24 Jun 2011, Rafael J. Wysocki wrote:

> > > I'm still not clear on why the error handler needs to run at this time.
> > 
> > Because SATA ports are suspended with the help of the SCSI error handling
> > mechanism (which Tejun claims is the best way to do that).

> I've carried out this exercise to see how complicated it is going to be
> and it doesn't really seem to be _that_ complicated.  The appended patch
> illustrates this, but it hasn't been tested, so caveat emptor.

The patch is straightforward enough.  But will it be sufficient?

Suppose a SATA port is already in runtime suspend when the system sleep
starts.  Will the error handler be able to do its special job?  I don't
know...  It may turn out to be necessary for the SATA port to be
runtime resumed somewhere along the line.

Alan Stern

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