Message-ID: <56FE4D0A.60200@gmail.com>
Date:	Fri, 1 Apr 2016 19:27:22 +0900
From:	Taeung Song <treeze.taeung@...il.com>
To:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:	Namhyung Kim <namhyung@...nel.org>, linux-kernel@...r.kernel.org,
	Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v4 1/4] perf config: Introduce perf_config_set class

Hi, Arnaldo

Thank you for your review.

On 04/01/2016 02:31 AM, Arnaldo Carvalho de Melo wrote:
> 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@...nel.org>
>> Cc: Jiri Olsa <jolsa@...nel.org>
>> Signed-off-by: Taeung Song <treeze.taeung@...il.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.
>

Sorry, my stupid mistake..

>> +		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()
>

I'll change pr_err to pr_debug.
But why do use pr_debug at only this part ?

>> +		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);

I got it.
I think it is needed to remove needless find_config() function as you said.

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

ok.

>> +	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...
>

I got it, too!

>> +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.
>

No problem!
OK, I'll rename it.

> 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.

ok.

>
>> +
>>   /*
>>    * 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"
>

I'll rename it to '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);
>

OK, I'll use 'set' variable name instead of perf_configs on this source 
file.

I'll resend this patch after modifying what you said. :-)

Thanks,
Taeung

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

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