Re: [PATCH v3 1/2] tty: add compat_ioctl callbacks

[Aleksa Sarai <asarai@suse.de>]

>> diff --git a/Makefile b/Makefile
>> index 470bd4d9513a..fb689286d83a 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -401,6 +401,7 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
>>                     -fno-strict-aliasing -fno-common \
>>                     -Werror-implicit-function-declaration \
>>                     -Wno-format-security \
>> +                  -Wno-error=int-in-bool-context \
>>                     -std=gnu89 $(call cc-option,-fno-PIE)
> 
> This  slipped in by accident I assume? It seems completely unrelated.

Yeah, I re-sent v4 with this removed immediately afterwards.

> 
>> diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
>> index 65799575c666..2a6bd9ae3f8b 100644
>> --- a/drivers/tty/pty.c
>> +++ b/drivers/tty/pty.c
>> @@ -481,6 +481,16 @@ static int pty_bsd_ioctl(struct tty_struct *tty,
>>          return -ENOIOCTLCMD;
>>   }
>>
>> +static long pty_bsd_compat_ioctl(struct tty_struct *tty,
>> +                                unsigned int cmd, unsigned long arg)
>> +{
>> +       /*
>> +        * PTY ioctls don't require any special translation between 32-bit and
>> +        * 64-bit userspace, they are already compatible.
>> +        */
>> +       return pty_bsd_ioctl(tty, cmd, arg);
>> +}
>> +
> 
> This looks correct but unnecessary, you can simply point both
> function pointers to the same function:

They have different types, since they have different return types:

int  (*ioctl)(struct tty_struct *tty,
	    unsigned int cmd, unsigned long arg);
long (*compat_ioctl)(struct tty_struct *tty,
		     unsigned int cmd, unsigned long arg);

If you like, I can change (*ioctl) to return longs as well, and then 
change all of the call-sites (since unlocked_ioctl also returns long).

-- 
Aleksa Sarai
Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/