linux-kernel - Re: [PATCH 3/8] signal: make may_ptrace

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Message-ID: <20180528141219.GZ30522@ZenIV.linux.org.uk>
Date:   Mon, 28 May 2018 15:12:19 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Christian Brauner <christian@...uner.io>
Cc:     linux-kernel@...r.kernel.org, ebiederm@...ssion.com,
        gregkh@...uxfoundation.org, mingo@...nel.org,
        james.morris@...rosoft.com, keescook@...omium.org,
        peterz@...radead.org, sds@...ho.nsa.gov, akpm@...ux-foundation.org,
        oleg@...hat.com
Subject: Re: [PATCH 3/8] signal: make may_ptrace_stop() return bool

On Mon, May 28, 2018 at 03:49:11PM +0200, Christian Brauner wrote:
> may_ptrace_stop() already behaves like a boolean function. Let's actually
> declare it as such too.
> 
> Signed-off-by: Christian Brauner <christian@...uner.io>
> ---
>  kernel/signal.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 81be01d193f4..6c2e7b45cba1 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1889,10 +1889,10 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
>  	spin_unlock_irqrestore(&sighand->siglock, flags);
>  }
>  
> -static inline int may_ptrace_stop(void)
> +static inline bool may_ptrace_stop(void)
>  {
>  	if (!likely(current->ptrace))
> -		return 0;
> +		return false;
>  	/*
>  	 * Are we in the middle of do_coredump?
>  	 * If so and our tracer is also part of the coredump stopping
> @@ -1908,9 +1908,9 @@ static inline int may_ptrace_stop(void)
>  	 */
>  	if (unlikely(current->mm->core_state) &&
>  	    unlikely(current->mm == current->parent->mm))
> -		return 0;
> +		return false;
>  
> -	return 1;
> +	return true;

	return !current->mm->core_state || current->mm != current->parent->mm;

or, if it gives any measurably better code generation,

	return likely(!current->mm->core_state ||
			current->mm != current->parent->mm);