linux-kernel - Re: [PATCH] kprobes: fix compiler warning for !CONFIG_KPROBES_ON

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Date:   Thu, 6 Aug 2020 10:30:35 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     rostedt@...dmis.org, naveen.n.rao@...ux.ibm.com,
        anil.s.keshavamurthy@...el.com, davem@...emloft.net,
        ast@...nel.org, daniel@...earbox.net, kafai@...com,
        songliubraving@...com, yhs@...com, andriin@...com,
        john.fastabend@...il.com, kpsingh@...omium.org,
        sfr@...b.auug.org.au, mingo@...nel.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH] kprobes: fix compiler warning for
 !CONFIG_KPROBES_ON_FTRACE

On Thu,  6 Aug 2020 01:20:46 +0800
Muchun Song <songmuchun@...edance.com> wrote:

> Fix compiler warning(as show below) for !CONFIG_KPROBES_ON_FTRACE.
> 
> 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);
> 
> Link: https://lore.kernel.org/r/20200805142136.0331f7ea@canb.auug.org.au
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
> Signed-off-by: Muchun Song <songmuchun@...edance.com>

Looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thank you!

> ---
>  kernel/kprobes.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 503add629599..d36e2b017588 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1114,9 +1114,20 @@ static int disarm_kprobe_ftrace(struct kprobe *p)
>  		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
>  }
>  #else	/* !CONFIG_KPROBES_ON_FTRACE */
> -#define prepare_kprobe(p)	arch_prepare_kprobe(p)
> -#define arm_kprobe_ftrace(p)	(-ENODEV)
> -#define disarm_kprobe_ftrace(p)	(-ENODEV)
> +static inline int prepare_kprobe(struct kprobe *p)
> +{
> +	return arch_prepare_kprobe(p);
> +}
> +
> +static inline int arm_kprobe_ftrace(struct kprobe *p)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int disarm_kprobe_ftrace(struct kprobe *p)
> +{
> +	return -ENODEV;
> +}
>  #endif
>  
>  /* Arm a kprobe with text_mutex */
> -- 
> 2.11.0
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>