linux-kernel - Re: [PATCH] LoongArch: Delete debugfs checking

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Message-ID: <CAAhV-H6EisP3BLAPb64To=bX-S-XaPwHmxRB1BpU+YP4McMyzg@mail.gmail.com>
Date:   Wed, 28 Jun 2023 23:37:13 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     WANG Xuerui <kernel@...0n.name>
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        Ivan Orlov <ivan.orlov0322@...il.com>,
        Immad Mir <mirimmad17@...il.com>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] LoongArch: Delete debugfs checking

Queued for loongarch-next, thanks.


Huacai

On Wed, Jun 28, 2023 at 10:22 PM WANG Xuerui <kernel@...0n.name> wrote:
>
> Hi,
>
> On 2023/6/20 16:06, Dan Carpenter wrote:
> > Debugfs functions are not supposed to be checked for errors.  This
> > is sort of unusual but it is described in the comments for the
> > debugfs_create_dir() function.  Also debugfs_create_dir() can never
> > return NULL.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> > I spotted this code because I was looking at patches which were sent
> > to stable but without a Fixes tag.  The correct way of checking for
> > error pointers is not IS_ERR_OR_NULL(), it's IS_ERR().  When a function
> > returns both error pointers and NULL, the NULL should be treated as a
> > special kind of success.  Please see my blog for more details.
> >
> > https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/
> >
> > I have not included a Fixes tag here, because it's not really a bug fix,
> > it's just a clean up.
>
> Thanks for the patch and sorry for the late review. I didn't notice this
> back then (just recovering from covid around that time) but since
> loongarch-next isn't tagged yet I think the patch could make it this
> cycle. (Somehow Huacai didn't see the mail either, weird...)
>
> >
> >   arch/loongarch/kernel/unaligned.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/arch/loongarch/kernel/unaligned.c b/arch/loongarch/kernel/unaligned.c
> > index 85fae3d2d71a..3abf163dda05 100644
> > --- a/arch/loongarch/kernel/unaligned.c
> > +++ b/arch/loongarch/kernel/unaligned.c
> > @@ -485,8 +485,6 @@ static int __init debugfs_unaligned(void)
> >       struct dentry *d;
> >
> >       d = debugfs_create_dir("loongarch", NULL);
> > -     if (IS_ERR_OR_NULL(d))
> > -             return -ENOMEM;
> >
> >       debugfs_create_u32("unaligned_instructions_user",
> >                               S_IRUGO, d, &unaligned_instructions_user);
>
> Trivial enough, thanks!
>
> Reviewed-by: WANG Xuerui <git@...0n.name>
>
> --
> WANG "xen0n" Xuerui
>
> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
>
>