1 files changed, 336 insertions, 0 deletions
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
new file mode 100644
index 00000000000..82ec9137d90
--- /dev/null
+++ b/kernel/taskstats.c
@@ -0,0 +1,336 @@
+/*
+ * 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);