2 * taskstats.c - Export per-task statistics to userland
4 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
5 * (C) Balbir Singh, IBM Corp. 2006
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
19 #include <linux/kernel.h>
20 #include <linux/taskstats_kern.h>
21 #include <net/genetlink.h>
22 #include <asm/atomic.h>
24 static DEFINE_PER_CPU(__u32
, taskstats_seqnum
) = { 0 };
25 static int family_registered
;
26 kmem_cache_t
*taskstats_cache
;
27 static DEFINE_MUTEX(taskstats_exit_mutex
);
29 static struct genl_family family
= {
30 .id
= GENL_ID_GENERATE
,
31 .name
= TASKSTATS_GENL_NAME
,
32 .version
= TASKSTATS_GENL_VERSION
,
33 .maxattr
= TASKSTATS_CMD_ATTR_MAX
,
36 static struct nla_policy taskstats_cmd_get_policy
[TASKSTATS_CMD_ATTR_MAX
+1]
38 [TASKSTATS_CMD_ATTR_PID
] = { .type
= NLA_U32
},
39 [TASKSTATS_CMD_ATTR_TGID
] = { .type
= NLA_U32
},
43 static int prepare_reply(struct genl_info
*info
, u8 cmd
, struct sk_buff
**skbp
,
44 void **replyp
, size_t size
)
50 * If new attributes are added, please revisit this allocation
52 skb
= nlmsg_new(size
);
57 int seq
= get_cpu_var(taskstats_seqnum
)++;
58 put_cpu_var(taskstats_seqnum
);
60 reply
= genlmsg_put(skb
, 0, seq
,
64 reply
= genlmsg_put(skb
, info
->snd_pid
, info
->snd_seq
,
77 static int send_reply(struct sk_buff
*skb
, pid_t pid
, int event
)
79 struct genlmsghdr
*genlhdr
= nlmsg_data((struct nlmsghdr
*)skb
->data
);
83 reply
= genlmsg_data(genlhdr
);
85 rc
= genlmsg_end(skb
, reply
);
91 if (event
== TASKSTATS_MSG_MULTICAST
)
92 return genlmsg_multicast(skb
, pid
, TASKSTATS_LISTEN_GROUP
);
93 return genlmsg_unicast(skb
, pid
);
96 static int fill_pid(pid_t pid
, struct task_struct
*pidtsk
,
97 struct taskstats
*stats
)
100 struct task_struct
*tsk
= pidtsk
;
103 read_lock(&tasklist_lock
);
104 tsk
= find_task_by_pid(pid
);
106 read_unlock(&tasklist_lock
);
109 get_task_struct(tsk
);
110 read_unlock(&tasklist_lock
);
112 get_task_struct(tsk
);
115 * Each accounting subsystem adds calls to its functions to
116 * fill in relevant parts of struct taskstsats as follows
118 * rc = per-task-foo(stats, tsk);
124 put_task_struct(tsk
);
129 static int fill_tgid(pid_t tgid
, struct task_struct
*tgidtsk
,
130 struct taskstats
*stats
)
133 struct task_struct
*tsk
, *first
;
136 read_lock(&tasklist_lock
);
138 first
= find_task_by_pid(tgid
);
140 read_unlock(&tasklist_lock
);
147 * Each accounting subsystem adds calls its functions to
148 * fill in relevant parts of struct taskstsats as follows
150 * rc = per-task-foo(stats, tsk);
155 } while_each_thread(first
, tsk
);
156 read_unlock(&tasklist_lock
);
159 * Accounting subsytems can also add calls here if they don't
160 * wish to aggregate statistics for per-tgid stats
166 static int taskstats_send_stats(struct sk_buff
*skb
, struct genl_info
*info
)
169 struct sk_buff
*rep_skb
;
170 struct taskstats stats
;
176 * Size includes space for nested attributes
178 size
= nla_total_size(sizeof(u32
)) +
179 nla_total_size(sizeof(struct taskstats
)) + nla_total_size(0);
181 memset(&stats
, 0, sizeof(stats
));
182 rc
= prepare_reply(info
, TASKSTATS_CMD_NEW
, &rep_skb
, &reply
, size
);
186 if (info
->attrs
[TASKSTATS_CMD_ATTR_PID
