Re: [PATCH v4 1/4] perf config: Introduce perf_config_set class

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Mar 29, 2016 at 09:43:13AM +0900, Taeung Song escreveu:
> This infrastructure code was designed for
> upcoming features of perf-config.
> 
> That collect config key-value pairs from user and
> system config files (i.e. user wide ~/.perfconfig
> and system wide $(sysconfdir)/perfconfig)
> to manage perf's configs.
> 
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
> ---
>  tools/perf/util/config.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/config.h |  26 +++++++
>  2 files changed, 197 insertions(+)
>  create mode 100644 tools/perf/util/config.h
> 
> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
> index 4e72763..2dbf47c 100644
> --- a/tools/perf/util/config.c
> +++ b/tools/perf/util/config.c
> @@ -13,6 +13,7 @@
>  #include <subcmd/exec-cmd.h>
>  #include "util/hist.h"  /* perf_hist_config */
>  #include "util/llvm-utils.h"   /* perf_llvm_config */
> +#include "config.h"
>  
>  #define MAXNAME (256)
>  
> @@ -506,6 +507,176 @@ out:
>  	return ret;
>  }
>  
> +static struct perf_config_section *find_section(struct list_head *sections,
> +						const char *section_name)
> +{
> +	struct perf_config_section *section;
> +
> +	list_for_each_entry(section, sections, list)
> +		if (!strcmp(section->name, section_name))
> +			return section;
> +
> +	return NULL;
> +}
> +
> +static struct perf_config_item *find_config_item(const char *name,
> +						 struct perf_config_section *section)
> +{
> +	struct perf_config_item *config_item;
> +
> +	list_for_each_entry(config_item, &section->config_items, list)
> +		if (!strcmp(config_item->name, name))
> +			return config_item;
> +
> +	return NULL;
> +}
> +
> +static void find_config(struct list_head *sections,
> +			struct perf_config_section **section,
> +			struct perf_config_item **config_item,
> +			const char *section_name, const char *name)
> +{
> +	*section = find_section(sections, section_name);
> +
> +	if (*section != NULL)
> +		*config_item = find_config_item(name, *section);
> +	else
> +		*config_item = NULL;

> +}
> +
> +static struct perf_config_section *add_section(struct list_head *sections,
> +					       const char *section_name)
> +{
> +	struct perf_config_section *section = zalloc(sizeof(*section));
> +
> +	if (!section)
> +		return NULL;
> +
> +	INIT_LIST_HEAD(&section->config_items);
> +	section->name = strdup(section_name);
> +	if (!section->name) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		free(section);
> +		return NULL;
> +	}
> +
> +	list_add_tail(&section->list, sections);
> +	return section;
> +}
> +
> +static struct perf_config_item *add_config_item(struct perf_config_section *section,
> +						const char *name)
> +{
> +	struct perf_config_item *config_item = zalloc(sizeof(*config_item));
> +
> +	if (!config_item)
> +		return NULL;
> +
> +	config_item->name = strdup(name);
> +	if (!name) {

Huh? You're testing the wrong variable.

> +		pr_err("%s: strdup failed\n", __func__);
> +		goto out_err;
> +	}
> +
> +	list_add_tail(&config_item->list, &section->config_items);
> +	return config_item;
> +
> +out_err:
> +	free(config_item);
> +	return NULL;
> +}
> +
> +static int set_value(struct perf_config_item *config_item, const char *value)
> +{
> +	char *val = strdup(value);
> +
> +	if (!val)
> +		return -1;
> +
> +	free(config_item->value);
> +	config_item->value = val;
> +	return 0;
> +}
> +
> +static int collect_config(const char *var, const char *value,
> +			  void *perf_config_set)
> +{
> +	int ret = -1;
> +	char *ptr, *key;
> +	char *section_name, *name;
> +	struct perf_config_section *section = NULL;
> +	struct perf_config_item *config_item = NULL;
> +	struct perf_config_set *perf_configs = perf_config_set;
> +	struct list_head *sections = &perf_configs->sections;
> +
> +	key = ptr = strdup(var);
> +	if (!key) {
> +		pr_err("%s: strdup failed\n", __func__);

pr_debug()

> +		return -1;
> +	}
> +
> +	section_name = strsep(&ptr, ".");
> +	name = ptr;
> +	if (name == NULL || value == NULL)
> +		goto out_free;
> +
> +	find_config(sections, &section, &config_item, section_name, name);

