kernel/taskstats.c - linux/kernel/git/klassert/ipsec - Git at Google

 /*
  * taskstats.c - Export per-task statistics to userland
  *
  * Copyright (C) Shailabh Nagar, IBM Corp. 2006
  *           (C) Balbir Singh,   IBM Corp. 2006
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  */

 #include <linux/kernel.h>
 #include <linux/taskstats_kern.h>
 #include <linux/tsacct_kern.h>
 #include <linux/delayacct.h>
 #include <linux/tsacct_kern.h>
 #include <linux/cpumask.h>
 #include <linux/percpu.h>
 #include <net/genetlink.h>
 #include <asm/atomic.h>

 /*
  * Maximum length of a cpumask that can be specified in
  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
  */
 #define TASKSTATS_CPUMASK_MAXLEN	(100+6*NR_CPUS)

 static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
 static int family_registered;
 kmem_cache_t *taskstats_cache;

 static struct genl_family family = {
 	.id		= GENL_ID_GENERATE,
 	.name		= TASKSTATS_GENL_NAME,
 	.version	= TASKSTATS_GENL_VERSION,
 	.maxattr	= TASKSTATS_CMD_ATTR_MAX,
 };

 static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
 __read_mostly = {
 	[TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
 	[TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
 	[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
 	[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};

 struct listener {
 	struct list_head list;
 	pid_t pid;
 	char valid;
 };

 struct listener_list {
 	struct rw_semaphore sem;
 	struct list_head list;
 };
 static DEFINE_PER_CPU(struct listener_list, listener_array);

 enum actions {
 	REGISTER,
 	DEREGISTER,
 	CPU_DONT_CARE
 };

 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
 			void **replyp, size_t size)
 {
 	struct sk_buff *skb;
 	void *reply;

 	/*
 	 * If new attributes are added, please revisit this allocation
 	 */
 	size = nlmsg_total_size(genlmsg_total_size(size));
 	skb = nlmsg_new(size, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;

 	if (!info) {
 		int seq = get_cpu_var(taskstats_seqnum)++;
 		put_cpu_var(taskstats_seqnum);

 		reply = genlmsg_put(skb, 0, seq,
 				family.id, 0, 0,
 				cmd, family.version);
 	} else
 		reply = genlmsg_put(skb, info->snd_pid, info->snd_seq,
 				family.id, 0, 0,
 				cmd, family.version);
 	if (reply == NULL) {
 		nlmsg_free(skb);
 		return -EINVAL;
 	}

 	*skbp = skb;
 	*replyp = reply;
 	return 0;
 }

 /*
  * Send taskstats data in @skb to listener with nl_pid @pid
  */
 static int send_reply(struct sk_buff *skb, pid_t pid)
 {
 	struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 	void *reply = genlmsg_data(genlhdr);
 	int rc;

 	rc = genlmsg_end(skb, reply);
 	if (rc < 0) {
 		nlmsg_free(skb);
 		return rc;
 	}

 	return genlmsg_unicast(skb, pid);
 }

 /*
  * Send taskstats data in @skb to listeners registered for @cpu's exit data
  */
 static void send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
 {
 	struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 	struct listener_list *listeners;
 	struct listener *s, *tmp;
 	struct sk_buff *skb_next, *skb_cur = skb;
 	void *reply = genlmsg_data(genlhdr);
 	int rc, delcount = 0;

 	rc = genlmsg_end(skb, reply);
 	if (rc < 0) {
 		nlmsg_free(skb);
 		return;
 	}

 	rc = 0;
 	listeners = &per_cpu(listener_array, cpu);
 	down_read(&listeners->sem);
 	list_for_each_entry(s, &listeners->list, list) {
 		skb_next = NULL;
 		if (!list_is_last(&s->list, &listeners->list)) {
 			skb_next = skb_clone(skb_cur, GFP_KERNEL);
 			if (!skb_next)
 				break;
 		}
 		rc = genlmsg_unicast(skb_cur, s->pid);
 		if (rc == -ECONNREFUSED) {
 			s->valid = 0;
 			delcount++;
 		}
 		skb_cur = skb_next;
 	}
 	up_read(&listeners->sem);

 	if (skb_cur)
 		nlmsg_free(skb_cur);

 	if (!delcount)
 		return;

