Kirkwood issues with 3.8-rc1 - Ooops and hang on reboot

[Andrew Lunn]

On 03/01/13 05:50, Josh Coombs wrote:
> On Sat, Dec 29, 2012 at 7:23 PM, Russell King - ARM Linux
> <linux at arm.linux.org.uk>  wrote:
>> On Sat, Dec 29, 2012 at 06:31:37PM -0500, Josh Coombs wrote:
>>> Bah, didn't send to everyone last time...
>>>
>>> Building with CONFIG_DEBUG_SECTION_MISMATCH enabled, the only warning
>>> I get is for drivers/w1/masters/w1-gpio.o.
>>>
>>> WARNING: drivers/w1/masters/w1-gpio.o(.data+0x0): Section mismatch in
>>> reference from the variable w1_gpio_driver to the function
>>> .init.text:w1_gpio_probe()
>>> The variable w1_gpio_driver references
>>> the function __init w1_gpio_probe()
>>> If the reference is valid then annotate the
>>> variable with __init* or __refdata (see linux/init.h) or name the variable:
>>> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
>>>
>>> Shouldn't I be seeing a warning for
>>> drivers/clk/mvebu/clk-gating-ctrl.o at this point as well?
>>
>> Unfortunately not.  mvebu_clk_gating_get_src() is referenced by another
>> __init function, which is registering the pointer to
>> mvebu_clk_gating_get_src() into other code.  That reference (obviously
>> from the oops dump) persists past the point where the __init sections
>> are freed.
>>
>> Hence why no section mismatch warning issued from the static tools;
>> they're not infallible.
>
> Ok, so a workaround would be to remove the __init tag so persists
> properly, but it sounds like what I really should do is to find out
> where that other reference is and why it's persisting to make sure
> that's the right behavior in the first place?

Hi Josh

If you look in drivers/clk/mvebu/clk-gating-ctrl.c, 
mvebu_clk_gating_get_src() is passed as a parameter to 
of_clk_add_provider(). of_clk_add_provider() allocates a structure with 
kzalloc() and then assigns the function pointer to a member of the 
structure.

Because mvebu_clk_gateing_src() is passed as a parameter, the section 
missmatch checks cannot detect a problem. As far as i understand, its 
the linker which is checking for section miss matches. However, the 
linker is not involved here, its not a function calling a function, its 
a function passed to a function, and later a function called via a 
function pointer.

As far as i can see, the only error here is the wrong __init tag.

     Andrew