/*
* 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 <net/genetlink.h>
#include <asm/atomic.h>
static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
static int family_registered;
kmem_cache_t *taskstats_cache;
static DEFINE_MUTEX(taskstats_exit_mutex);
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 },
};
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;
}
static int send_reply(struct sk_buff *skb, pid_t pid, int event)
{
struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
void *reply;
int rc;
reply = genlmsg_data(genlhdr);
rc = genlmsg_end(skb, reply);
if (rc < 0) {
nlmsg_free(skb);
return rc;
}
if (event == TASKSTATS_MSG_MULTICAST)
return genlmsg_multicast(skb, pid, TASKSTATS_LISTEN_GROUP);
return genlmsg_unicast(skb, pid);
}
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;
*/
err:
put_task_struct(tsk);
return rc;
}
static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
struct taskstats *stats)
{
int rc;
struct task_struct *tsk, *first;
first = tgidtsk;
read_lock(&tasklist_lock);
if (!first) {
first = find_task_by_pid(tgid);
if (!first) {
read_unlock(&tasklist_lock);
return -ESRCH;
}
}
tsk = first;
do {
/*
* Each accounting subsystem adds calls its functions to
* fill in relevant parts of struct taskstsats as follows
*
* rc = per-task-foo(stats, tsk);
* if (rc)
* break;
*/
} while_each_thread(first, tsk);
read_unlock(&tasklist_lock);
/*
* Accounting subsytems can also add calls here if they don't
* wish to aggregate statistics for per-tgid stats
*/
return rc;
}
static int taskstats_send_stats(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;
/*
* 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, TASKSTATS_MSG_UNICAST);
nla_put_failure:
return genlmsg_cancel(rep_skb, reply);
err:
nlmsg_free(rep_skb);
return rc;
}
/* Send pid data out on exit */
void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
struct taskstats *tgidstats)
{
int rc;
struct sk_buff *rep_skb;
void *reply;
size_t size;
int is_thread_group;
struct nlattr *na;
if (!family_registered || !tidstats)
return;
mutex_lock(&taskstats_exit_mutex);
is_thread_group = !thread_group_empty(tsk);
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 || !tgidstats) {
send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
goto ret;
}
rc = fill_tgid(tsk->pid, tsk, tgidstats);
/*
* If fill_tgid() failed then one probable reason could be that the
* thread group leader has exited. fill_tgid() will fail, send out
* the pid statistics collected earlier.
*/
if (rc < 0) {
send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
goto ret;
}
na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
*tgidstats);
nla_nest_end(rep_skb, na);
send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
goto ret;
nla_put_failure:
genlmsg_cancel(rep_skb, reply);
goto ret;
err_skb:
nlmsg_free(rep_skb);
ret:
mutex_unlock(&taskstats_exit_mutex);
return;
}
static struct genl_ops taskstats_ops = {
.cmd = TASKSTATS_CMD_GET,
.doit = taskstats_send_stats,
.policy = taskstats_cmd_get_policy,
};
/* Needed early in initialization */
void __init taskstats_init_early(void)
{
taskstats_cache = kmem_cache_create("taskstats_cache",
sizeof(struct taskstats),
0, SLAB_PANIC, NULL, NULL);
}
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);
