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Message-ID: <2a07bded-25e5-fd27-a2de-8b606e4d1d2c@I-love.SAKURA.ne.jp>
Date:   Sat, 29 Apr 2023 19:43:47 +0900
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Subject: Re: [PATCH] tty: tty_io: remove hung_up_tty_fops
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To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        syzbot <syzbot+b7c3ba8cdc2f6cf83c21@syzkaller.appspotmail.com>,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
References: <20230423233433.GF3390869@ZenIV>
 <e1fe6a44-3021-62ad-690a-69146e39e1ac@I-love.SAKURA.ne.jp>
 <20230424004431.GG3390869@ZenIV>
 <8e21256a-736e-4c2d-1ff4-723775bcac46@I-love.SAKURA.ne.jp>
 <2fca7932-5030-32c3-dd61-48dd78e58e11@I-love.SAKURA.ne.jp>
 <20230425160344.GS3390869@ZenIV>
 <1b405689-ea0a-6696-6709-d372ce72d68c@I-love.SAKURA.ne.jp>
 <5cebade5-0aa9-506c-c817-7bcf098eba89@I-love.SAKURA.ne.jp>
 <20230428162718.GA1099174@dev-arch.thelio-3990X>
 <6dca757e-74ac-773d-2a50-4e48b2f56880@I-love.SAKURA.ne.jp>
 <20230428171145.GD3390869@ZenIV>
From:   Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
In-Reply-To: <20230428171145.GD3390869@ZenIV>
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On 2023/04/29 2:11, Al Viro wrote:
> On Sat, Apr 29, 2023 at 01:41:02AM +0900, Tetsuo Handa wrote:
>> On 2023/04/29 1:27, Nathan Chancellor wrote:
>>> I see this change has shown up in -next as commit 4c87e9e5479b ("tty:
>>> tty_io: remove hung_up_tty_fops"), where it causes the following warning
>>> for configurations without CONFIG_COMPAT (I used ARCH=arm defconfig):
>>>
>>>   drivers/tty/tty_io.c:446:13: warning: 'hung_up_tty_compat_ioctl' defined but not used [-Wunused-function]
>>>     446 | static long hung_up_tty_compat_ioctl(struct file *file,
>>>         |             ^~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> I am not sure if you just added that patch for additional test coverage
>>> or for final acceptance but the following diff resolves this warning for
>>> me, perhaps it can be folded in for a v2?
>>
>> Thank you for reporting. Yes, moving the definition will solve the warning.
> 
> 	IDGI...  Why do you need to keep that function at all?  Compare it
> with hung_up_tty_ioctl() - they are token-for-token identical; the only
> difference is the function name...

Indeed hung_up_tty_ioctl() and hung_up_tty_compat_ioctl() are identical.
We can remove hung_up_tty_compat_ioctl() if we don't consider

 	ld = tty_ldisc_ref_wait(tty);
 	if (!ld)
-		return hung_up_tty_compat_ioctl(file, cmd, arg);
+		return hung_up_tty_ioctl(file, cmd, arg);
 	if (ld->ops->compat_ioctl)
 		retval = ld->ops->compat_ioctl(tty, cmd, arg);

at tty_compat_ioctl() as strange looking.

Maybe adding "inline" keyword to hung_up_tty_*() definitions
because hung_up_tty_fops is removed?