linux-kernel - Re: [PATCH V1 1/2] mm/damon/sysfs: avoid call damon_target_has

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Message-ID: <11a3021e-860b-e00e-8289-45831feed2e4@linux.alibaba.com>
Date:   Fri, 16 Sep 2022 16:57:27 +0800
From:   haoxin <xhao@...ux.alibaba.com>
To:     SeongJae Park <sj@...nel.org>
Cc:     akpm@...ux-foundation.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V1 1/2] mm/damon/sysfs: avoid call damon_target_has_pid()
 repeatedly


在 2022/9/16 下午4:42, SeongJae Park 写道:
> On Thu, 15 Sep 2022 22:22:36 +0800 Xin Hao <xhao@...ux.alibaba.com> wrote:
>
>> In damon_sysfs_destroy_targets(), we call damon_target_has_pid() to
>> check whether the 'ctx' include a valid pid, but there no need to call
>> damon_target_has_pid() to check repeatedly, just need call it once.
> Good eyes, nice finding!
>
>> Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
>> ---
>>   mm/damon/sysfs.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
>> index 1fa0023f136e..966ea7892ccf 100644
>> --- a/mm/damon/sysfs.c
>> +++ b/mm/damon/sysfs.c
>> @@ -2143,9 +2143,13 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
>>   static void damon_sysfs_destroy_targets(struct damon_ctx *ctx)
>>   {
>>   	struct damon_target *t, *next;
>> +	bool has_pid = false;
>> +
>> +	if (damon_target_has_pid(ctx))
>> +		has_pid = true;
> How about doing more simple and short like below?
>
>      bool has_pid = damon_target_has_pid(ctx)
Yes, Do like this, make code look more clean. but this patch has been 
merged into,  i send a new one to fix it ?
>
> Other than this,
>
> Reviewed-by: SeongJae Park <sj@...nel.org>
>
>
> Thanks,
> SJ
>
>>   	damon_for_each_target_safe(t, next, ctx) {
>> -		if (damon_target_has_pid(ctx))
>> +		if (has_pid)
>>   			put_pid(t->pid);
>>   		damon_destroy_target(t);
>>   	}
>> --
>> 2.31.0