 	/* Delete invalidated entries */
 	down_write(&listeners->sem);
 	list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 		if (!s->valid) {
 			list_del(&s->list);
 			kfree(s);
 		}
 	}
 	up_write(&listeners->sem);
 }

 static int fill_pid(pid_t pid, struct task_struct *tsk,
 		struct taskstats *stats)
 {
 	int rc = 0;

 	if (!tsk) {
 		rcu_read_lock();
 		tsk = find_task_by_pid(pid);
 		if (tsk)
 			get_task_struct(tsk);
 		rcu_read_unlock();
 		if (!tsk)
 			return -ESRCH;
 	} else
 		get_task_struct(tsk);

 	/*
 	 * Each accounting subsystem adds calls to its functions to
 	 * fill in relevant parts of struct taskstsats as follows
 	 *
 	 *	per-task-foo(stats, tsk);
 	 */

 	delayacct_add_tsk(stats, tsk);

 	/* fill in basic acct fields */
 	stats->version = TASKSTATS_VERSION;
 	bacct_add_tsk(stats, tsk);

 	/* fill in extended acct fields */
 	xacct_add_tsk(stats, tsk);

 	/* Define err: label here if needed */
 	put_task_struct(tsk);
 	return rc;

 }

 static int fill_tgid(pid_t tgid, struct task_struct *first,
 		struct taskstats *stats)
 {
 	struct task_struct *tsk;
 	unsigned long flags;
 	int rc = -ESRCH;

 	/*
 	 * Add additional stats from live tasks except zombie thread group
 	 * leaders who are already counted with the dead tasks
 	 */
 	rcu_read_lock();
 	if (!first)
 		first = find_task_by_pid(tgid);

 	if (!first || !lock_task_sighand(first, &flags))
 		goto out;

 	if (first->signal->stats)
 		memcpy(stats, first->signal->stats, sizeof(*stats));

 	tsk = first;
 	do {
 		if (tsk->exit_state)
 			continue;
 		/*
 		 * Accounting subsystem can call its functions here to
 		 * fill in relevant parts of struct taskstsats as follows
 		 *
 		 *	per-task-foo(stats, tsk);
 		 */
 		delayacct_add_tsk(stats, tsk);

 	} while_each_thread(first, tsk);

 	unlock_task_sighand(first, &flags);
 	rc = 0;
 out:
 	rcu_read_unlock();

 	stats->version = TASKSTATS_VERSION;
 	/*
 	 * Accounting subsytems can also add calls here to modify
 	 * fields of taskstats.
 	 */
 	return rc;
 }


 static void fill_tgid_exit(struct task_struct *tsk)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
 	if (!tsk->signal->stats)
 		goto ret;

 	/*
 	 * Each accounting subsystem calls its functions here to
 	 * accumalate its per-task stats for tsk, into the per-tgid structure
 	 *
 	 *	per-task-foo(tsk->signal->stats, tsk);
 	 */
 	delayacct_add_tsk(tsk->signal->stats, tsk);
 ret:
 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 	return;
 }

 static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
 {
 	struct listener_list *listeners;
 	struct listener *s, *tmp;
 	unsigned int cpu;
 	cpumask_t mask = *maskp;

 	if (!cpus_subset(mask, cpu_possible_map))
 		return -EINVAL;

 	if (isadd == REGISTER) {
 		for_each_cpu_mask(cpu, mask) {
 			s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
 					 cpu_to_node(cpu));
 			if (!s)
 				goto cleanup;
 			s->pid = pid;
 			INIT_LIST_HEAD(&s->list);
 			s->valid = 1;

 			listeners = &per_cpu(listener_array, cpu);
 			down_write(&listeners->sem);
 			list_add(&s->list, &listeners->list);
 			up_write(&listeners->sem);
 		}
 		return 0;
 	}

