netdev - Re: [PATCH net-next] net: sched: remove redundant NULL check in change hook function

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Date:   Mon, 29 Aug 2022 15:00:55 +0800
From:   shaozhengchao <shaozhengchao@...wei.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <toke@...e.dk>, <jhs@...atatu.com>, <jiri@...nulli.us>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <stephen@...workplumber.org>,
        <cake@...ts.bufferbloat.net>, <weiyongjun1@...wei.com>,
        <yuehaibing@...wei.com>
Subject: Re: [PATCH net-next] net: sched: remove redundant NULL check in
 change hook function



On 2022/8/29 13:36, Cong Wang wrote:
> On Sat, Aug 27, 2022 at 09:49:10AM +0800, Zhengchao Shao wrote:
>> Currently, the change function can be called by two ways. The one way is
>> that qdisc_change() will call it. Before calling change function,
>> qdisc_change() ensures tca[TCA_OPTIONS] is not empty. The other way is
>> that .init() will call it. The opt parameter is also checked before
>> calling change function in .init(). Therefore, it's no need to check the
>> input parameter opt in change function.
>>
> 
> Right.. but the one below:
> 
>> diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
>> index c50a0853dcb9..e23d3dbb7272 100644
>> --- a/net/sched/sch_gred.c
>> +++ b/net/sched/sch_gred.c
>> @@ -413,9 +413,6 @@ static int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps,
>>   	bool red_flags_changed;
>>   	int i;
>>   
>> -	if (!dps)
>> -		return -EINVAL;
>> -
> 
> I don't think anyone checks tb[TCA_GRED_DPS]. What you intended to patch
> is gred_change(), right?
> 
> Thanks.

Hi Wang:
	Thank you for your reply. You are right. I will send v2.

Zhengchao Shao