Threads also have an exit code on their own, so report it in
TASKSTATS_CMD_ATTR_PID.

For TASKSTATS_CMD_ATTR_TGID, instead of relying only on the exit code of the
leader, we use task->signal->group_exit_code if not null as suggested by
Oleg Nesterov.

Also, document that as of this patch, fill_threadgroup_stats() must be called
after add_tsk_stats() as it may overwrite some stats.

Signed-off-by: Guillaume Chazarain
Cc: Balbir Singh
Cc: Jay Lan
Cc: Jonathan Lim
Cc: Oleg Nesterov
---

kernel/taskstats.c | 2 ++
kernel/tsacct.c | 12 +++++++-----
2 files changed, 9 insertions(+), 5 deletions(-)


diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 59fe1d8..938c0b0 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -208,6 +208,8 @@ static void add_tsk_stats(struct taskstats *stats, struct task_struct *task)
*
* Will be called on the thread group leader if requesting stats for the whole
* thread group.
+ * fill_threadgroup_stats() may overwrite stats from add_tsk_stats(), so it
+ * must be called after add_tsk_stats().
*/
static void fill_threadgroup_stats(struct taskstats *stats,
struct task_struct *task, bool tg_stats)
diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index 8c2f470..e83f53b 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -65,13 +65,15 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
void bacct_fill_threadgroup(struct taskstats *stats, struct task_struct *tsk,
bool tg_stats)
{
+ int group_exit_code;
+
fill_wall_times(stats, tsk);

- if (thread_group_leader(tsk)) {
- stats->ac_exitcode = tsk->exit_code;
- if (tsk->flags & PF_FORKNOEXEC)
- stats->ac_flag |= AFORK;
- }
+ if (thread_group_leader(tsk) && ((tsk->flags & PF_FORKNOEXEC)))
+ stats->ac_flag |= AFORK;
+
+ group_exit_code = tg_stats ? tsk->signal->group_exit_code : 0;
+ stats->ac_exitcode = group_exit_code ? : tsk->exit_code;

stats->ac_nice = task_nice(tsk);
stats->ac_sched = tsk->policy;
-
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