linux-kernel - Re: [PATCH] printf: fix Woverride-init warning for EDEADLK errno

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Date:   Tue, 27 Oct 2020 08:25:43 +0100
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Arnd Bergmann <arnd@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Petr Mladek <pmladek@...e.com>,
        Uwe Kleine-König <uwe@...ine-koenig.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printf: fix Woverride-init warning for EDEADLK errno

On 27/10/2020 08.23, Rasmus Villemoes wrote:

> How about we do this instead?
> 
> From: Rasmus Villemoes <linux@...musvillemoes.dk>

Missed:

Subject: lib/errname.o: disable -Woverride-init

> 
> The table of errno value->name contains a few duplicate entries since
> e.g. EDEADLK == EDEADLOCK on most architectures. For the known cases,
> the most used symbolic constant is listed last so that takes
> precedence - the idea being that if someone sees "can't do that:
> -EDEADLK" in dmesg, grepping for EDEADLK is more likely to find the
> place where that error was generated (grepping for "can't do that"
> will find the printk() that emitted it, but the source would often be
> a few calls down).
> 
> However, that means one gets
> 
>   warning: initialized field overwritten [-Woverride-init]
> 
> when building with W=1. As the use of multiple initializers for the
> same entry here is quite deliberate, explicitly disable that warning
> for errname.o.
> 
> Reported-by: Arnd Bergmann <arnd@...nel.org>
> Fixes: 57f5677e535b ("printf: add support for printing symbolic error
> names")
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
> ---
>  lib/Makefile | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/Makefile b/lib/Makefile
> index ce45af50983a2a5e3582..a98119519e100103818d 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -224,6 +224,7 @@ obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
> 
>  obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o
>  obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
> +CFLAGS_errname.o += $(call cc-disable-warning, override-init)
> 
>  obj-$(CONFIG_NLATTR) += nlattr.o
> 


-- 
Rasmus Villemoes
Software Developer
Prevas A/S
Hedeager 3
DK-8200 Aarhus N
+45 51210274
rasmus.villemoes@...vas.dk
www.prevas.dk