[RFC PATCH 08/18] kthread: Allow to get struct kthread_iterant from task_struct

[Petr Mladek]

It is easy to make a mistake when one implements sleeping between kthread
iterations. We will want to do it a more uniform way. For this we will
want to set some flags in struct kthread_iterant from the current
task (kthread). This patch adds the basic infrastructure to make
it possible.

Signed-off-by: Petr Mladek <pmladek at suse.cz>
---
 kernel/kthread.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index e34f67cb8ecf..41fb6a43a1f1 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -44,6 +44,7 @@ struct kthread {
 	void *data;
 	struct completion parked;
 	struct completion exited;
+	struct kthread_iterant *kti;
 };
 
 enum KTHREAD_BITS {
@@ -69,6 +70,11 @@ static struct kthread *to_live_kthread(struct task_struct *k)
 	return NULL;
 }
 
+static struct kthread_iterant *to_kthread_iterant(struct task_struct *k)
+{
+	return __to_kthread(k->vfork_done)->kti;
+}
+
 /**
  * kthread_stop_current - make the current kthread to terminate a safe way
  *
@@ -199,6 +205,7 @@ static int kthread(void *_create)
 	self.data = data;
 	init_completion(&self.exited);
 	init_completion(&self.parked);
+	self.kti = NULL;
 	current->vfork_done = &self.exited;
 
 	/* If user was SIGKILLed, I release the structure. */
@@ -421,9 +428,12 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
  */
 static int kthread_iterant_fn(void *kti_ptr)
 {
+	struct kthread *kt = to_kthread(current);
 	struct kthread_iterant *kti = kti_ptr;
 	void *data = kti->data;
 
+	kt->kti = kti;
+
 	set_freezable();
 
 	if (kti->init)
-- 
1.8.5.6