linux-kernel - Re: [PATCH v3 3/4] hugetlb: Fix return value of _

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Message-ID: <b6920f9f-4a0d-ec51-9f88-9fb3012a05d1@huawei.com>
Date:   Wed, 13 Apr 2022 16:45:30 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Muchun Song <songmuchun@...edance.com>,
        "liupeng (DM)" <liupeng256@...wei.com>
CC:     <mike.kravetz@...cle.com>, <david@...hat.com>,
        <akpm@...ux-foundation.org>, <yaozhenguo1@...il.com>,
        <baolin.wang@...ux.alibaba.com>, <liuyuntao10@...wei.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/4] hugetlb: Fix return value of __setup handlers


On 2022/4/13 16:21, Muchun Song wrote:
> On Wed, Apr 13, 2022 at 04:16:11PM +0800, liupeng (DM) wrote:
>> On 2022/4/13 15:55, Muchun Song wrote:
>>> On Wed, Apr 13, 2022 at 03:29:14AM +0000, Peng Liu wrote:
>>>> When __setup() return '0', using invalid option values causes the
>>>> entire kernel boot option string to be reported as Unknown. Hugetlb
>>>> calls __setup() and will return '0' when set invalid parameter
>>>> string.
>>>>
>>>> The following phenomenon is observed:
>>>>    cmdline:
>>>>     hugepagesz=1Y hugepages=1
>>>>    dmesg:
>>>>     HugeTLB: unsupported hugepagesz=1Y
>>>>     HugeTLB: hugepages=1 does not follow a valid hugepagesz, ignoring
>>>>     Unknown kernel command line parameters "hugepagesz=1Y hugepages=1"
>>>>
>>>> Since hugetlb will print warning/error information before return for
>>>> invalid parameter string, just use return '1' to avoid print again.
>>>>
>>> Can't return -EINVAL? It is weird to return 1 on failure.
>>>
>>> Thanks.
>>>
>>> .
>> Not against "return -EINVAL", but consistent with:
>> 1d02b444b8d1 ("tracing: Fix return value of __setup handlers")
> I think it is better not return 1.  I don't think it's a good habit we
> should follow.
/*
  * NOTE: __setup functions return values:
  * @fn returns 1 (or non-zero) if the option argument is "handled"
  * and returns 0 if the option argument is "not handled".
  */
#define __setup(str, fn)               \
        __setup_param(str, fn, fn, 0)


1 or -EINVAL should ok, and  most __setup return 1 for know ;)

> Thanks.
>
> Thanks.
>
> .