 	/* Deregister or cleanup */
 cleanup:
 	for_each_cpu_mask(cpu, mask) {
 		listeners = &per_cpu(listener_array, cpu);
 		down_write(&listeners->sem);
 		list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 			if (s->pid == pid) {
 				list_del(&s->list);
 				kfree(s);
 				break;
 			}
 		}
 		up_write(&listeners->sem);
 	}
 	return 0;
 }

 static int parse(struct nlattr *na, cpumask_t *mask)
 {
 	char *data;
 	int len;
 	int ret;

 	if (na == NULL)
 		return 1;
 	len = nla_len(na);
 	if (len > TASKSTATS_CPUMASK_MAXLEN)
 		return -E2BIG;
 	if (len < 1)
 		return -EINVAL;
 	data = kmalloc(len, GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 	nla_strlcpy(data, na, len);
 	ret = cpulist_parse(data, *mask);
 	kfree(data);
 	return ret;
 }

 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 {
 	int rc = 0;
 	struct sk_buff *rep_skb;
 	struct taskstats stats;
 	void *reply;
 	size_t size;
 	struct nlattr *na;
 	cpumask_t mask;

 	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
 	if (rc < 0)
 		return rc;
 	if (rc == 0)
 		return add_del_listener(info->snd_pid, &mask, REGISTER);

 	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
 	if (rc < 0)
 		return rc;
 	if (rc == 0)
 		return add_del_listener(info->snd_pid, &mask, DEREGISTER);

 	/*
 	 * Size includes space for nested attributes
 	 */
 	size = nla_total_size(sizeof(u32)) +
 		nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);

 	memset(&stats, 0, sizeof(stats));
 	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 	if (rc < 0)
 		return rc;

 	if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
 		u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 		rc = fill_pid(pid, NULL, &stats);
 		if (rc < 0)
 			goto err;

 		na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 		NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
 		NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 				stats);
 	} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
 		u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 		rc = fill_tgid(tgid, NULL, &stats);
 		if (rc < 0)
 			goto err;

 		na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 		NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 		NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 				stats);
 	} else {
 		rc = -EINVAL;
 		goto err;
 	}

 	nla_nest_end(rep_skb, na);

 	return send_reply(rep_skb, info->snd_pid);

 nla_put_failure:
 	rc = genlmsg_cancel(rep_skb, reply);
 err:
 	nlmsg_free(rep_skb);
 	return rc;
 }

 void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
 {
 	struct listener_list *listeners;
 	struct taskstats *tmp;
 	/*
 	 * This is the cpu on which the task is exiting currently and will
 	 * be the one for which the exit event is sent, even if the cpu
 	 * on which this function is running changes later.
 	 */
 	*mycpu = raw_smp_processor_id();

 	*ptidstats = NULL;
 	tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
 	if (!tmp)
 		return;

 	listeners = &per_cpu(listener_array, *mycpu);
 	down_read(&listeners->sem);
 	if (!list_empty(&listeners->list)) {
 		*ptidstats = tmp;
 		tmp = NULL;
 	}
 	up_read(&listeners->sem);
 	kfree(tmp);
 }

 /* Send pid data out on exit */
 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
 			int group_dead, unsigned int mycpu)
 {
 	int rc;
 	struct sk_buff *rep_skb;
 	void *reply;
 	size_t size;
 	int is_thread_group;
 	struct nlattr *na;

 	if (!family_registered || !tidstats)
 		return;

 	rc = 0;
 	/*
 	 * Size includes space for nested attributes
 	 */
 	size = nla_total_size(sizeof(u32)) +
 		nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);

 	is_thread_group = (tsk->signal->stats != NULL);
 	if (is_thread_group)
 		size = 2 * size;	/* PID + STATS + TGID + STATS */

