linux-kernel - Re: [PATCH] PM: Fix dev_pm_put_subsys_data() to not call kfree() while holding device power lock

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Message-ID: <1367848858.2953.1.camel@lorien>
Date:	Mon, 6 May 2013 14:01:03 +0000
From:	Shuah Khan <shuah.kh@...sung.com>
To:	Pavel Machek <pavel@....cz>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	"len.brown@...el.com" <len.brown@...el.com>,
	"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"shuahkhan@...il.com" <shuahkhan@...il.com>
Subject: Re: [PATCH] PM: Fix dev_pm_put_subsys_data() to not call kfree()
 while holding device power lock

On Mon, 2013-05-06 at 14:09 +0200, Pavel Machek wrote:
> Hi!
> 
> > > Wow, that function is fragile. It returns 0/1/-EINVAL, while being
> > > documented for 0/1...
> > 
> > Oh, it generally should return 1 for !psd.
> > 
> > > Patch does not look obviously wrong, but maybe 
> > > 
> > > @@ -73,13 +73,17 @@ int dev_pm_put_subsys_data(struct device *dev)
> > >  
> > >  	if (--psd->refcount == 0) {
> > >  		dev->power.subsys_data = NULL;
> > > +		spin_unlock_irq(&dev->power.lock);
> > > -		kfree(psd);
> > > - 		ret = 1;
> > > +		return 1;
> > >  	}
> > > 
> > > Would be cleaner.
> > 
> > What about this:
> 
> Looks good to me.
> 
> Reviewed-by: Pavel Machek <pavel@....cz>

Rafael/Pavel,

I redid the patch based on Pavel's comments and just about to send it
and then I saw your exchange. This version looks good to me. Do you want
me to test the patch and resend?

thanks,
-- Shuah