Re: [PATCH v7 45/50] drivers/of: Avoid recursively calling unflatten_dt_node()

Guenter Roeck
2015-12-06T21:49:36Z

On 12/06/2015 12:28 PM, Rob Herring wrote:
> +Guenter
>
> On Wed, Nov 4, 2015 at 7:12 AM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
>> In current implementation, unflatten_dt_node() is called recursively
>> to unflatten device nodes in FDT blob. It's stress to limited stack
>> capacity.
>>
>> This avoids calling the function recursively, meaning the device
>> nodes are unflattened in one call on unflatten_dt_node(): two arrays
>> are introduced to track the parent path size and the device node of
>> current level of depth, which will be used by the device node on next
>> level of depth to be unflattened. Also, the parameter "poffset" and
>> "fpsize" are unused and dropped.
>
> Do you plan to respin the OF parts at least soon? There's another
> problem Guenter found that of_fdt_unflatten_tree is not re-entrant due
> to "depth" being static and this series fixes that. So I'd rather
> apply this and avoid adding a mutex if possible.
>

Hi Rob,

We see this problem in 4.1, so whatever patch you accept should be
back-ported to at least that release.

Any idea when this patch will be accepted ? We actively see the problem
in our kernel, so I'll need a solution soon. Otherwise I'll have to apply
my patch to our kernel and revert it as soon as the 'real' patch has been
back-ported.

Thanks,
Guenter