large frame size warning when compiling

[pauldaviesc@gmail.com (Paul Davies C)]

On Friday 09 May 2014 05:43 PM, Jay Aurabind wrote:
> On Thu, May 08, 2014 at 02:38:24PM +0200, Martin Kepplinger wrote:
>> Am 2014-05-07 18:36, schrieb Jay Aurabind:
>>> Hello list, Time for a noob discussion,
>>>
>>> When I was building the kernel, I found a warning from drivers/mfd/abx500-core.c, that the Frame size is larger than 1024 bytes. Apparently the stack frame size can be changed from the config, but my question is, whether 1024 bytes low ? I am on an x86_64 (core i3).
>>>
>>> abx500-core.c had an object of struct device being allocated on stack. So
>>> dynamically allocating it makes the warning go away. Are there any
>>> implications on using dynamic allocation on this particular code? I
>>> mean, could there be some reason why the original developer went with static option ?
>> kmalloc may sleep and is therefore sometimes not recommended to be used.
>>
> Sure, but this code doesnt appear to be holding any locks. So it should
> be okay to call kmalloc here I guess.
You can use kmalloc even if you are holding a lock. Care must be taken 
to pass GFP_ATOMIC flag to the kmalloc, so that it does not sleep.
>>>
>>> ---
>>>   drivers/mfd/abx500-core.c | 8 +++++---
>>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/mfd/abx500-core.c b/drivers/mfd/abx500-core.c
>>> index f3a15aa..709a84f 100644
>>> --- a/drivers/mfd/abx500-core.c
>>> +++ b/drivers/mfd/abx500-core.c
>>> @@ -154,15 +154,17 @@ EXPORT_SYMBOL(abx500_startup_irq_enabled);
>>>   void abx500_dump_all_banks(void)
>>>   {
>>>   	struct abx500_ops *ops;
>>> -	struct device dummy_child = {NULL};
>>> +	struct device *dummy_child;
>>>   	struct abx500_device_entry *dev_entry;
>>>   
>>> +	dummy_child = kzalloc(sizeof(struct device),GFP_KERNEL);
>>> +
>>>   	list_for_each_entry(dev_entry, &abx500_list, list) {
>>> -		dummy_child.parent = dev_entry->dev;
>>> +		dummy_child->parent = dev_entry->dev;
>>>   		ops = &dev_entry->ops;
>>>   
>>>   		if ((ops != NULL) && (ops->dump_all_banks != NULL))
>>> -			ops->dump_all_banks(&dummy_child);
>>> +			ops->dump_all_banks(dummy_child);
>>>   	}
>>>   }
>>>   EXPORT_SYMBOL(abx500_dump_all_banks);
>>>
>>>
>>>
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-- 
Paul Davies C,
CSE B.Tech. student,
Govt. Engineering College, Thrissur.