[PATCH] taskstats: fix sub-threads accounting

Oleg Nesterov
2006-10-30T21:38:09Z

If there are no listeners, taskstats_exit_send() just returns because
taskstats_exit_alloc() didn't allocate *tidstats. This is wrong, each
sub-thread should do fill_tgid_exit() on exit, otherwise its ->delays
is not recorded in ->signal->stats and lost.

Q: We don't send TASKSTATS_TYPE_AGGR_TGID when single-threaded process
exits. Is it good? How can the listener figure out that it was actually
a process exit, not sub-thread?

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- STATS/kernel/taskstats.c~2_send 2006-10-30 23:47:46.000000000 +0300
+++ STATS/kernel/taskstats.c 2006-10-31 00:14:42.000000000 +0300
@@ -446,10 +446,9 @@ void taskstats_exit_send(struct task_str
int is_thread_group;
struct nlattr *na;

- if (!family_registered || !tidstats)
+ if (!family_registered)
return;

- rc = 0;
/*
* Size includes space for nested attributes
*/
@@ -457,8 +456,15 @@ void taskstats_exit_send(struct task_str
nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);

is_thread_group = (tsk->signal->stats != NULL);
- if (is_thread_group)
- size = 2 * size; /* PID + STATS + TGID + STATS */
+ if (is_thread_group) {
+ /* PID + STATS + TGID + STATS */
+ size = 2 * size;
+ /* fill the tsk->signal->stats structure */
+ fill_tgid_exit(tsk);
+ }
+
+ if (!tidstats)
+ return;

rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
if (rc < 0)
@@ -478,11 +484,8 @@ void taskstats_exit_send(struct task_str
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;