Commit 8a6d5fec authored by Matthew Wood's avatar Matthew Wood Committed by David S. Miller
Browse files

net: netconsole: add a userdata config_group member to netconsole_target 



Create configfs machinery for netconsole userdata appending, which depends
on CONFIG_NETCONSOLE_DYNAMIC (for configfs interface). Add a userdata
config_group to netconsole_target for managing userdata entries as a tree
under the netconsole configfs subsystem. Directory names created under the
userdata directory become userdatum keys; the userdatum value is the
content of the value file.

Include the minimum-viable-changes for userdata configfs config_group.
init_target_config_group() ties in the complete configfs machinery to
avoid unused func/variable errors during build. Initializing the
netconsole_target->group is moved to init_target_config_group, which
will also init and add the userdata config_group.

Each userdatum entry has a limit of 256 bytes (54 for
the key/directory, 200 for the value, and 2 for '=' and '\n'
characters), which is enforced by the configfs functions for updating
the userdata config_group.

When a new netconsole_target is created, initialize the userdata
config_group and add it as a default group for netconsole_target
config_group, allowing the userdata configfs sub-tree to be presented
in the netconsole configfs tree under the userdata directory.

Co-developed-by: default avatarBreno Leitao <leitao@debian.org>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Signed-off-by: default avatarMatthew Wood <thepacketgeek@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent aa7b608d

drivers/net/netconsole.c

+142 −5
Original line number Diff line number Diff line
@@ -43,6 +43,10 @@ MODULE_DESCRIPTION("Console driver for network interfaces"); 
MODULE_LICENSE("GPL");



#define MAX_PARAM_LENGTH	256

#define MAX_USERDATA_NAME_LENGTH	54

#define MAX_USERDATA_VALUE_LENGTH	200

#define MAX_USERDATA_ENTRY_LENGTH	256

#define MAX_USERDATA_ITEMS		16

#define MAX_PRINT_CHUNK		1000



static char config[MAX_PARAM_LENGTH];
@@ -80,6 +84,7 @@ static struct console netconsole_ext; 
 * struct netconsole_target - Represents a configured netconsole target.

 * @list:	Links this target into the target_list.

 * @group:	Links us into the configfs subsystem hierarchy.

 * @userdata_group:	Links to the userdata configfs hierarchy

 * @enabled:	On / off knob to enable / disable target.

 *		Visible from userspace (read-write).

 *		We maintain a strict 1:1 correspondence between this and
@@ -103,6 +108,7 @@ struct netconsole_target { 
	struct list_head	list;

#ifdef	CONFIG_NETCONSOLE_DYNAMIC

	struct config_group	group;

	struct config_group	userdata_group;

#endif

	bool			enabled;

	bool			extended;
@@ -215,6 +221,10 @@ static struct netconsole_target *alloc_and_init(void) 
 *				|	remote_ip

 *				|	local_mac

 *				|	remote_mac

 *				|	userdata/

 *				|		<key>/

 *				|			value

 *				|		...

 *				|

 *				<target>/...

 */
@@ -596,6 +606,123 @@ static ssize_t remote_mac_store(struct config_item *item, const char *buf, 
	return -EINVAL;

}



struct userdatum {

	struct config_item item;

	char value[MAX_USERDATA_VALUE_LENGTH];

};



static struct userdatum *to_userdatum(struct config_item *item)

{

	return container_of(item, struct userdatum, item);

}



struct userdata {

	struct config_group group;

};



static struct userdata *to_userdata(struct config_item *item)

{

	return container_of(to_config_group(item), struct userdata, group);

}



static struct netconsole_target *userdata_to_target(struct userdata *ud)

{

	struct config_group *netconsole_group;



	netconsole_group = to_config_group(ud->group.cg_item.ci_parent);

	return to_target(&netconsole_group->cg_item);

}



static ssize_t userdatum_value_show(struct config_item *item, char *buf)

{

	return sysfs_emit(buf, "%s\n", &(to_userdatum(item)->value[0]));

}



static ssize_t userdatum_value_store(struct config_item *item, const char *buf,

				     size_t count)

