Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220917071427.28499-1-akinobu.mita@gmail.com> <93c044ca-7d2f-e23f-8eb4-72c133737a15@redhat.com>
In-Reply-To: <93c044ca-7d2f-e23f-8eb4-72c133737a15@redhat.com>
From:   Akinobu Mita <akinobu.mita@gmail.com>
Date:   Mon, 19 Sep 2022 20:40:38 +0900
Message-ID: <CAC5umyhhnoJvoGT5NQX8VNn4QT_3qA1nY5tnZre59pL7vbMpzg@mail.gmail.com>
Subject: Re: [PATCH -v2] lib/notifier-error-inject: fix error when writing
 errno to debugfs file
To:     David Hildenbrand <david@redhat.com>
Cc:     linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>, osalvador@suse.de,
        shuah@kernel.org, Zhao Gongyi <zhaogongyi@huawei.com>,
        Wei Yongjun <weiyongjun1@huawei.com>,
        Yicong Yang <yangyicong@hisilicon.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

2022=E5=B9=B49=E6=9C=8819=E6=97=A5(=E6=9C=88) 18:20 David Hildenbrand <davi=
d@redhat.com>:
>
> On 17.09.22 09:14, Akinobu Mita wrote:
> > The simple attribute files do not accept a negative value since the
> > commit 488dac0c9237 ("libfs: fix error cast of negative value in
> > simple_attr_write()"), so we can no longer use DEFINE_SIMPLE_ATTRIBUTE(=
) to
> > define a file operations for errno value.
> >
> > Fixes: 488dac0c9237 ("libfs: fix error cast of negative value in simple=
_attr_write()")
> > Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
>
> But shouldn't we fix simple_attr_write() instead?
>
> I mean, simple_attr_read() might use attr->fmt to print a signed value,
> but simple_attr_write() fails on signed values now?
>
> I might be wrong, but there is a disconnect. I feel like
> simple_attr_write() should similarly make decisions based on attr->fmt.

I agree there is a disconnect, but I have no idea how to fix
simple_attr_write().
(strcmp(attr->fmt, "%%lld\n") is ugly)
If no one seems to come up with a good idea, I'll fix the similar problems
in fault-injection the same way I did here.