linux-kernel - Re: [PATCH] power: Change device_wakeup_enable() to check for null dev

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Date:	Fri, 15 Nov 2013 16:25:01 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Shuah Khan <shuah.kh@...sung.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>, len.brown@...el.com,
	pavel@....cz, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, shuahkhan@...il.com,
	anton@...msg.org, dwmw2@...radead.org, stable@...r.kernel.org
Subject: Re: [PATCH] power: Change device_wakeup_enable() to check for null
 dev_name(dev)

On Fri, Nov 15, 2013 at 05:16:31PM -0700, Shuah Khan wrote:
> On 11/15/2013 05:21 PM, Rafael J. Wysocki wrote:
> > On Friday, November 15, 2013 05:03:57 PM Shuah Khan wrote:
> >> device_wakeup_enable() uses dev_name(dev) as the wakeup source name.
> >> When it gets called with a device with its name not yet set, ws structure
> >> with ws->name = NULL gets created.
> >>
> >> When kernel is booted with wakeup_source_activate enabled, it will panic
> >> when the trace point code tries to derefernces ws->name.
> >>
> >> Change device_wakeup_enable() to check for dev_name(dev) null condition
> >> and return -EINVAL to avoid panics when device_wakeup_enable() gets called
> >> before device is fully initialized with its name.
>   		return -EINVAL;
> >
> > Can you please use WARN_ON(!dev_name(dev)) here?  While I agree that it is a
> > bad idea to crash the kernel because dev has no name, that indicates a driver
> > bug that shouldn't be too easy to ignore.
> >
> > Thanks!
> >
> 
> Right. ok I will re-cut the patch with WARN_ON and send it. fyi I did 
> send fix for the driver (power_supply) as well.
> 
> http://www.kernelhub.org/?msg=362354&p=2

Why is a driver calling kobject_set_name() instead of device_set_name()?

Yes, it's really the same thing deep down, but drivers should never care
about a kobject, just 'struct device'.  Well, even then it usually
should care about it's type of 'struct device' but that's a different
issue...

Anyway, not saying your patch is wrong at all, just for the future if
people are looking for code cleanups...

thanks,

greg k-h
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