linux-kernel - Re: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in pm_runtime_get

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Message-ID: <1500812.76gqUM2HnU@vostro.rjw.lan>
Date:	Fri, 01 Mar 2013 03:22:21 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
Cc:	"Li, Fei" <fei.li@...el.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"Lan, Tianyu" <tianyu.lan@...el.com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"sarah.a.sharp@...ux.intel.com" <sarah.a.sharp@...ux.intel.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in pm_runtime_get_sync failed case

On Friday, March 01, 2013 02:07:54 AM Liu, Chuansheng wrote:
> 
> > -----Original Message-----
> > From: Li, Fei
> > Sent: Thursday, February 28, 2013 5:06 PM
> > To: gregkh@...uxfoundation.org; Lan, Tianyu; stern@...land.harvard.edu;
> > sarah.a.sharp@...ux.intel.com
> > Cc: rjw@...k.pl; linux-usb@...r.kernel.org; linux-kernel@...r.kernel.org; Liu,
> > Chuansheng; Li, Fei
> > Subject: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in
> > pm_runtime_get_sync failed case
> > 
> > 
> > Even in failed case of pm_runtime_get_sync, the usage_count
> > is incremented. In order to keep the usage_count with correct
> > value and runtime power management to behave correctly, call
> > pm_runtime_put(_sync) in such case.
> > 
> > Signed-off-by Liu Chuansheng <chuansheng.liu@...el.com>
> > Signed-off-by: Li Fei <fei.li@...el.com>
> > ---
> >  drivers/usb/core/hub.c |    3 ++-
> >  1 files changed, 2 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> > index 5480352..f72dede 100644
> > --- a/drivers/usb/core/hub.c
> > +++ b/drivers/usb/core/hub.c
> > @@ -3148,12 +3148,13 @@ int usb_port_resume(struct usb_device *udev,
> > pm_message_t msg)
> > 
> >  	if (port_dev->did_runtime_put) {
> >  		status = pm_runtime_get_sync(&port_dev->dev);
> > -		port_dev->did_runtime_put = false;
> >  		if (status < 0) {
> >  			dev_dbg(&udev->dev, "can't resume usb port, status %d\n",
> >  					status);
> > +			pm_runtime_put_sync(&port_dev->dev);
> Rechecked the usb similar codes, in usb_autoresume_device() and usb_autopm_get_interface(),
> when pm_runtime_get_sync() failed, the paired pm_runtime_put_sync() will be called.
> Alan and Rafael, is it reasonable to consider this cleanup patch also? Thanks.

You can very well use pm_runtime_put_noidle() here too.  Then, it will
be kind of clear what it's for.

> 
> >  			return status;
> >  		}
> > +		port_dev->did_runtime_put = false;
> >  	}
> > 
> >  	/* Skip the initial Clear-Suspend step for a remote wakeup */
> > --
> > 1.7.4.1

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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