 	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 	if (rc < 0)
 		goto ret;

 	rc = fill_pid(tsk->pid, tsk, tidstats);
 	if (rc < 0)
 		goto err_skb;

 	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
 	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 			*tidstats);
 	nla_nest_end(rep_skb, na);

 	if (!is_thread_group)
 		goto send;

 	/*
 	 * tsk has/had a thread group so fill the tsk->signal->stats structure
 	 * Doesn't matter if tsk is the leader or the last group member leaving
 	 */

 	fill_tgid_exit(tsk);
 	if (!group_dead)
 		goto send;

 	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
 	/* No locking needed for tsk->signal->stats since group is dead */
 	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 			*tsk->signal->stats);
 	nla_nest_end(rep_skb, na);

 send:
 	send_cpu_listeners(rep_skb, mycpu);
 	return;

 nla_put_failure:
 	genlmsg_cancel(rep_skb, reply);
 err_skb:
 	nlmsg_free(rep_skb);
 ret:
 	return;
 }

 static struct genl_ops taskstats_ops = {
 	.cmd		= TASKSTATS_CMD_GET,
 	.doit		= taskstats_user_cmd,
 	.policy		= taskstats_cmd_get_policy,
 };

 /* Needed early in initialization */
 void __init taskstats_init_early(void)
 {
 	unsigned int i;

 	taskstats_cache = kmem_cache_create("taskstats_cache",
 						sizeof(struct taskstats),
 						0, SLAB_PANIC, NULL, NULL);
 	for_each_possible_cpu(i) {
 		INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 		init_rwsem(&(per_cpu(listener_array, i).sem));
 	}
 }

 static int __init taskstats_init(void)
 {
 	int rc;

 	rc = genl_register_family(&family);
 	if (rc)
 		return rc;

 	rc = genl_register_ops(&family, &taskstats_ops);
 	if (rc < 0)
 		goto err;

 	family_registered = 1;
 	return 0;
 err:
 	genl_unregister_family(&family);
 	return rc;
 }

 /*
  * late initcall ensures initialization of statistics collection
  * mechanisms precedes initialization of the taskstats interface
  */
 late_initcall(taskstats_init);
	/*
	* taskstats.c - Export per-task statistics to userland
	*
	* Copyright (C) Shailabh Nagar, IBM Corp. 2006
	* (C) Balbir Singh, IBM Corp. 2006
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/taskstats_kern.h>
	#include <linux/tsacct_kern.h>
	#include <linux/delayacct.h>
	#include <linux/tsacct_kern.h>
	#include <linux/cpumask.h>
	#include <linux/percpu.h>
	#include <net/genetlink.h>
	#include <asm/atomic.h>

	/*
	* Maximum length of a cpumask that can be specified in
	* the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
	*/
	#define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)

	static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
	static int family_registered;
	kmem_cache_t *taskstats_cache;

	static struct genl_family family = {
	.id = GENL_ID_GENERATE,
	.name = TASKSTATS_GENL_NAME,
	.version = TASKSTATS_GENL_VERSION,
	.maxattr = TASKSTATS_CMD_ATTR_MAX,
	};

	static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
	__read_mostly = {
	[TASKSTATS_CMD_ATTR_PID] = { .type = NLA_U32 },
	[TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
	[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
	[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};

	struct listener {
	struct list_head list;
	pid_t pid;
	char valid;
	};

	struct listener_list {
	struct rw_semaphore sem;
	struct list_head list;
	};
	static DEFINE_PER_CPU(struct listener_list, listener_array);

	enum actions {
	REGISTER,
	DEREGISTER,
	CPU_DONT_CARE
	};

	static int prepare_reply(struct genl_info info, u8 cmd, struct sk_buff *skbp,
	void **replyp, size_t size)
	{
	struct sk_buff *skb;
	void *reply;

