linux-kernel - Re: [PATCH v2] apparmor: add braces around optional statement

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Message-ID: <20170620204953.GA25573@mail.hallyn.com>
Date:   Tue, 20 Jun 2017 15:49:53 -0500
From:   "Serge E. Hallyn" <serge@...lyn.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     John Johansen <john.johansen@...onical.com>,
        James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] apparmor: add braces around optional statement

Quoting Arnd Bergmann (arnd@...db.de):
> We get a warning when AA_BUG() compiles to an nothing:
> 
> security/apparmor/label.c: In function '__label_update':
> security/apparmor/label.c:2055:3: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
> 
> There are two things we can do about this:
> 
> - add the missing braces in the call site, which also
>   brings the code in line with the regular Linux coding style
> 
> - redefine the macro so it is not empty but instead uses
>   no_printk() in AA_BUG_FMT() to perform format checking.
> 
> Both seem like good ideas, so this does both at once.
> 
> Fixes: f1bd904175e8 ("apparmor: add the base fns() for domain labels")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Acked-by: Serge Hallyn <serge@...lyn.com>

> --
> v2: actually include the second part of the patch
> ---
>  security/apparmor/include/lib.h | 2 +-
>  security/apparmor/label.c       | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/security/apparmor/include/lib.h b/security/apparmor/include/lib.h
> index 436b3a722357..cbfb71c1ec88 100644
> --- a/security/apparmor/include/lib.h
> +++ b/security/apparmor/include/lib.h
> @@ -50,7 +50,7 @@
>  #define AA_BUG_FMT(X, fmt, args...)					\
>  	WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
>  #else
> -#define AA_BUG_FMT(X, fmt, args...)
> +#define AA_BUG_FMT(X, fmt, args...) no_printk("%s" fmt, __func__, ##args)
>  #endif
>  
>  #define AA_ERROR(fmt, args...)						\
> diff --git a/security/apparmor/label.c b/security/apparmor/label.c
> index e052eaba1cf6..f8e08d94a8a6 100644
> --- a/security/apparmor/label.c
> +++ b/security/apparmor/label.c
> @@ -2051,8 +2051,9 @@ static struct aa_label *__label_update(struct aa_label *label)
>  			write_lock_irqsave(&ls->lock, flags);
>  			goto remove;
>  		}
> -	} else
> +	} else {
>  		AA_BUG(labels_ns(label) != labels_ns(new));
> +	}
>  
>  	tmp = __label_insert(labels_set(label), new, true);
>  remove:
> -- 
> 2.9.0