kthread: implement kthread_data()

Implement kthread_data() which takes @task pointing to a kthread and
returns @data specified when creating the kthread.  The caller is
responsible for ensuring the validity of @task when calling this
function.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index f93cb69..685ea65 100644 (file)
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -30,6 +30,7 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 int kthread_stop(struct task_struct *k);
 int kthread_should_stop(void);
+void *kthread_data(struct task_struct *k);
 
 int kthreadd(void *unused);
 extern struct task_struct *kthreadd_task;

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 8b63c7f..2dc3786 100644 (file)
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -37,6 +37,7 @@ struct kthread_create_info
 
 struct kthread {
        int should_stop;
+       void *data;
        struct completion exited;
 };
 
@@ -56,6 +57,19 @@ int kthread_should_stop(void)
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
+/**
+ * kthread_data - return data value specified on kthread creation
+ * @task: kthread task in question
+ *
+ * Return the data value specified when kthread @task was created.
+ * The caller is responsible for ensuring the validity of @task when
+ * calling this function.
+ */
+void *kthread_data(struct task_struct *task)
+{
+       return to_kthread(task)->data;
+}
+
 static int kthread(void *_create)
 {
        /* Copy data: it's on kthread's stack */
@@ -66,6 +80,7 @@ static int kthread(void *_create)
        int ret;
 
        self.should_stop = 0;
+       self.data = data;
        init_completion(&self.exited);
        current->vfork_done = &self.exited;