	/*
	* If new attributes are added, please revisit this allocation
	*/
	size = nlmsg_total_size(genlmsg_total_size(size));
	skb = nlmsg_new(size, GFP_KERNEL);
	if (!skb)
	return -ENOMEM;

	if (!info) {
	int seq = get_cpu_var(taskstats_seqnum)++;
	put_cpu_var(taskstats_seqnum);

	reply = genlmsg_put(skb, 0, seq,
	family.id, 0, 0,
	cmd, family.version);
	} else
	reply = genlmsg_put(skb, info->snd_pid, info->snd_seq,
	family.id, 0, 0,
	cmd, family.version);
	if (reply == NULL) {
	nlmsg_free(skb);
	return -EINVAL;
	}

	*skbp = skb;
	*replyp = reply;
	return 0;
	}

	/*
	* Send taskstats data in @skb to listener with nl_pid @pid
	*/
	static int send_reply(struct sk_buff *skb, pid_t pid)
	{
	struct genlmsghdr genlhdr = nlmsg_data((struct nlmsghdr )skb->data);
	void *reply = genlmsg_data(genlhdr);
	int rc;

	rc = genlmsg_end(skb, reply);
	if (rc < 0) {
	nlmsg_free(skb);
	return rc;
	}

	return genlmsg_unicast(skb, pid);
	}

	/*
	* Send taskstats data in @skb to listeners registered for @cpu's exit data
	*/
	static void send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
	{
	struct genlmsghdr genlhdr = nlmsg_data((struct nlmsghdr )skb->data);
	struct listener_list *listeners;
	struct listener s, tmp;
	struct sk_buff skb_next, skb_cur = skb;
	void *reply = genlmsg_data(genlhdr);
	int rc, delcount = 0;

	rc = genlmsg_end(skb, reply);
	if (rc < 0) {
	nlmsg_free(skb);
	return;
	}

	rc = 0;
	listeners = &per_cpu(listener_array, cpu);
	down_read(&listeners->sem);
	list_for_each_entry(s, &listeners->list, list) {
	skb_next = NULL;
	if (!list_is_last(&s->list, &listeners->list)) {
	skb_next = skb_clone(skb_cur, GFP_KERNEL);
	if (!skb_next)
	break;
	}
	rc = genlmsg_unicast(skb_cur, s->pid);
	if (rc == -ECONNREFUSED) {
	s->valid = 0;
	delcount++;
	}
	skb_cur = skb_next;
	}
	up_read(&listeners->sem);

	if (skb_cur)
	nlmsg_free(skb_cur);

	if (!delcount)
	return;

	/* Delete invalidated entries */
	down_write(&listeners->sem);
	list_for_each_entry_safe(s, tmp, &listeners->list, list) {
	if (!s->valid) {
	list_del(&s->list);
	kfree(s);
	}
	}
	up_write(&listeners->sem);
	}

	static int fill_pid(pid_t pid, struct task_struct *tsk,
	struct taskstats *stats)
	{
	int rc = 0;

	if (!tsk) {
	rcu_read_lock();
	tsk = find_task_by_pid(pid);
	if (tsk)
	get_task_struct(tsk);
	rcu_read_unlock();
	if (!tsk)
	return -ESRCH;
	} else
	get_task_struct(tsk);

	/*
	* Each accounting subsystem adds calls to its functions to
	* fill in relevant parts of struct taskstsats as follows
	*
	* per-task-foo(stats, tsk);
	*/

	delayacct_add_tsk(stats, tsk);

	/* fill in basic acct fields */
	stats->version = TASKSTATS_VERSION;
	bacct_add_tsk(stats, tsk);

	/* fill in extended acct fields */
	xacct_add_tsk(stats, tsk);

	/* Define err: label here if needed */
	put_task_struct(tsk);
	return rc;

	}

	static int fill_tgid(pid_t tgid, struct task_struct *first,
	struct taskstats *stats)
	{
	struct task_struct *tsk;
	unsigned long flags;
	int rc = -ESRCH;

