linux-kernel - Re: [PATCH 27/33] sched/debug: use match

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Message-ID: <8a7108ce-a109-a1b5-ace7-38a189d2352d@huawei.com>
Date:   Tue, 22 May 2018 20:10:37 +0800
From:   Yisheng Xie <xieyisheng1@...wei.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 27/33] sched/debug: use match_string() helper

Hi Andy,

On 2018/5/22 6:13, Andy Shevchenko wrote:
> On Mon, May 21, 2018 at 2:58 PM, Yisheng Xie <xieyisheng1@...wei.com> wrote:
>> match_string() returns the index of an array for a matching string,
>> which can be used intead of open coded variant.
>>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
>> ---
>>  kernel/sched/debug.c | 20 +++++++++-----------
>>  1 file changed, 9 insertions(+), 11 deletions(-)
>>
>> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
>> index 15b10e2..9e34499 100644
>> --- a/kernel/sched/debug.c
>> +++ b/kernel/sched/debug.c
>> @@ -111,16 +111,14 @@ static int sched_feat_set(char *cmp)
>>                 cmp += 3;
>>         }
>>
>> -       for (i = 0; i < __SCHED_FEAT_NR; i++) {
>> -               if (strcmp(cmp, sched_feat_names[i]) == 0) {
>> -                       if (neg) {
>> -                               sysctl_sched_features &= ~(1UL << i);
>> -                               sched_feat_disable(i);
>> -                       } else {
>> -                               sysctl_sched_features |= (1UL << i);
>> -                               sched_feat_enable(i);
>> -                       }
>> -                       break;
>> +       i = match_string(sched_feat_names, __SCHED_FEAT_NR, cmp);
> 
>> +       if (i >= 0) {
> 
> Why not
> 
> if (i < 0)
>  return i;

if i >=0 it will also return i. so need return i just if (i < 0), right ?

> 
> ?
> 
>> +               if (neg) {
>> +                       sysctl_sched_features &= ~(1UL << i);
>> +                       sched_feat_disable(i);
>> +               } else {
>> +                       sysctl_sched_features |= (1UL << i);
>> +                       sched_feat_enable(i);
>>                 }
>>         }
>>
>> @@ -150,7 +148,7 @@ static int sched_feat_set(char *cmp)
>>         inode_lock(inode);
>>         i = sched_feat_set(cmp);
>>         inode_unlock(inode);
> 
>> -       if (i == __SCHED_FEAT_NR)
>> +       if (i < 0)
>>                 return -EINVAL;
> 
> Now it would be
> 
> if (i < 0)
>  return i;

Right, will change it in next version

Thanks
Yisheng Xie
>