fork: Provide weak arch_release_[task_struct|thread_info] functions

These functions allow us to move most of the duplicated thread_info
allocators to the core code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120505150141.366461660@linutronix.de

kernel/fork.c

@@ -112,14 +112,26 @@ int nr_processes(void)
 }
 
 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
-# define alloc_task_struct_node(node)		\
-		kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
-# define free_task_struct(tsk)			\
-		kmem_cache_free(task_struct_cachep, (tsk))
 static struct kmem_cache *task_struct_cachep;
+
+static inline struct task_struct *alloc_task_struct_node(int node)
+{
+	return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
+}
+
+void __weak arch_release_task_struct(struct task_struct *tsk) { }
+
+static inline void free_task_struct(struct task_struct *tsk)
+{
+	arch_release_task_struct(tsk);
+	kmem_cache_free(task_struct_cachep, tsk);
+}
 #endif
 
 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
+
+void __weak arch_release_thread_info(struct thread_info *ti) { }
+
 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
 						  int node)
 {
@@ -131,6 +143,7 @@ static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
 
 static inline void free_thread_info(struct thread_info *ti)
 {
+	arch_release_thread_info(ti);
 	free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
 }
 #endif