	/*
	* Add additional stats from live tasks except zombie thread group
	* leaders who are already counted with the dead tasks
	*/
	rcu_read_lock();
	if (!first)
	first = find_task_by_pid(tgid);

	if (!first \|\| !lock_task_sighand(first, &flags))
	goto out;

	if (first->signal->stats)
	memcpy(stats, first->signal->stats, sizeof(*stats));

	tsk = first;
	do {
	if (tsk->exit_state)
	continue;
	/*
	* Accounting subsystem can call its functions here to
	* fill in relevant parts of struct taskstsats as follows
	*
	* per-task-foo(stats, tsk);
	*/
	delayacct_add_tsk(stats, tsk);

	} while_each_thread(first, tsk);

	unlock_task_sighand(first, &flags);
	rc = 0;
	out:
	rcu_read_unlock();

	stats->version = TASKSTATS_VERSION;
	/*
	* Accounting subsytems can also add calls here to modify
	* fields of taskstats.
	*/
	return rc;
	}


	static void fill_tgid_exit(struct task_struct *tsk)
	{
	unsigned long flags;

	spin_lock_irqsave(&tsk->sighand->siglock, flags);
	if (!tsk->signal->stats)
	goto ret;

	/*
	* Each accounting subsystem calls its functions here to
	* accumalate its per-task stats for tsk, into the per-tgid structure
	*
	* per-task-foo(tsk->signal->stats, tsk);
	*/
	delayacct_add_tsk(tsk->signal->stats, tsk);
	ret:
	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
	return;
	}

	static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
	{
	struct listener_list *listeners;
	struct listener s, tmp;
	unsigned int cpu;
	cpumask_t mask = *maskp;

	if (!cpus_subset(mask, cpu_possible_map))
	return -EINVAL;

	if (isadd == REGISTER) {
	for_each_cpu_mask(cpu, mask) {
	s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
	cpu_to_node(cpu));
	if (!s)
	goto cleanup;
	s->pid = pid;
	INIT_LIST_HEAD(&s->list);
	s->valid = 1;

	listeners = &per_cpu(listener_array, cpu);
	down_write(&listeners->sem);
	list_add(&s->list, &listeners->list);
	up_write(&listeners->sem);
	}
	return 0;
	}

	/* Deregister or cleanup */
	cleanup:
	for_each_cpu_mask(cpu, mask) {
	listeners = &per_cpu(listener_array, cpu);
	down_write(&listeners->sem);
	list_for_each_entry_safe(s, tmp, &listeners->list, list) {
	if (s->pid == pid) {
	list_del(&s->list);
	kfree(s);
	break;
	}
	}
	up_write(&listeners->sem);
	}
	return 0;
	}

	static int parse(struct nlattr na, cpumask_t mask)
	{
	char *data;
	int len;
	int ret;

	if (na == NULL)
	return 1;
	len = nla_len(na);
	if (len > TASKSTATS_CPUMASK_MAXLEN)
	return -E2BIG;
	if (len < 1)
	return -EINVAL;
	data = kmalloc(len, GFP_KERNEL);
	if (!data)
	return -ENOMEM;
	nla_strlcpy(data, na, len);
	ret = cpulist_parse(data, *mask);
	kfree(data);
	return ret;
	}

	static int taskstats_user_cmd(struct sk_buff skb, struct genl_info info)
	{
	int rc = 0;
	struct sk_buff *rep_skb;
	struct taskstats stats;
	void *reply;
	size_t size;
	struct nlattr *na;
	cpumask_t mask;

	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
	if (rc < 0)
	return rc;
	if (rc == 0)
	return add_del_listener(info->snd_pid, &mask, REGISTER);

	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
	if (rc < 0)
	return rc;
	if (rc == 0)
	return add_del_listener(info->snd_pid, &mask, DEREGISTER);

	/*
	* Size includes space for nested attributes
	*/
	size = nla_total_size(sizeof(u32)) +
	nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);

	memset(&stats, 0, sizeof(stats));
	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
	if (rc < 0)
	return rc;

	if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
	u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
	rc = fill_pid(pid, NULL, &stats);
	if (rc < 0)
	goto err;

