linux-kernel - Re: [PATCH] [v2] printf: fix errname.c list

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Date:   Mon, 17 May 2021 09:26:13 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Uwe Kleine-König <uwe@...ine-koenig.org>,
        Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] printf: fix errname.c list

On Fri, May 14, 2021 at 11:34:50PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> On most architectures, gcc -Wextra warns about the list of error
> numbers containing both EDEADLK and EDEADLOCK:
> 
> lib/errname.c:15:67: warning: initialized field overwritten [-Woverride-init]
>    15 | #define E(err) [err + BUILD_BUG_ON_ZERO(err <= 0 || err > 300)] = "-" #err
>       |                                                                   ^~~
> lib/errname.c:172:2: note: in expansion of macro 'E'
>   172 |  E(EDEADLK), /* EDEADLOCK */
>       |  ^
> 
> On parisc, a similar error happens with -ECANCELLED, which is an
> alias for ECANCELED.
> 
> Make the EDEADLK printing conditional on the number being distinct
> from EDEADLOCK, and remove the -ECANCELLED bit completely as it
> can never be hit.
> 
> To ensure these are correct, add static_assert lines that verify
> all the remaining aliases are in fact identical to the canonical
> name.

Looks good to me, thanks for fixing this.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Fixes: 57f5677e535b ("printf: add support for printing symbolic error names")
> Cc: Petr Mladek <pmladek@...e.com>
> Suggested-by: Rasmus Villemoes <linux@...musvillemoes.dk>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  lib/errname.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/errname.c b/lib/errname.c
> index 05cbf731545f..6c5c0aa4de75 100644
> --- a/lib/errname.c
> +++ b/lib/errname.c
> @@ -21,6 +21,7 @@ static const char *names_0[] = {
>  	E(EADDRNOTAVAIL),
>  	E(EADV),
>  	E(EAFNOSUPPORT),
> +	E(EAGAIN), /* EWOULDBLOCK */
>  	E(EALREADY),
>  	E(EBADE),
>  	E(EBADF),
> @@ -38,8 +39,12 @@ static const char *names_0[] = {
>  	E(ECHRNG),
>  	E(ECOMM),
>  	E(ECONNABORTED),
> +	E(ECONNREFUSED), /* EREFUSED */
>  	E(ECONNRESET),
> +	E(EDEADLK), /* EDEADLOCK */
> +#if EDEADLK != EDEADLOCK /* mips, sparc, powerpc */
>  	E(EDEADLOCK),
> +#endif
>  	E(EDESTADDRREQ),
>  	E(EDOM),
>  	E(EDOTDOT),
> @@ -166,14 +171,17 @@ static const char *names_0[] = {
>  	E(EUSERS),
>  	E(EXDEV),
>  	E(EXFULL),
> -
> -	E(ECANCELED), /* ECANCELLED */
> -	E(EAGAIN), /* EWOULDBLOCK */
> -	E(ECONNREFUSED), /* EREFUSED */
> -	E(EDEADLK), /* EDEADLOCK */
>  };
>  #undef E
>  
> +#ifdef EREFUSED /* parisc */
> +static_assert(EREFUSED == ECONNREFUSED);
> +#endif
> +#ifdef ECANCELLED /* parisc */
> +static_assert(ECANCELLED == ECANCELED);
> +#endif
> +static_assert(EAGAIN == EWOULDBLOCK); /* everywhere */
> +
>  #define E(err) [err - 512 + BUILD_BUG_ON_ZERO(err < 512 || err > 550)] = "-" #err
>  static const char *names_512[] = {
>  	E(ERESTARTSYS),
> -- 
> 2.29.2
> 

-- 
With Best Regards,
Andy Shevchenko