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

From: Arnaldo Carvalho de Melo
Date: Thu Mar 31 2016 - 13:33:20 EST

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In reply to: Taeung Song: "Re: [PATCH v4 1/4] perf config: Introduce perf_config_set class"
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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@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
> ---
> 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

Next message: Dmitry Torokhov: "Re: [PATCH v2] gpio / ACPI: ignore GpioInt() GPIOs when requesting GPIO_OUT_*"
Previous message: Srinivas Kandagatla: "[PATCH v2 0/3] ahci: add ports-implemented dt bindings."
In reply to: Taeung Song: "Re: [PATCH v4 1/4] perf config: Introduce perf_config_set class"
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