Commit-ID: efb29fbfa50c490dac64a9418ebe553be82df781
Gitweb: http://git.kernel.org/tip/efb29fbfa50c490dac64a9418ebe553be82df781
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 29 Nov 2016 18:51:03 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 8 Dec 2016 14:36:19 +0100
kthread: Don't use to_live_kthread() in kthread_stop()
kthread_stop() had to use to_live_kthread() simply because it was not
possible to access kthread->exited after the exiting task clears
task_struct->vfork_done. Now that to_kthread() is always valid,
wake_up_process() + wait_for_completion() can be done
ununconditionally. It's not an issue anymore if the task has already issued
complete_vfork_done() or died.
The exiting task can get the spurious wakeup after mm_release() but this is
possible without this change too and is fine; do_task_dead() ensures that
this can't make any harm.
As a further enhancement this could be converted to task_work_add() later,
so ->vfork_done can be avoided completely.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Chunming Zhou <David1.Zhou@xxxxxxx>
Cc: Roman Pen <roman.penyaev@xxxxxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20161129175103.GA5336@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/kthread.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 7891a94..4dcbc8b 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -532,13 +532,11 @@ int kthread_stop(struct task_struct *k)
trace_sched_kthread_stop(k);
get_task_struct(k);
- kthread = to_live_kthread(k);
- if (kthread) {
- set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
- __kthread_unpark(k, kthread);
- wake_up_process(k);
- wait_for_completion(&kthread->exited);
- }
+ kthread = to_kthread(k);
+ set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
+ __kthread_unpark(k, kthread);
+ wake_up_process(k);
+ wait_for_completion(&kthread->exited);
ret = k->exit_code;
put_task_struct(k);
--
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