linux-kernel - Re: [PATCH 2/8] signal: make kill_as_cred

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Date:   Mon, 28 May 2018 15:07:49 +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 2/8] signal: make kill_as_cred_perm() return bool

On Mon, May 28, 2018 at 03:49:10PM +0200, Christian Brauner wrote:
> kill_as_cred_perm() 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 | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/signal.c b/kernel/signal.c
> index c756008d589e..81be01d193f4 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1349,14 +1349,15 @@ static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
>  	return error;
>  }
>  
> -static int kill_as_cred_perm(const struct cred *cred,
> +static bool kill_as_cred_perm(const struct cred *cred,
>  			     struct task_struct *target)
>  {
>  	const struct cred *pcred = __task_cred(target);
>  	if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
>  	    !uid_eq(cred->uid,  pcred->suid) && !uid_eq(cred->uid,  pcred->uid))
> -		return 0;
> -	return 1;
> +		return false;
> +
> +	return true;

Ugh...
	if (!foo && !bar && !baz && !quux)
		return false;
	return true;

is a bloody odd way to spell

	return foo || bar || baz || quux;