[PATCH 3/4] coredump_wait: don't call complete_vfork_done()

[Oleg Nesterov <oleg@redhat.com>]

Now that CLONE_VFORK is killable, coredump_wait() no longer needs
complete_vfork_done(). zap_threads() should find and kill all tasks
with the same ->mm, this includes our parent if ->vfork_done is set.

mm_release() becomes the only caller, unexport complete_vfork_done().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
 fs/exec.c             |   14 ++------------
 include/linux/sched.h |    1 -
 kernel/fork.c         |    2 +-
 3 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index dccdcec..153dee1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1926,19 +1926,9 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
 		core_waiters = zap_threads(tsk, mm, core_state, exit_code);
 	up_write(&mm->mmap_sem);
 
-	if (unlikely(core_waiters < 0))
-		goto fail;
-
-	/*
-	 * Make sure nobody is waiting for us to release the VM,
-	 * otherwise we can deadlock when we wait on each other
-	 */
-	if (tsk->vfork_done)
-		complete_vfork_done(tsk);
-
-	if (core_waiters)
+	if (core_waiters > 0)
 		wait_for_completion(&core_state->startup);
-fail:
+
 	return core_waiters;
 }
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b646771..11fcafa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2291,7 +2291,6 @@ extern int do_execve(const char *,
 		     const char __user * const __user *,
 		     const char __user * const __user *, struct pt_regs *);
 extern long do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);
-extern void complete_vfork_done(struct task_struct *tsk);
 struct task_struct *fork_idle(int);
 
 extern void set_task_comm(struct task_struct *tsk, char *from);
diff --git a/kernel/fork.c b/kernel/fork.c
index fc2c2f0..57ebebb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -667,7 +667,7 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
 	return mm;
 }
 
-void complete_vfork_done(struct task_struct *tsk)
+static void complete_vfork_done(struct task_struct *tsk)
 {
 	struct completion *vfork;
 
-- 
1.5.5.1