[RFC PATCH 07/24] fork: expose vfork completion helper

Allow process builders that call copy_process() directly to attach and
wait for the existing vfork completion without duplicating its signal
and task-reference handling.

Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Li Chen <[email protected]>
---
 include/linux/sched/task.h | 3 +++
 kernel/fork.c              | 3 +--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index e0c1ca8c6a188..92b4e3bc31e66 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -14,6 +14,7 @@
 
 struct task_struct;
 struct rusage;
+struct completion;
 union thread_union;
 struct css_set;
 
@@ -99,6 +100,8 @@ extern void exit_itimers(struct task_struct *);
 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
 struct task_struct *copy_process(struct pid *pid, int trace, int node,
 				 struct kernel_clone_args *args);
+int wait_for_vfork_done(struct task_struct *child,
+			struct completion *vfork);
 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
 struct task_struct *fork_idle(int);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
diff --git a/kernel/fork.c b/kernel/fork.c
index f3f378a85be4c..970810a01bbf6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1435,8 +1435,7 @@ static void complete_vfork_done(struct task_struct *tsk)
 	task_unlock(tsk);
 }
 
-static int wait_for_vfork_done(struct task_struct *child,
-				struct completion *vfork)
+int wait_for_vfork_done(struct task_struct *child, struct completion *vfork)
 {
 	unsigned int state = TASK_KILLABLE|TASK_FREEZABLE;
 	int killed;
-- 
2.52.0