Subject: Re: [v4] Fix to avoid IS_ERR_VALUE and IS_ERR abuses on 64bit systems.

From: arvind Yadav <[email-masked]>
Date: Tue, 2 Aug 2016 21:04:38 +0530

On Tuesday 02 August 2016 01:15 PM, Arnd Bergmann wrote:
> On Monday, August 1, 2016 4:55:43 PM CEST Scott Wood wrote:
>> On 08/01/2016 02:02 AM, Arnd Bergmann wrote:
>>>> diff --git a/include/linux/err.h b/include/linux/err.h
>>>> index 1e35588..c2a2789 100644
>>>> --- a/include/linux/err.h
>>>> +++ b/include/linux/err.h
>>>> @@ -18,7 +18,17 @@
>>>>   
>>>>   #ifndef __ASSEMBLY__
>>>>   
>>>> -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
>>>> +#define IS_ERR_VALUE(x) unlikely(is_error_check(x))
>>>> +
>>>> +static inline int is_error_check(unsigned long error)
>>> Please leave the existing macro alone. I think you were looking for
>>> something specific to the return code of qe_muram_alloc() function,
>>> so please add a helper in that subsystem if you need it, not in
>>> the generic header files.
>> qe_muram_alloc (a.k.a. cpm_muram_alloc) returns unsigned long.  The
>> problem is certain callers that store the return value in a u32.  Why
>> not just fix those callers to store it in unsigned long (at least until
>> error checking is done)?
>>
> Yes, that would also address another problem with code like
>
>           kfree((void *)ugeth->tx_bd_ring_offset[i]);
>
> which is not 64-bit safe when tx_bd_ring_offset is a 32-bit value
> that also holds the return value of qe_muram_alloc.
>
> 	Arnd
Yes, we will fix caller. Caller api is not safe on 64bit.
Even qe_muram_addr(a.k.a. cpm_muram_addr )passing value unsigned int,
but it should be unsigned long.