linux-kernel - Re: [PATCH v2 21/21] sparc64: use match

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Message-ID: <0eb48f06-2046-0b5e-4f16-4ebf3bd056b2@huawei.com>
Date:   Tue, 5 Jun 2018 17:05:27 +0800
From:   Yisheng Xie <xieyisheng1@...wei.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Anthony Yznaga <anthony.yznaga@...cle.com>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        <sparclinux@...r.kernel.org>
Subject: Re: [PATCH v2 21/21] sparc64: use match_string() helper

Hi Andy,

On 2018/6/4 18:06, Andy Shevchenko wrote:
> On Mon, Jun 4, 2018 at 4:06 AM, Yisheng Xie <xieyisheng1@...wei.com> wrote:
>> Hi Andy,
>>
>> On 2018/6/1 19:34, Andy Shevchenko wrote:
>>> On Thu, May 31, 2018 at 2:11 PM, Yisheng Xie <xieyisheng1@...wei.com> wrote:
>>>> match_string() returns the index of an array for a matching string,
>>>> which can be used instead of open coded variant.
>>>
>>>> @@ -512,10 +512,9 @@ static unsigned long __init mdesc_cpu_hwcap_list(void)
>>>>                                 break;
>>>>                         }
>>>>                 }
>>>
>>> It seems previous loop also can be replaced.
>>
>> No, because the there is an NULL in the middle of the array hwcaps:
>>  static const char *hwcaps[] = {
>>           "flush", "stbar", "swap", "muldiv", "v9",
>>           "ultra3", "blkinit", "n2",
>>
>>           /* These strings are as they appear in the machine description
>>            * 'hwcap-list' property for cpu nodes.
>>            */
>>           "mul32", "div32", "fsmuld", "v8plus", "popc", "vis", "vis2",
>>           "ASIBlkInit", "fmaf", "vis3", "hpc", "random", "trans", "fjfmau",
>>           "ima", "cspare", "pause", "cbcond", NULL /*reserved for crypto */,
>>           "adp",
>>   };
> 
> Actually you can.
> What you need is to add string literal instead of NULL and make an
> additional condition after match_string() in all users (not to many),
> something like
> 
> i = match_string();
> if (i < 0)
>  ...
> if (BIT(i) == HWCAP_SPARC_CRYPTO) // or !=

OK, I get your point.

Thanks
Yisheng
>  ...
>