	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
	stats);
	} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
	u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
	rc = fill_tgid(tgid, NULL, &stats);
	if (rc < 0)
	goto err;

	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
	stats);
	} else {
	rc = -EINVAL;
	goto err;
	}

	nla_nest_end(rep_skb, na);

	return send_reply(rep_skb, info->snd_pid);

	nla_put_failure:
	rc = genlmsg_cancel(rep_skb, reply);
	err:
	nlmsg_free(rep_skb);
	return rc;
	}

	void taskstats_exit_alloc(struct taskstats *ptidstats, unsigned int mycpu)
	{
	struct listener_list *listeners;
	struct taskstats *tmp;
	/*
	* This is the cpu on which the task is exiting currently and will
	* be the one for which the exit event is sent, even if the cpu
	* on which this function is running changes later.
	*/
	*mycpu = raw_smp_processor_id();

	*ptidstats = NULL;
	tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
	if (!tmp)
	return;

	listeners = &per_cpu(listener_array, *mycpu);
	down_read(&listeners->sem);
	if (!list_empty(&listeners->list)) {
	*ptidstats = tmp;
	tmp = NULL;
	}
	up_read(&listeners->sem);
	kfree(tmp);
	}

	/* Send pid data out on exit */
	void taskstats_exit_send(struct task_struct tsk, struct taskstats tidstats,
	int group_dead, unsigned int mycpu)
	{
	int rc;
	struct sk_buff *rep_skb;
	void *reply;
	size_t size;
	int is_thread_group;
	struct nlattr *na;

	if (!family_registered \|\| !tidstats)
	return;

	rc = 0;
	/*
	* Size includes space for nested attributes
	*/
	size = nla_total_size(sizeof(u32)) +
	nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);

	is_thread_group = (tsk->signal->stats != NULL);
	if (is_thread_group)
	size = 2 * size; /* PID + STATS + TGID + STATS */

	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
	if (rc < 0)
	goto ret;

	rc = fill_pid(tsk->pid, tsk, tidstats);
	if (rc < 0)
	goto err_skb;

	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
	*tidstats);
	nla_nest_end(rep_skb, na);

	if (!is_thread_group)
	goto send;

	/*
	* tsk has/had a thread group so fill the tsk->signal->stats structure
	* Doesn't matter if tsk is the leader or the last group member leaving
	*/

	fill_tgid_exit(tsk);
	if (!group_dead)
	goto send;

	na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
	NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
	/* No locking needed for tsk->signal->stats since group is dead */
	NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
	*tsk->signal->stats);
	nla_nest_end(rep_skb, na);

	send:
	send_cpu_listeners(rep_skb, mycpu);
	return;

	nla_put_failure:
	genlmsg_cancel(rep_skb, reply);
	err_skb:
	nlmsg_free(rep_skb);
	ret:
	return;
	}

	static struct genl_ops taskstats_ops = {
	.cmd = TASKSTATS_CMD_GET,
	.doit = taskstats_user_cmd,
	.policy = taskstats_cmd_get_policy,
	};

	/* Needed early in initialization */
	void __init taskstats_init_early(void)
	{
	unsigned int i;

	taskstats_cache = kmem_cache_create("taskstats_cache",
	sizeof(struct taskstats),
	0, SLAB_PANIC, NULL, NULL);
	for_each_possible_cpu(i) {
	INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
	init_rwsem(&(per_cpu(listener_array, i).sem));
	}
	}

	static int __init taskstats_init(void)
	{
	int rc;

	rc = genl_register_family(&family);
	if (rc)
	return rc;

	rc = genl_register_ops(&family, &taskstats_ops);
	if (rc < 0)
	goto err;

	family_registered = 1;
	return 0;
	err:
	genl_unregister_family(&family);
	return rc;
	}

	/*
	* late initcall ensures initialization of statistics collection
	* mechanisms precedes initialization of the taskstats interface
	*/
	late_initcall(taskstats_init);