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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 <oleg@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2023-09-09 23:49:51 +02:00 committed by Andrew Morton
parent 13b7bc60b5
commit ed5378a387
1 changed files with 2 additions and 3 deletions
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5
kernel/taskstats.c
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@ -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;