linux-kernel - Re: [PATCH v2 2/2] io: prevent compiler reordering on the default readX() implementation

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Date:   Wed, 4 Apr 2018 11:57:34 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Palmer Dabbelt <palmer@...ive.com>,
        Mark Rutland <mark.rutland@....com>,
        Timur Tabi <timur@...eaurora.org>, sulrich@...eaurora.org,
        linux-arm-msm@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] io: prevent compiler reordering on the default
 readX() implementation

On 4/4/2018 11:55 AM, Arnd Bergmann wrote:
> On Wed, Apr 4, 2018 at 5:52 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
>> On 4/3/2018 6:29 PM, Palmer Dabbelt wrote:
>>>
>>
>> Are we looking for something like this?
> 
> Yes, exactly, plus the same for write and in/out of course.
> 

OK. I just wanted to double check first.

>> diff --git a/inc
>>  #ifndef readb
>>  #define readb readb
>> -static inline u8 readb(const volatile void __iomem *addr)
>> -{
>> -       return __raw_readb(addr);
>> -}
>> +#define readb(c)                               \
>> +       ({ u8  __v;                             \
>> +        __io_br();                             \
>> +        __v = __raw_readb(c);                  \
>> +        __io_ar();                             \
>> +        __v; })
>>  #endif
> 
> I would prefer leaving these as inline functions, but that's only
> a cosmetic difference.

sure, I'll leave these as inline functions.

> 
>        Arnd
> 


-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.