[PATCH v2 2/5] Revert "kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function"

From: Oleg Nesterov
Date: Tue Nov 29 2016 - 12:51:33 EST


This reverts commit 23196f2e5f5d810578a772785807dcdc2b9fdce9.

After the previous change struct kthread can't go away, no need to pin
the stack.

TODO: kill to_live_kthread().

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/kthread.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 9d64b65..7891a94 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -88,7 +88,7 @@ void free_kthread_struct(struct task_struct *k)
static struct kthread *to_live_kthread(struct task_struct *k)
{
struct completion *vfork = ACCESS_ONCE(k->vfork_done);
- if (likely(vfork) && try_get_task_stack(k))
+ if (likely(vfork))
return __to_kthread(vfork);
return NULL;
}
@@ -473,10 +473,8 @@ void kthread_unpark(struct task_struct *k)
{
struct kthread *kthread = to_live_kthread(k);

- if (kthread) {
+ if (kthread)
__kthread_unpark(k, kthread);
- put_task_stack(k);
- }
}
EXPORT_SYMBOL_GPL(kthread_unpark);

@@ -505,7 +503,6 @@ int kthread_park(struct task_struct *k)
wait_for_completion(&kthread->parked);
}
}
- put_task_stack(k);
ret = 0;
}
return ret;
@@ -541,7 +538,6 @@ int kthread_stop(struct task_struct *k)
__kthread_unpark(k, kthread);
wake_up_process(k);
wait_for_completion(&kthread->exited);
- put_task_stack(k);
}
ret = k->exit_code;
put_task_struct(k);
--
2.5.0