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Date:   Wed, 5 Aug 2020 11:11:05 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Chengming Zhou <zhouchengming@bytedance.com>,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [External] linux-next: build warning after merge of the ftrace
 tree
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On Wed, 5 Aug 2020 12:53:39 +0800
Muchun Song <songmuchun@bytedance.com> wrote:

> On Wed, Aug 5, 2020 at 12:21 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >
> > Hi all,
> >
> > After merging the ftrace tree, today's linux-next build (powerpc
> > ppc64_defconfig) produced this warning:
> >
> > kernel/kprobes.c: In function 'kill_kprobe':
> > kernel/kprobes.c:1116:33: warning: statement with no effect [-Wunused-value]
> >  1116 | #define disarm_kprobe_ftrace(p) (-ENODEV)
> >       |                                 ^
> > kernel/kprobes.c:2154:3: note: in expansion of macro 'disarm_kprobe_ftrace'
> >  2154 |   disarm_kprobe_ftrace(p);
> >       |   ^~~~~~~~~~~~~~~~~~~~
> >  
> 
> Sorry, maybe we should rework the macro of disarm_kprobe_ftrace to an
> inline function like below.
> 
> -#define disarm_kprobe_ftrace(p)        (-ENODEV)
> +static inline int disarm_kprobe_ftrace(struct kprobe *p)
> +{
> +       return -ENODEV
> +}
>  #endif

Looks like that would work. Care to send a formal patch. Could you also
change arm_kprobe_ftrace() as well?

Thanks!

-- Steve