Re: [PATCH] power: Change device_wakeup_enable() to check for nulldev_name(dev)

From: Shuah Khan
Date: Sat Nov 16 2013 - 10:29:14 EST


On 11/15/2013 05:25 PM, Greg KH wrote:
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...


Use of kobject_set_name() did look odd to me. I will fix that for this driver by re-doing the patch while I am it. About the power_supply patch, stable needs fixing as well, and I will have to backport once he fix goes into the mainline.

http://www.kernelhub.org/?msg=362354&p=2 as is doesn't apply to 3.10 and 3.11

-- Shuah

--
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@xxxxxxxxxxx | (970) 672-0658
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