[PATCH] taskstats: fill_stats_for_tgid: use for_each_thread()

[Oleg Nesterov <oleg@redhat.com>]

do/while_each_thread should be avoided when possible.

Plus I _think_ this change allows to avoid lock_task_sighand() but I am not
sure, I forgot everything about taskstats. In any case, this code does not
look right in that the same thread can be accounted twice: taskstats_exit()
can account the exiting thread in signal->stats and drop ->siglock but this
thread is still on the thread-group list, so lock_task_sighand() can't help.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 kernel/taskstats.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 8ce3fa0c19e2..4354ea231fab 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -233,9 +233,8 @@ static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 	else
 		memset(stats, 0, sizeof(*stats));
 
-	tsk = first;
 	start_time = ktime_get_ns();
-	do {
+	for_each_thread(first, tsk) {
 		if (tsk->exit_state)
 			continue;
 		/*
@@ -258,7 +257,7 @@ static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 
 		stats->nvcsw += tsk->nvcsw;
 		stats->nivcsw += tsk->nivcsw;
-	} while_each_thread(first, tsk);
+	}
 
 	unlock_task_sighand(first, &flags);
 	rc = 0;
-- 
2.25.1.362.g51ebf55