Re: [PATCH 3/5] ACPI, APEI, HEST Fix the unsuitable usage of platform_data

[Jin Dongming <jin.dongming@np.css.fujitsu.com>]

Hi, Andi
(2010/09/21 21:43), Andi Kleen wrote:
> On Sun, Sep 19, 2010 at 11:00:33AM +0800, Huang Ying wrote:
>> diff --git a/drivers/acpi/apei/hest.c b/drivers/acpi/apei/hest.c
>> index 343168d..1a3508a 100644
>> --- a/drivers/acpi/apei/hest.c
>> +++ b/drivers/acpi/apei/hest.c
>> @@ -137,20 +137,23 @@ static int hest_parse_ghes_count(struct acpi_hest_header *hest_hdr, void *data)
>>  
>>  static int hest_parse_ghes(struct acpi_hest_header *hest_hdr, void *data)
> 
> hest_hdr is a local variable on the stack.
> 
Yes, you are right. Exactly what hest_hdr pointed is ghes address of 
global static variable hest_tab.
> 
>> +
>> +	rc = platform_device_add_data(ghes_dev, &hest_hdr, sizeof(void *));
>> +	if (rc)
>> +		goto err;
> 
> Now you put the address of that local variable in some global data structure.
> 
> And then you likely return and later the access accesses random stack space? 
> 
No, I don't think so.

Here the value(ghes address) of hest_hdr is saved into the private area of ghes_dev,
not the address of hest_hdr itself. So what you described will not happen.

Best Regards,
Jin Dongming

> -Andi
> 
>