The patch titled
Subject: taskstats: fill_stats_for_tgid: use for_each_thread()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
taskstats-fill_stats_for_tgid-use-for_each_thread.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/taskstats-fill_stats_for_tgid-use-for_each_thread.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: taskstats: fill_stats_for_tgid: use for_each_thread()
Date: Sat, 9 Sep 2023 23:49:51 +0200
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@xxxxxxxxxx
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/taskstats.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/kernel/taskstats.c~taskstats-fill_stats_for_tgid-use-for_each_thread
+++ a/kernel/taskstats.c
@@ -233,9 +233,8 @@ static int fill_stats_for_tgid(pid_t tgi
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 tgi
stats->nvcsw += tsk->nvcsw;
stats->nivcsw += tsk->nivcsw;
- } while_each_thread(first, tsk);
+ }
unlock_task_sighand(first, &flags);
rc = 0;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
introduce-__next_thread-fix-next_tid-vs-exec-race.patch
change-next_thread-to-use-__next_thread-group_leader.patch
change-thread_group_empty-to-use-task_struct-thread_node.patch
kill-task_struct-thread_group.patch
__kill_pgrp_info-simplify-the-calculation-of-return-value.patch
getrusage-add-the-signal_struct-sig-local-variable.patch
getrusage-use-__for_each_thread.patch
taskstats-fill_stats_for_tgid-use-for_each_thread.patch
