Re: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue

From: Khalid Masum <khalid.masum.92@gmail.com>
To: Siddh Raman Pant <code@siddh.me>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	"syzbot+c70d87ac1d001f29a058" 
	<syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com>,
	linux-kernel-mentees 
	<linux-kernel-mentees@lists.linuxfoundation.org>,
	linux-security-modules <linux-security-module@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	"Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: Re: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue
Date: Sun, 24 Jul 2022 09:45:27 +0600	[thread overview]
Message-ID: <CAABMjtEHCy=YcfqYfsQdqt9pWHHRoOLYHiRCsj8HjZVfAOB+6A@mail.gmail.com> (raw)
In-Reply-To: <1822b76775c.69c52873236056.4849193904753307696@siddh.me>

On Sat, Jul 23, 2022 at 8:29 PM Siddh Raman Pant via
Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>
wrote:
>
> On Sat, 23 Jul 2022 19:33:33 +0530  Greg KH <gregkh@linuxfoundation.org> wrote:
> > You should not use #ifdef in .c files, it's unmaintainable over time.
> >
> > thanks,
> >
> > greg k-h
> >
>
> I used it because it is used in the same way in fs/pipe.c too (please check the
> stated line number).
>
> That, in turn, is because `watch_queue` member in the `pipe_inode_info` struct
> is defined that way (see line 80 of include/linux/pipe_fs_i.h), so I am forced
> to use the ifdef guard.
>
Maybe, we can use the IS_ENABLED macro here to avoid ifdef in the .c file as
suggested here:
https://www.kernel.org/doc/html/v4.10/process/coding-style.html#conditional-compilation

if(IS_ENABLED(CONFIG_WATCH_QUEUE)){
     ...
}

> Thanks,
> Siddh

Thanks,
  -- Khalid Masum