netdev - Re: [v3] UCC_GETH/UCC_FAST: Use IS_ERR_VALUE_U32 API to avoid IS_ERR

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Message-ID: <5798EA36.70000@gmail.com>
Date:	Wed, 27 Jul 2016 22:37:02 +0530
From:	arvind Yadav <arvind.yadav.cs@...il.com>
To:	Arnd Bergmann <arnd@...db.de>, linuxppc-dev@...ts.ozlabs.org
Cc:	zajec5@...il.com, leoli@...escale.com, qiang.zhao@...escale.com,
	viresh.kumar@...aro.org, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, scottwood@...escale.com,
	akpm@...ux-foundation.org, linux@...ck-us.net
Subject: Re: [v3] UCC_GETH/UCC_FAST: Use IS_ERR_VALUE_U32 API to avoid
 IS_ERR_VALUE abuses.

I am also agree with Arnd Bergmann. We should use 'static inline function'
instead of macro to deal with error check.

On Tuesday 26 July 2016 05:09 PM, Arnd Bergmann wrote:
> On Saturday, July 23, 2016 11:35:51 PM CEST Arvind Yadav wrote:
>> diff --git a/include/linux/err.h b/include/linux/err.h
>> index 1e35588..a42f942 100644
>> --- a/include/linux/err.h
>> +++ b/include/linux/err.h
>> @@ -19,6 +19,7 @@
>>   #ifndef __ASSEMBLY__
>>   
>>   #define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
>> +#define IS_ERR_VALUE_U32(x) unlikely((unsigned int)(x) >= (unsigned int)-MAX_ERRNO)
>>   
>>   static inline void * __must_check ERR_PTR(long error)
>>   {
> This doesn't really look like something we want to have as a generic
> interface. The IS_ERR_VALUE() API is rather awkward already, and your
> use seems specific to the cpu_muram_alloc() function.
>
> How about something like
>
> int cpm_muram_error(unsigned long addr)
> {
> 	if (addr >= (unsigned long)-MAX_ERRNO)
> 		return addr;
> 	else
> 		return 0;
> }
>
> and then use that to check the value returned by the allocation
> that is still an 'unsigned long', before assigning it to a 'u32'.
>
> 	Arnd