]) {
187 u32 pid
= nla_get_u32(info
->attrs
[TASKSTATS_CMD_ATTR_PID
]);
188 rc
= fill_pid(pid
, NULL
, &stats
);
192 na
= nla_nest_start(rep_skb
, TASKSTATS_TYPE_AGGR_PID
);
193 NLA_PUT_U32(rep_skb
, TASKSTATS_TYPE_PID
, pid
);
194 NLA_PUT_TYPE(rep_skb
, struct taskstats
, TASKSTATS_TYPE_STATS
,
196 } else if (info
->attrs
[TASKSTATS_CMD_ATTR_TGID
]) {
197 u32 tgid
= nla_get_u32(info
->attrs
[TASKSTATS_CMD_ATTR_TGID
]);
198 rc
= fill_tgid(tgid
, NULL
, &stats
);
202 na
= nla_nest_start(rep_skb
, TASKSTATS_TYPE_AGGR_TGID
);
203 NLA_PUT_U32(rep_skb
, TASKSTATS_TYPE_TGID
, tgid
);
204 NLA_PUT_TYPE(rep_skb
, struct taskstats
, TASKSTATS_TYPE_STATS
,
211 nla_nest_end(rep_skb
, na
);
213 return send_reply(rep_skb
, info
->snd_pid
, TASKSTATS_MSG_UNICAST
);
216 return genlmsg_cancel(rep_skb
, reply
);
222 /* Send pid data out on exit */
223 void taskstats_exit_send(struct task_struct
*tsk
, struct taskstats
*tidstats
,
224 struct taskstats
*tgidstats
)
227 struct sk_buff
*rep_skb
;
233 if (!family_registered
|| !tidstats
)
236 mutex_lock(&taskstats_exit_mutex
);
238 is_thread_group
= !thread_group_empty(tsk
);
242 * Size includes space for nested attributes
244 size
= nla_total_size(sizeof(u32
)) +
245 nla_total_size(sizeof(struct taskstats
)) + nla_total_size(0);
248 size
= 2 * size
; /* PID + STATS + TGID + STATS */
250 rc
= prepare_reply(NULL
, TASKSTATS_CMD_NEW
, &rep_skb
, &reply
, size
);
254 rc
= fill_pid(tsk
->pid
, tsk
, tidstats
);
258 na
= nla_nest_start(rep_skb
, TASKSTATS_TYPE_AGGR_PID
);
259 NLA_PUT_U32(rep_skb
, TASKSTATS_TYPE_PID
, (u32
)tsk
->pid
);
260 NLA_PUT_TYPE(rep_skb
, struct taskstats
, TASKSTATS_TYPE_STATS
,
262 nla_nest_end(rep_skb
, na
);
264 if (!is_thread_group
|| !tgidstats
) {
265 send_reply(rep_skb
, 0, TASKSTATS_MSG_MULTICAST
);
269 rc
= fill_tgid(tsk
->pid
, tsk
, tgidstats
);
271 * If fill_tgid() failed then one probable reason could be that the
272 * thread group leader has exited. fill_tgid() will fail, send out
273 * the pid statistics collected earlier.
276 send_reply(rep_skb
, 0, TASKSTATS_MSG_MULTICAST
);
280 na
= nla_nest_start(rep_skb
, TASKSTATS_TYPE_AGGR_TGID
);
281 NLA_PUT_U32(rep_skb
, TASKSTATS_TYPE_TGID
, (u32
)tsk
->tgid
);
282 NLA_PUT_TYPE(rep_skb
, struct taskstats
, TASKSTATS_TYPE_STATS
,
284 nla_nest_end(rep_skb
, na
);
286 send_reply(rep_skb
, 0, TASKSTATS_MSG_MULTICAST
);
290 genlmsg_cancel(rep_skb
, reply
);
295 mutex_unlock(&taskstats_exit_mutex
);
299 static struct genl_ops taskstats_ops
= {
300 .cmd
= TASKSTATS_CMD_GET
,
301 .doit
= taskstats_send_stats
,
302 .policy
= taskstats_cmd_get_policy
,
305 /* Needed early in initialization */
306 void __init
taskstats_init_early(void)
308 taskstats_cache
= kmem_cache_create("taskstats_cache",
309 sizeof(struct taskstats
),
310 0, SLAB_PANIC
, NULL
, NULL
);
313 static int __init
taskstats_init(void)
317 rc
= genl_register_family(&family
);
321 rc
= genl_register_ops(&family
, &taskstats_ops
);
325 family_registered
= 1;
328 genl_unregister_family(&family
);
333 * late initcall ensures initialization of statistics collection
334 * mechanisms precedes initialization of the taskstats interface
336 late_initcall(taskstats_init
);