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authorOleg Nesterov <oleg@redhat.com>2016-11-29 18:51:03 +0100
committerThomas Gleixner <tglx@linutronix.de>2016-12-08 14:36:19 +0100
commitefb29fbfa50c490dac64a9418ebe553be82df781 (patch)
tree8b67af676011ff5aa7f4f3b008351952ece99fbb /kernel/kthread.c
parenteff9662547f358239b98dfc4a8e6905b494e14d6 (diff)
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@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Chunming Zhou <David1.Zhou@amd.com> Cc: Roman Pen <roman.penyaev@profitbricks.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Tejun Heo <tj@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20161129175103.GA5336@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/kthread.c')
-rw-r--r--kernel/kthread.c12
1 files changed, 5 insertions, 7 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 7891a940007d..4dcbc8b5d6b6 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);