linux-kernel - Re: [PATCH v3] tty: vt: keyboard: add default switch-case, to handle smatch-warnings in method vt_do_kdgkb

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Date:   Sun, 7 Nov 2021 01:25:54 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Ajay Garg <ajaygargnsit@...il.com>
Cc:     gregkh@...uxfoundation.org, jirislaby@...nel.org,
        andriy.shevchenko@...ux.intel.com, kernel@...il.dk,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] tty: vt: keyboard: add default switch-case, to handle
 smatch-warnings in method vt_do_kdgkb_ioctl

On 11/7/21 01:17, Ajay Garg wrote:
> On Sun, Nov 7, 2021 at 3:42 AM Pavel Skripkin <paskripkin@...il.com> wrote:
>>
>> On 11/7/21 01:03, Ajay Garg wrote:
>> > diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
>> > index c7fbbcdcc346..b83e7669658d 100644
>> > --- a/drivers/tty/vt/keyboard.c
>> > +++ b/drivers/tty/vt/keyboard.c
>> > @@ -2090,6 +2090,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
>> >
>> >               ret = 0;
>> >               break;
>> > +     default: {
>> > +             kbs = NULL;
>> > +             ret = -ENOIOCTLCMD;
>> > +
>> > +             break;
>> > +     }
>>
>> Are these brackets needed here? There are no local variables inside
>> default case.
> 
> Hmm,
> 
> * case KDGKBSENT: uses braces.
> * case KDSKBSENT: does not use braces.
> 
> I based the layout for default-case on the same lines as case
> KDGKBSENT: , as I prefer explicit braces :)
> 

I am not against these braces, but I, honestly, dislike them, because 
`case : {` syntax looks ugly _to me_.

KDGKBSENT uses it because of local variable `len` and not using them 
will cause build error.

I didn't find any strict requirements to not use brackets when there is 
no local variable, so it's up to maintainers (again).


Anyway, thank for respinning :)



With regards,
Pavel Skripkin