/*
* 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/delayacct.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
*/
skb = nlmsg_new(size);
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 int 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, ret, delcount = 0;
rc = genlmsg_end(skb, reply);
if (rc < 0) {
nlmsg_free(skb);
return rc;
}
rc = 0;
listeners = &per_cpu(listener_array, cpu);
down_read(&listeners->sem);
list_for_each_entry_safe(s, tmp, &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) {
nlmsg_free(skb_cur);
rc = -ENOMEM;
break;
}
}
ret = genlmsg_unicast(skb_cur, s->pid);
if (ret == -ECONNREFUSED) {
s->valid = 0;
delcount++;
rc = ret;
}
skb_cur = skb_next;
}
up_read(&listeners->sem);
if (!delcount)
return rc;
/* 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);
return rc;
}
static int fill_pid(pid_t pid, struct task_struct *pidtsk,
struct taskstats *stats)
{
int rc;
struct task_struct *tsk = pidtsk;
if (!pidtsk) {
read_lock(&tasklist_lock);
tsk = find_task_by_pid(pid);
if (!tsk) {
read_unlock(&tasklist_lock);
return -ESRCH;
}
get_task_struct(tsk);
read_unlock(&tasklist_lock);
} else
get_task_struct(tsk);
/*
* Each accounting subsystem adds calls to its functions to
* fill in relevant parts of struct taskstsats as follows
*
* rc = per-task-foo(stats, tsk);
* if (rc)
* goto err;
*/
rc = delayacct_add_tsk(stats, tsk);
stats->version = TASKSTATS_VERSION;
/* Define err: label here if needed */
put_task_struct(tsk);
return rc;
}
static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
struct taskstats *stats)
{
struct task_struct *tsk, *first;
unsigned long flags;
/*
* Add additional stats from live tasks except zombie thread group
* leaders who are already counted with the dead tasks
*/
first = tgidtsk;
if (!first) {
read_lock(&tasklist_lock);
first = find_task_by_pid(tgid);
if (!first) {
read_unlock(&tasklist_lock);
return -ESRCH;
}
get_task_struct(first);
read_unlock(&tasklist_lock);
} else
get_task_struct(first);
/* Start with stats from dead tasks */
spin_lock_irqsave(&first->signal->stats_lock, flags);
if (first->signal->stats)
memcpy(stats, first->signal->stats, sizeof(*stats));
spin_unlock_irqrestore(&first->signal->stats_lock, flags);
tsk = first;
read_lock(&tasklist_lock);
do {
if (tsk->exit_state == EXIT_ZOMBIE && thread_group_leader(tsk))
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);
read_unlock(&tasklist_lock);
stats->version = TASKSTATS_VERSION;
/*
* Accounting subsytems can also add calls here to modify
* fields of taskstats.
*/
return 0;
}
static void fill_tgid_exit(struct task_struct *tsk)
{
unsigned long flags;
spin_lock_irqsave(&tsk->signal->stats_lock, 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->signal->stats_lock, 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:
return 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;
unsigned long flags;
if (!family_registered || !tidstats)
return;
spin_lock_irqsave(&tsk->signal->stats_lock, flags);
is_thread_group = tsk->signal->stats ? 1 : 0;
spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
rc = 0;
/*
* Size includes space for nested attributes
*/
size = nla_total_size(sizeof(u32)) +
nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
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);
goto ret;
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);
