Commit 364f6783 authored by Breno Leitao's avatar Breno Leitao Committed by David S. Miller
Browse files

netconsole: Introduce configfs helpers for sysdata features 



This patch introduces a bitfield to store sysdata features in the
netconsole_target struct. It also adds configfs helpers to enable
or disable the CPU_NR feature, which populates the CPU number in
sysdata.

The patch provides the necessary infrastructure to set or unset the
CPU_NR feature, but does not modify the message itself.

Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 563fe939

drivers/net/netconsole.c

+81 −0
Original line number Diff line number Diff line
@@ -97,6 +97,15 @@ struct netconsole_target_stats { 
	struct u64_stats_sync syncp;

};



/* Features enabled in sysdata. Contrary to userdata, this data is populated by

 * the kernel. The fields are designed as bitwise flags, allowing multiple

 * features to be set in sysdata_fields.

 */

enum sysdata_feature {

	/* Populate the CPU that sends the message */

	CPU_NR = BIT(0),

};



/**

 * struct netconsole_target - Represents a configured netconsole target.

 * @list:	Links this target into the target_list.
@@ -104,6 +113,7 @@ struct netconsole_target_stats { 
 * @userdata_group:	Links to the userdata configfs hierarchy

 * @extradata_complete:	Cached, formatted string of append

 * @userdata_length:	String length of usedata in extradata_complete.

 * @sysdata_fields:	Sysdata features enabled.

 * @stats:	Packet send stats for the target. Used for debugging.

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

 *		Visible from userspace (read-write).
@@ -132,6 +142,8 @@ struct netconsole_target { 
	struct config_group	userdata_group;

	char extradata_complete[MAX_EXTRADATA_ENTRY_LEN * MAX_EXTRADATA_ITEMS];

	size_t			userdata_length;

	/* bit-wise with sysdata_feature bits */

	u32			sysdata_fields;

#endif

	struct netconsole_target_stats stats;

	bool			enabled;
@@ -399,6 +411,19 @@ static ssize_t transmit_errors_show(struct config_item *item, char *buf) 
	return sysfs_emit(buf, "%llu\n", xmit_drop_count + enomem_count);

}



/* configfs helper to display if cpu_nr sysdata feature is enabled */

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

{

	struct netconsole_target *nt = to_target(item->ci_parent);

	bool cpu_nr_enabled;



	mutex_lock(&dynamic_netconsole_mutex);

	cpu_nr_enabled = !!(nt->sysdata_fields & CPU_NR);

	mutex_unlock(&dynamic_netconsole_mutex);



	return sysfs_emit(buf, "%d\n", cpu_nr_enabled);

}



/*

 * This one is special -- targets created through the configfs interface

 * are not enabled (and the corresponding netpoll activated) by default.
@@ -793,7 +818,62 @@ static ssize_t userdatum_value_store(struct config_item *item, const char *buf, 
	return ret;

}



/* disable_sysdata_feature - Disable sysdata feature and clean sysdata

 * @nt: target that is disabling the feature

 * @feature: feature being disabled

 */

static void disable_sysdata_feature(struct netconsole_target *nt,

				    enum sysdata_feature feature)

{

	nt->sysdata_fields &= ~feature;

	nt->extradata_complete[nt->userdata_length] = 0;

}



/* configfs helper to sysdata cpu_nr feature */

static ssize_t sysdata_cpu_nr_enabled_store(struct config_item *item,

					    const char *buf, size_t count)

{

	struct netconsole_target *nt = to_target(item->ci_parent);

	bool cpu_nr_enabled, curr;

	ssize_t ret;



	ret = kstrtobool(buf, &cpu_nr_enabled);

	if (ret)

		return ret;



	mutex_lock(&dynamic_netconsole_mutex);

	curr = nt->sysdata_fields & CPU_NR;

	if (cpu_nr_enabled == curr)

		/* no change requested */

		goto unlock_ok;



	if (cpu_nr_enabled &&

	    count_extradata_entries(nt) >= MAX_EXTRADATA_ITEMS) {

		/* user wants the new feature, but there is no space in the

		 * buffer.

		 */

		ret = -ENOSPC;

		goto unlock;

	}



	if (cpu_nr_enabled)

		nt->sysdata_fields |= CPU_NR;

	else

		/* This is special because extradata_complete might have

		 * remaining data from previous sysdata, and it needs to be

		 * cleaned.

		 */

		disable_sysdata_feature(nt, CPU_NR);



unlock_ok:

	ret = strnlen(buf, count);

unlock:

	mutex_unlock(&dynamic_netconsole_mutex);

	return ret;

}



CONFIGFS_ATTR(userdatum_, value);

CONFIGFS_ATTR(sysdata_, cpu_nr_enabled);



static struct configfs_attribute *userdatum_attrs[] = {

	&userdatum_attr_value,
@@ -853,6 +933,7 @@ static void userdatum_drop(struct config_group *group, struct config_item *item) 
}



static struct configfs_attribute *userdata_attrs[] = {

	&sysdata_attr_cpu_nr_enabled,

	NULL,

};