Subject: + wait-use-exit_trace-only-if-thread_group_leaderzombie.patch added to -mm tree
To: oleg@xxxxxxxxxx,jan.kratochvil@xxxxxxxxxx,lpoetter@xxxxxxxxxx,mschmidt@xxxxxxxxxx,roland@xxxxxxxxxxxxx,tj@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 21 Feb 2014 13:39:19 -0800
The patch titled
Subject: wait: use EXIT_TRACE only if thread_group_leader(zombie)
has been added to the -mm tree. Its filename is
wait-use-exit_trace-only-if-thread_group_leaderzombie.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/wait-use-exit_trace-only-if-thread_group_leaderzombie.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/wait-use-exit_trace-only-if-thread_group_leaderzombie.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: wait: use EXIT_TRACE only if thread_group_leader(zombie)
wait_task_zombie() always uses EXIT_TRACE/ptrace_unlink() if
ptrace_reparented(). This is suboptimal and a bit confusing: we do not
need do_notify_parent(p) if !thread_group_leader(p) and in this case we
also do not need ptrace_unlink(), we can rely on ptrace_release_task().
Change wait_task_zombie() to check thread_group_leader() along with
ptrace_reparented() and simplify the final p->exit_state transition.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Tested-by: Michal Schmidt <mschmidt@xxxxxxxxxx>
Cc: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Lennart Poettering <lpoetter@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff -puN kernel/exit.c~wait-use-exit_trace-only-if-thread_group_leaderzombie kernel/exit.c
--- a/kernel/exit.c~wait-use-exit_trace-only-if-thread_group_leaderzombie
+++ a/kernel/exit.c
@@ -1042,7 +1042,7 @@ static int wait_task_zombie(struct wait_
/*
* Move the task's state to DEAD/TRACE, only one thread can do this.
*/
- state = traced ? EXIT_TRACE : EXIT_DEAD;
+ state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD;
if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
return 0;
/*
@@ -1142,18 +1142,15 @@ static int wait_task_zombie(struct wait_
if (!retval)
retval = pid;
- if (traced) {
+ if (state == EXIT_TRACE) {
write_lock_irq(&tasklist_lock);
/* We dropped tasklist, ptracer could die and untrace */
ptrace_unlink(p);
- /*
- * If this is not a sub-thread, notify the parent.
- * If parent wants a zombie, don't release it now.
- */
- state = EXIT_DEAD;
- if (thread_group_leader(p) &&
- !do_notify_parent(p, p->exit_signal))
- state = EXIT_ZOMBIE;
+
+ /* If parent wants a zombie, don't release it now */
+ state = EXIT_ZOMBIE;
+ if (do_notify_parent(p, p->exit_signal))
+ state = EXIT_DEAD;
p->exit_state = state;
write_unlock_irq(&tasklist_lock);
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
kthread-ensure-locality-of-task_struct-allocations.patch
wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch
wait-introduce-exit_trace-to-avoid-the-racy-exit_dead-exit_zombie-transition.patch
wait-use-exit_trace-only-if-thread_group_leaderzombie.patch
wait-completely-ignore-the-exit_dead-tasks.patch
wait-swap-exit_zombie-and-exit_dead-to-hide-exit_trace-from-user-space.patch
linux-next.patch
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