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From:   Alexey Dobriyan <adobriyan@gmail.com>
Date:   Thu, 22 Nov 2018 13:40:41 +0200
Message-ID: <CACVxJT9ns2XGeE3FUwNT2J2Fn2s0YuHPQT-z6yg2RE8qzK-ssQ@mail.gmail.com>
Subject: Re: [PATCH] procfs: fix the output format in /proc/PID/wchan
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Yafang Shao <laoar.shao@gmail.com>, viro@zeniv.linux.org.uk,
        keescook@chromium.org, orcunov@openvz.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
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On Wed, Nov 21, 2018 at 07:28:44PM -0800, Andrew Morton wrote:
> On Mon, 19 Nov 2018 19:17:52 +0800 Yafang Shao <laoar.shao@gmail.com> wrote:
>
> > Just add the missing newline.
> >
> > ...
> >
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -370,11 +370,12 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
> >  	wchan = get_wchan(task);
> >  	if (wchan && !lookup_symbol_name(wchan, symname)) {
> >  		seq_puts(m, symname);
> > +		seq_putc(m, '\n');
> >  		return 0;
> >  	}
> >
> >  print0:
> > -	seq_putc(m, '0');
> > +	seq_puts(m, "0\n");
> >  	return 0;
> >  }
> >  #endif /* CONFIG_KALLSYMS */
>
> What is presently wrong with the wchan output?  The changelog
> should explain such things, please.

It is just newline to make "cat /proc/*/wchan" output look cool.
But newline can break something.