Date:	Mon, 27 Jul 2015 17:38:39 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Taeung Song <treeze.taeung@...il.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org, jolsa@...hat.com,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v4 3/5] perf config: Add functions which can get or set
 perf config variables

On Mon, Jul 27, 2015 at 12:58:29AM +0900, Taeung Song wrote:
> This patch consists of functions
> which can get, set specific config variables.

I think you'd be better splitting this patch into pieces.  I'd like to
do it with 3 patches - one for adding default config set (possibly
squash/reorder --list-all patch too), next is for adding 'get'
functionality, and finally adding 'set' feature.  It'll make the
reviewer's life little easier. :)

Nitpicks below...


> For the syntax examples,
> 
>    perf config [options] [section.name[=value] ...]
> 
>    display key-value pairs of specific config variables
>    # perf config report.queue-size report.children
> 
>    set specific config variables
>    # perf config report.queue-size=100M report.children=true
> 
> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
> ---


[SNIP]
> +	{
> +		.section_name = KMEM,
> +		.name = "default",
> +		.value = "page",

s/page/slab/


> +		.type = NULL,
> +	},
> +	{
> +		.section_name = NULL,
> +		.name = NULL,
> +		.value = NULL,
> +		.type = NULL,
> +	},
> +};
> +

[SNIP]
> +static int add_element(struct list_head *head,
> +			      const char *name, const char *value)
> +{
> +	struct config_element *element_node;
> +
> +	element_node = zalloc(sizeof(*element_node));

Need to check return value here.


> +	element_node->name = strdup(name);
> +	if (!element_node->name) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		goto out_free;
> +	}
> +	if (value)
> +		element_node->value = (char *)value;
> +	else
> +		element_node->value = NULL;
> +
> +	list_add_tail(&element_node->list, head);
> +	return 0;
> +
> +out_free:
> +	free(element_node);
> +	return -1;
> +}
> +
>  static int show_config(const char *key, const char *value,
>  		       void *cb __maybe_unused)
>  {
> @@ -45,10 +392,203 @@ static int show_config(const char *key, const char *value,
>  	return 0;
>  }
>  
> +static void find_config(struct config_section **section_node,
> +			struct config_element **element_node,
> +			const char *section_name, const char *name)
> +{
> +	*section_node = find_section(section_name);
> +
> +	if (*section_node != NULL)
> +		*element_node = find_element(name, *section_node);
> +	else
> +		*element_node = NULL;
> +}
> +
> +static int show_spec_config(const char *section_name, const char *name,
> +			    char *value __maybe_unused)
> +{
> +	int i;
> +	struct config_section *section_node = NULL;
> +	struct config_element *element_node = NULL;
> +	char key[BUFSIZ];
> +
> +	find_config(&section_node, &element_node, section_name, name);
> +
> +	if (section_node && element_node) {
> +		scnprintf(key, sizeof(key), "%s.%s",
> +			  section_node->name, element_node->name);
> +		return show_config(key, element_node->value, NULL);
> +	}
> +
> +	for (i = 0; default_configsets[i].section_name != NULL; i++) {

I'd do this with a local variable:

		struct default_configset *config = &default_configsets[i];


> +		if (!strcmp(default_configsets[i].section_name, section_name)
> +		    && !strcmp(default_configsets[i].name, name)) {

Please put the '&&' operator in the above line.


> +			printf("%s.%s=%s (default)\n", default_configsets[i].section_name,
> +			       default_configsets[i].name, default_configsets[i].value);
> +			return 0;
> +		}
> +	}
> +
> +	pr_err("Error: Failed to find the variable.\n");
> +
> +	return 0;
> +}
> +
> +static char *normalize_value(const char *section_name, const char *name, const char *value)
> +{
> +	int i;
> +	char key[BUFSIZ];
> +	char *normalized;
> +
> +	scnprintf(key, sizeof(key), "%s.%s", section_name, name);
> +	for (i = 0; default_configsets[i].section_name != NULL; i++) {

Ditto for default_configsets[i].


> +		if (!strcmp(default_configsets[i].section_name, section_name)
> +		    && !strcmp(default_configsets[i].name, name)) {
> +			normalized = zalloc(BUFSIZ);

Instead of always allocating BUFSIZ memory, please use asprintf().