This idiom is confusing, why not ditch this 'find_config()' function and
do the searches here? I.e.:

	section = find_section(sections, section_name);
> +	if (!section) {
> +		section = add_section(sections, section_name);
> +		if (!section)
> +			goto out_free;
> +	}

 	config_item = find_config_item(name, section);
> +	if (!config_item) {
> +		config_item = add_config_item(section, name);
> +		if (!config_item)
> +			goto out_free;
> +	}
> +
> +	ret = set_value(config_item, value);
> +	return ret;
> +
> +out_free:
> +	free(key);
> +	perf_config_set__delete(perf_configs);
> +	return -1;
> +}
> +
> +struct perf_config_set *perf_config_set__new(void)
> +{
> +	struct perf_config_set *perf_configs = zalloc(sizeof(*perf_configs));
> +
> +	if (!perf_configs)
> +		return NULL;
> +
> +	INIT_LIST_HEAD(&perf_configs->sections);
> +	perf_config(collect_config, perf_configs);
> +
> +	return perf_configs;
> +}

Usually for these short functions we could do it more compactly as:

struct perf_config_set *perf_config_set__new(void)
{
	struct perf_config_set *perf_configs = zalloc(sizeof(*perf_configs));

	if (perf_configs) {
		INIT_LIST_HEAD(&perf_configs->sections);
		perf_config(collect_config, perf_configs);
	}

	return perf_configs;
}

But I'm not dwelling on this...

> +void perf_config_set__delete(struct perf_config_set *perf_configs)
> +{
> +	struct perf_config_section *section, *section_tmp;
> +	struct perf_config_item *config_item, *item_tmp;
> +
> +	list_for_each_entry_safe(section, section_tmp,
> +				 &perf_configs->sections, list) {
> +		list_for_each_entry_safe(config_item, item_tmp,
> +					 &section->config_items, list) {
> +			list_del(&config_item->list);
> +			free(config_item->name);
> +			free(config_item->value);
> +			free(config_item);
> +		}
> +		list_del(&section->list);
> +		free(section->name);
> +		free(section);
> +	}
> +
> +	free(perf_configs);
> +}

What is the problem with having perf_config_item__delete() and
perf_config_section__delete() and then have it like below, also please
rename those foo->list to foo->node.

void perf_config_item__delete(struct perf_config_item *item)
{
	zfree(&item->name);
	zfree(&item->value);
	free(item);
}

void perf_config_section__purge(struct perf_config_section *section)
{
	struct perf_config_item *item, *tmp;

	list_for_each_entry_safe(item, tmp, &section->items, node) {
		list_del_init(&item->node);
		perf_config_item__delete(item);
	}
}

void perf_config_section__delete(struct perf_config_section *section)
{
	perf_config_section__purge(section);
	zfree(&section->name);
	free(section);
}

void perf_config_set__purge(struct perf_config_set *set)
{
	struct perf_config_section *section, *tmp;

	list_for_each_entry_safe(section, tmp, &set->sections, node) {
		list_del_init(&section->node);
		perf_config_section__delete(section);
	}
}

void perf_config_set__delete(struct perf_config_set *set)
{
	perf_config_set__purge(set);
	free(set);
}

Using zfree() and list_del_init to NULL or poison the freed pointers
helps with debugging, please use them.

> +
>  /*
>   * Call this to report error for your variable that should not
>   * get a boolean value (i.e. "[my] var" means "true").
> diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
> new file mode 100644
> index 0000000..e270e51
> --- /dev/null
> +++ b/tools/perf/util/config.h
> @@ -0,0 +1,26 @@
> +#ifndef __PERF_CONFIG_H
> +#define __PERF_CONFIG_H
> +
> +#include <stdbool.h>
> +#include <linux/list.h>
> +
> +struct perf_config_item {
> +	char *name;
> +	char *value;
> +	struct list_head list;

s/list/node/g

> +};
> +
> +struct perf_config_section {
> +	char *name;
> +	struct list_head config_items;

s/config_items/items/g

> +	struct list_head list;

s/list/node/g
> +};
> +
> +struct perf_config_set {
> +	struct list_head sections;

See? Here you did it right, no point in having it as "config_sections"

> +};
> +
> +struct perf_config_set *perf_config_set__new(void);
> +void perf_config_set__delete(struct perf_config_set *perf_configs);

   void perf_config_set__delete(struct perf_config_set *set);

> +
> +#endif /* __PERF_CONFIG_H */
> -- 
> 2.5.0