From ed5378a387fd7c382497f2abcf4605e030b64044 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 9 Sep 2023 23:49:51 +0200 Subject: [PATCH] taskstats: fill_stats_for_tgid: use for_each_thread() 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. Link: https://lkml.kernel.org/r/20230909214951.GA24274@redhat.com Signed-off-by: Oleg Nesterov Cc: Eric W. Biederman Signed-off-by: Andrew Morton --- 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;