linux-kernel - Re: [PATCH] modpost: simplify modpost

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Message-ID: <20240812212256.GA3675407@thelio-3990X>
Date: Mon, 12 Aug 2024 14:22:56 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
	Nicolas Schier <nicolas@...sle.eu>
Subject: Re: [PATCH] modpost: simplify modpost_log()

Hi Masahiro,

On Mon, Aug 12, 2024 at 11:45:39PM +0900, Masahiro Yamada wrote:
> With commit cda5f94e88b4 ("modpost: avoid using the alias attribute"),
> only two log levels remain: LOG_WARN and LOG_ERROR. Simplify this by
> making it a boolean variable.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
> 
>  scripts/mod/modpost.c | 17 ++++++-----------
>  scripts/mod/modpost.h | 11 +++--------
>  2 files changed, 9 insertions(+), 19 deletions(-)
> 
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index d0f138803207..c896872862dc 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -67,20 +67,15 @@ static unsigned int nr_unresolved;
>  
>  #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
>  
> -void modpost_log(enum loglevel loglevel, const char *fmt, ...)
> +void modpost_log(bool is_error, const char *fmt, ...)
>  {
>  	va_list arglist;
>  
> -	switch (loglevel) {
> -	case LOG_WARN:
> -		fprintf(stderr, "WARNING: ");
> -		break;
> -	case LOG_ERROR:
> +	if (is_error) {
>  		fprintf(stderr, "ERROR: ");
>  		error_occurred = true;
> -		break;
> -	default: /* invalid loglevel, ignore */
> -		break;
> +	} else {
> +		fprintf(stderr, "WARNING: ");
>  	}
>  
>  	fprintf(stderr, "modpost: ");
> @@ -1692,7 +1687,7 @@ static void check_exports(struct module *mod)
>  		exp = find_symbol(s->name);
>  		if (!exp) {
>  			if (!s->weak && nr_unresolved++ < MAX_UNRESOLVED_REPORTS)
> -				modpost_log(warn_unresolved ? LOG_WARN : LOG_ERROR,
> +				modpost_log(warn_unresolved,

I think the logic is reversed here? If warn_unresolved was true before,
LOG_WARN would be used but I think warn_unresolved being true with this
change would trigger the behavior of LOG_ERROR. Should it be
'!warn_unresolved'?

>  					    "\"%s\" [%s.ko] undefined!\n",
>  					    s->name, mod->name);
>  			continue;
> @@ -1715,7 +1710,7 @@ static void check_exports(struct module *mod)
>  			basename = mod->name;
>  
>  		if (!contains_namespace(&mod->imported_namespaces, exp->namespace)) {
> -			modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
> +			modpost_log(allow_missing_ns_imports,

Same thing here?

Alternatively, I suppose the logic could be reversed in modpost_log()
and is_error could be turned into no_error or something?

>  				    "module %s uses symbol %s from namespace %s, but does not import it.\n",
>  				    basename, exp->name, exp->namespace);
>  			add_namespace(&mod->missing_namespaces, exp->namespace);
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index f756e6578b9e..6f418f0afd04 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -184,13 +184,8 @@ char *read_text_file(const char *filename);
>  char *get_line(char **stringp);
>  void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym);
>  
> -enum loglevel {
> -	LOG_WARN,
> -	LOG_ERROR,
> -};
> -
>  void __attribute__((format(printf, 2, 3)))
> -modpost_log(enum loglevel loglevel, const char *fmt, ...);
> +modpost_log(bool is_error, const char *fmt, ...);
>  
>  /*
>   * warn - show the given message, then let modpost continue running, still
> @@ -205,6 +200,6 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
>   * fatal - show the given message, and bail out immediately. This should be
>   *         used when there is no point to continue running modpost.
>   */
> -#define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
> -#define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
> +#define warn(fmt, args...)	modpost_log(false, fmt, ##args)
> +#define error(fmt, args...)	modpost_log(true, fmt, ##args)

I suppose the declaration of modpost_log() is close enough to see what
the true/false argument means but maybe something like

  modpost_log(/* is_error = */ false, ...)

could be nice? No strong opinion here though, feel free to just ignore
this whole comment entirely if you disagree!

>  #define fatal(fmt, args...)	do { error(fmt, ##args); exit(1); } while (1)
> -- 
> 2.43.0
>