1 files changed, 66 insertions, 32 deletions

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index ea9506de3b85..4a0a5022b299 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -132,46 +132,79 @@ static int fill_pid(pid_t pid, struct task_struct *pidtsk,
 static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
                 struct taskstats *stats)
 {
-        int rc;
         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;
-        read_lock(&tasklist_lock);
         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;
                 /*
-                 * Each accounting subsystem adds calls its functions to
+                 * Accounting subsystem can call its functions here to
                  * fill in relevant parts of struct taskstsats as follows
                  *
-                 *      rc = per-task-foo(stats, tsk);
-                 *      if (rc)
-                 *              break;
+                 *      per-task-foo(stats, tsk);
                  */
-
-                rc = delayacct_add_tsk(stats, tsk);
-                if (rc)
-                        break;
+                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 if they don't
-         * wish to aggregate statistics for per-tgid stats
+         * Accounting subsytems can also add calls here to modify
+         * fields of taskstats.
          */
 
-        return rc;
+        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 taskstats_send_stats(struct sk_buff *skb, struct genl_info *info)
 {
         int rc = 0;
@@ -230,7 +263,7 @@ err:
 
 /* Send pid data out on exit */
 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
-                        struct taskstats *tgidstats)
+                        int group_dead)
 {
         int rc;
         struct sk_buff *rep_skb;
@@ -238,13 +271,16 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
         size_t size;
         int is_thread_group;
         struct nlattr *na;
+        unsigned long flags;
 
         if (!family_registered || !tidstats)
                 return;
 
-        is_thread_group = !thread_group_empty(tsk);
-        rc = 0;
+        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
          */
@@ -268,30 +304,28 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
                         *tidstats);
         nla_nest_end(rep_skb, na);
 
-        if (!is_thread_group || !tgidstats) {
-                send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
-                goto ret;
-        }
+        if (!is_thread_group)
+                goto send;
 
-        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.
+         * 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
          */
-        if (rc < 0) {
-                send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
-                goto ret;
-        }
+
+        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,
-                        *tgidstats);
+                        *tsk->signal->stats);
         nla_nest_end(rep_skb, na);
 
+send:
         send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
-        goto ret;
+        return;
 
 nla_put_failure:
         genlmsg_cancel(rep_skb, reply);