linux-kernel - Re: [PATCH] m68k: atari: Make Atari ROM port I/O write macros return void

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Date:   Sat, 21 May 2022 09:44:02 +1200
From:   Michael Schmitz <schmitzmic@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org
Cc:     linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] m68k: atari: Make Atari ROM port I/O write macros return
 void

Hi Guenter,

I wish I knew of a way to fix this mess for good... suggestions would be 
welcome.

Looks like you spotted the last remaining macros without a void cast 
here, thanks.

FWIW:
Reviewed-by: Michael Schmitz <schmitzmic@...il.com>


Am 21.05.2022 um 02:52 schrieb Guenter Roeck:
> On 5/20/22 07:32, Geert Uytterhoeven wrote:
>> The macros implementing Atari ROM port I/O writes do not cast away their
>> output, unlike similar implementations for other I/O buses.
>> When they are combined using conditional expressions in the
>> definitions of
>> outb() and friends, this triggers sparse warnings like:
>>
>>      drivers/net/appletalk/cops.c:382:17: error: incompatible types in
>> conditional expression (different base types):
>>      drivers/net/appletalk/cops.c:382:17:    unsigned char
>>      drivers/net/appletalk/cops.c:382:17:    void
>>
>> Fix this by adding casts to "void".
>>
>> Reported-by: kernel test robot <lkp@...el.com>
>> Reported-by: Guenter Roeck <linux@...ck-us.net>
>> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>
>> ---
>> Survived m68k/allmodconfig.
>> To be queued in the m68k tree for v5.19.
>>
>> Removing the casts instead causes issues with functions propagating void
>> return values (return expression in void function), which BTW sparse
>> complains about, too.
>
> We live and learn. I didn't even know that this was valid syntax.
> I thought it might be easier to just fix that code, but coccinelle
> reports that there are hundreds of places in the kernel where this
> is done. Outch.
>
> Guenter