> +			if (!default_configsets[i].type)
> +				scnprintf(normalized, BUFSIZ, "%s", value);
> +			else if (!strcmp(default_configsets[i].type, TYPE_BOOL))
> +				scnprintf(normalized, BUFSIZ, "%s",
> +					  perf_config_bool(key, value) ? "true" : "false");
> +			else if (!strcmp(default_configsets[i].type, TYPE_ON_OFF))
> +				scnprintf(normalized, BUFSIZ, "%s",
> +					  perf_config_bool(key, value) ? "on" : "off");
> +			else if (!strcmp(default_configsets[i].type, TYPE_INT))
> +				scnprintf(normalized, BUFSIZ, "%d",
> +					  perf_config_int(key, value));
> +			else if (!strcmp(default_configsets[i].type, TYPE_LONG))
> +				scnprintf(normalized, BUFSIZ, "%"PRId64,
> +					  perf_config_u64(key, value));
> +			else if (!strcmp(default_configsets[i].type, TYPE_DIRNAME))
> +				scnprintf(normalized, BUFSIZ, "%s",
> +					  perf_config_dirname(key, value));
> +			return normalized;
> +		}
> +	}
> +
> +	normalized = strdup(value);
> +	if (!normalized) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		return NULL;
> +	}
> +
> +	return normalized;
> +}
> +
> +static int set_config(const char *section_name, const char *name, char *value)
> +{
> +	struct config_section *section_node = NULL;
> +	struct config_element *element_node = NULL;
> +
> +	find_config(&section_node, &element_node, section_name, name);
> +	if (value != NULL) {
> +		value = normalize_value(section_name, name, value);
> +
> +		/* if there isn't existent section, add a new section */
> +		if (!section_node) {
> +			section_node = init_section(section_name);
> +			if (!section_node)
> +				return -1;
> +			list_add_tail(&section_node->list, &sections);
> +		}
> +		/* if nothing to replace, add a new element which contains key-value pair. */
> +		if (!element_node) {
> +			add_element(&section_node->element_head, name, value);
> +		} else {
> +			if (!element_node->value)
> +				free(element_node->value);

I guess you wanted to check NULL pointer before freeing the old value.
It's inverted, but anyway you can skip the check since free() already
ignored NULL pointers.


> +			element_node->value = value;
> +		}
> +	}
> +
> +	if (access(config_file_name, W_OK) == -1) {
> +		pr_err("Error: %s: Can't write to this file or no such file\n",
> +		       config_file_name);

Not sure we need to error out in the 'no such file' case.  Maybe it's
ok to create a new file..


> +		return -1;
> +	}
> +
> +	return perf_configset_write_in_full(config_file_name);
> +}
> +
> +static int collect_current_config(const char *var, const char *value,
> +			  void *cb __maybe_unused)
> +{
> +	struct config_section *section_node;
> +	char *key = strdup(var);

Who does free the key?


> +	char *section_name, *name;
> +
> +	if (!key) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		return -1;
> +	}
> +
> +	section_name = strsep(&key, ".");
> +	name = strsep(&key, ".");
> +	if (name == NULL)
> +		return -1;
> +
> +	section_node = find_section(section_name);
> +	if (!section_node) {
> +		section_node = init_section(section_name);
> +		if (!section_node)
> +			return -1;
> +		list_add_tail(&section_node->list, &sections);
> +	}
> +
> +	return add_element(&section_node->element_head, name,
> +			   normalize_value(section_name, name, value));
> +}
> +
> +static int perf_configset_with_option(configset_fn_t fn, const char *var, char *value)
> +{
> +	char *section_name;
> +	char *name;
> +	const char *last_dot;
> +	char *key = strdup(var);

Ditto.

Thanks,
Namhyung


> +
> +	if (!key) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		return -1;
> +	}
> +	last_dot = strchr(key, '.');
> +	/*
> +	 * Since "key" actually contains the section name and the real
> +	 * key name separated by a dot, we have to know where the dot is.
> +	 */
> +	if (last_dot == NULL || last_dot == key) {
> +		pr_err("The config variable does not contain a section: %s\n", key);
> +		return -1;
> +	}
> +	if (!last_dot[1]) {
> +		pr_err("The config varible does not contain variable name: %s\n", key);
> +		return -1;
> +	}
> +
> +	section_name = strsep(&key, ".");
> +	name = strsep(&key, ".");
> +
> +	if (!value) {
> +		/* do nothing */
> +	} else if (!strcmp(value, "=")) {
> +		pr_err("The config variable does not contain a value: %s.%s\n",
> +		       section_name, name);
> +		return -1;
> +	} else {
> +		value++;
> +		name = strsep(&name, "=");
> +	}
> +
> +	return fn(section_name, name, value);
> +
> +	pr_err("invalid key: %s\n", var);
> +	return -1;
> +}
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