linux-kernel - Re: [PATCH v7 3/7] perf config: Add global variable 'config

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Date:	Tue, 7 Jun 2016 11:05:09 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Taeung Song <treeze.taeung@...il.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH v7 3/7] perf config: Add global variable 'config_set'

Em Tue, Jun 07, 2016 at 06:26:13PM +0900, Taeung Song escreveu:
> The config set is prepared by collecting
> all configs from config files (i.e. user config
> ~/.perfconfig and system config $(sysconfdir)/perfconfig)
> so the config set contains all config key-value pairs.
> 
> We need to use it as global variable to share it.

We should generally avoid global variables, and in this case, from
looking just at this patch, I'm not convinced we need to introduce more
global variables, isn't this object instantiated and deleted at the
cmd_config() function? So, can't we just pass it to any function needing
to access it?

I applied the first two patches.

- Arnaldo

> And in near future, the variable will be handled in perf_config()
> and other functions at util/config.c
> 
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
> ---
>  tools/perf/builtin-config.c | 9 ++++-----
>  tools/perf/util/config.c    | 1 +
>  tools/perf/util/config.h    | 2 ++
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
> index fe1b77f..b3bc01a 100644
> --- a/tools/perf/builtin-config.c
> +++ b/tools/perf/builtin-config.c
> @@ -62,7 +62,6 @@ static int show_config(struct perf_config_set *set)
>  int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>  {
>  	int ret = 0;
> -	struct perf_config_set *set;
>  	char *user_config = mkpath("%s/.perfconfig", getenv("HOME"));
>  
>  	argc = parse_options(argc, argv, config_options, config_usage,
> @@ -80,8 +79,8 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>  	else if (use_user_config)
>  		config_exclusive_filename = user_config;
>  
> -	set = perf_config_set__new();
> -	if (!set) {
> +	config_set = perf_config_set__new();
> +	if (!config_set) {
>  		ret = -1;
>  		goto out_err;
>  	}
> @@ -92,7 +91,7 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>  			pr_err("Error: takes no arguments\n");
>  			parse_options_usage(config_usage, config_options, "l", 1);
>  		} else {
> -			ret = show_config(set);
> +			ret = show_config(config_set);
>  			if (ret < 0) {
>  				const char * config_filename = config_exclusive_filename;
>  				if (!config_exclusive_filename)
> @@ -106,7 +105,7 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>  		usage_with_options(config_usage, config_options);
>  	}
>  
> -	perf_config_set__delete(set);
> +	perf_config_set__delete(config_set);
>  out_err:
>  	return ret;
>  }
> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
> index 8749eca..02fc6d5 100644
> --- a/tools/perf/util/config.c
> +++ b/tools/perf/util/config.c
> @@ -28,6 +28,7 @@ static int config_linenr;
>  static int config_file_eof;
>  
>  const char *config_exclusive_filename;
> +struct perf_config_set *config_set;
>  
>  static int get_next_char(void)
>  {
> diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
> index 22ec626..ea157a4 100644
> --- a/tools/perf/util/config.h
> +++ b/tools/perf/util/config.h
> @@ -20,6 +20,8 @@ struct perf_config_set {
>  	struct list_head sections;
>  };
>  
> +extern struct perf_config_set *config_set;
> +
>  struct perf_config_set *perf_config_set__new(void);
>  void perf_config_set__delete(struct perf_config_set *set);
>  
> -- 
> 2.5.0