1 files changed, 568 insertions, 0 deletions

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
new file mode 100644
index 000000000000..f45179ce028e
--- /dev/null
+++ b/kernel/taskstats.c
@@ -0,0 +1,568 @@
+/*
+ * 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);