{

	struct userdatum *udm = to_userdatum(item);

	int ret;



	if (count > MAX_USERDATA_VALUE_LENGTH)

		return -EMSGSIZE;



	mutex_lock(&dynamic_netconsole_mutex);



	ret = strscpy(udm->value, buf, sizeof(udm->value));

	if (ret < 0)

		goto out_unlock;

	trim_newline(udm->value, sizeof(udm->value));



	mutex_unlock(&dynamic_netconsole_mutex);

	return count;

out_unlock:

	mutex_unlock(&dynamic_netconsole_mutex);

	return ret;

}



CONFIGFS_ATTR(userdatum_, value);



static struct configfs_attribute *userdatum_attrs[] = {

	&userdatum_attr_value,

	NULL,

};



static void userdatum_release(struct config_item *item)

{

	kfree(to_userdatum(item));

}



static struct configfs_item_operations userdatum_ops = {

	.release = userdatum_release,

};



static const struct config_item_type userdatum_type = {

	.ct_item_ops	= &userdatum_ops,

	.ct_attrs	= userdatum_attrs,

	.ct_owner	= THIS_MODULE,

};



static struct config_item *userdatum_make_item(struct config_group *group,

					       const char *name)

{

	struct netconsole_target *nt;

	struct userdatum *udm;

	struct userdata *ud;

	size_t child_count;



	if (strlen(name) > MAX_USERDATA_NAME_LENGTH)

		return ERR_PTR(-ENAMETOOLONG);



	ud = to_userdata(&group->cg_item);

	nt = userdata_to_target(ud);

	child_count = list_count_nodes(&nt->userdata_group.cg_children);

	if (child_count >= MAX_USERDATA_ITEMS)

		return ERR_PTR(-ENOSPC);



	udm = kzalloc(sizeof(*udm), GFP_KERNEL);

	if (!udm)

		return ERR_PTR(-ENOMEM);



	config_item_init_type_name(&udm->item, name, &userdatum_type);

	return &udm->item;

}



static struct configfs_attribute *userdata_attrs[] = {

	NULL,

};



static struct configfs_group_operations userdata_ops = {

	.make_item		= userdatum_make_item,

};



static struct config_item_type userdata_type = {

	.ct_item_ops	= &userdatum_ops,

	.ct_group_ops	= &userdata_ops,

	.ct_attrs	= userdata_attrs,

	.ct_owner	= THIS_MODULE,

};



CONFIGFS_ATTR(, enabled);

CONFIGFS_ATTR(, extended);

CONFIGFS_ATTR(, dev_name);
@@ -640,6 +767,15 @@ static const struct config_item_type netconsole_target_type = { 
	.ct_owner		= THIS_MODULE,

};



static void init_target_config_group(struct netconsole_target *nt,

				     const char *name)

{

	config_group_init_type_name(&nt->group, name, &netconsole_target_type);

	config_group_init_type_name(&nt->userdata_group, "userdata",

				    &userdata_type);

	configfs_add_default_group(&nt->userdata_group, &nt->group);

}



static struct netconsole_target *find_cmdline_target(const char *name)

{

	struct netconsole_target *nt, *ret = NULL;
@@ -674,16 +810,18 @@ static struct config_group *make_netconsole_target(struct config_group *group, 
	if (!strncmp(name, NETCONSOLE_PARAM_TARGET_PREFIX,

		     strlen(NETCONSOLE_PARAM_TARGET_PREFIX))) {

		nt = find_cmdline_target(name);

		if (nt)

		if (nt) {

			init_target_config_group(nt, name);

			return &nt->group;

		}

	}



	nt = alloc_and_init();

	if (!nt)

		return ERR_PTR(-ENOMEM);



	/* Initialize the config_item member */

	config_group_init_type_name(&nt->group, name, &netconsole_target_type);

	/* Initialize the config_group member */

	init_target_config_group(nt, name);



	/* Adding, but it is disabled */

	spin_lock_irqsave(&target_list_lock, flags);
@@ -740,8 +878,7 @@ static void populate_configfs_item(struct netconsole_target *nt, 


	snprintf(target_name, sizeof(target_name), "%s%d",

		 NETCONSOLE_PARAM_TARGET_PREFIX, cmdline_count);

	config_group_init_type_name(&nt->group, target_name,

				    &netconsole_target_type);

	init_target_config_group(nt, target_name);

}



#endif	/* CONFIG_NETCONSOLE_DYNAMIC */