RDMA/restrack: Add an API to attach a task to a resource

Add rdma_restrack_attach_task() which is able to attach a task other then
"current" to a resource.
Signed-off-by: NMark Zhang <markz@mellanox.com>
Reviewed-by: NMajd Dibbiny <majd@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/restrack.c

@@ -194,6 +194,20 @@ void rdma_restrack_set_task(struct rdma_restrack_entry *res,
 }
 EXPORT_SYMBOL(rdma_restrack_set_task);
 
+/**
+ * rdma_restrack_attach_task() - attach the task onto this resource
+ * @res:  resource entry
+ * @task: the task to attach, the current task will be used if it is NULL.
+ */
+void rdma_restrack_attach_task(struct rdma_restrack_entry *res,
+			       struct task_struct *task)
+{
+	if (res->task)
+		put_task_struct(res->task);
+	get_task_struct(task);
+	res->task = task;
+}
+
 static void rdma_restrack_add(struct rdma_restrack_entry *res)
 {
 	struct ib_device *dev = res_to_dev(res);

drivers/infiniband/core/restrack.h

@@ -25,4 +25,6 @@ struct rdma_restrack_root {
 
 int rdma_restrack_init(struct ib_device *dev);
 void rdma_restrack_clean(struct ib_device *dev);
+void rdma_restrack_attach_task(struct rdma_restrack_entry *res,
+			       struct task_struct *task);
 #endif /* _RDMA_CORE_RESTRACK_H_ */