pidns: Consolidate initialzation of special init task state

Instead of setting child_reaper and SIGNAL_UNKILLABLE one way
for the system init process, and another way for pid namespace
init processes test pid->nr == 1 and use the same code for both.

For the global init this results in SIGNAL_UNKILLABLE being set
much earlier in the initialization process.

This is a small cleanup and it paves the way for allowing unshare and
enter of the pid namespace as that path like our global init also will
not set CLONE_NEWPID.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 3 insertions, 4 deletions

diff --git a/init/main.c b/init/main.c
index 9cf77ab138a6..317750a18f74 100644
--- a/init/main.c
+++ b/init/main.c
@@ -810,7 +810,6 @@ static int __ref kernel_init(void *unused)
         system_state = SYSTEM_RUNNING;
         numa_default_policy();
 
-        current->signal->flags |= SIGNAL_UNKILLABLE;
         flush_delayed_fput();
 
         if (ramdisk_execute_command) {
diff --git a/kernel/fork.c b/kernel/fork.c
index 666dc8b06606..0f2bbce311fc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1039,8 +1039,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         atomic_set(&sig->live, 1);
         atomic_set(&sig->sigcnt, 1);
         init_waitqueue_head(&sig->wait_chldexit);
-        if (clone_flags & CLONE_NEWPID)
-                sig->flags |= SIGNAL_UNKILLABLE;
         sig->curr_target = tsk;
         init_sigpending(&sig->shared_pending);
         INIT_LIST_HEAD(&sig->posix_timers);
@@ -1441,8 +1439,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
 
                 if (thread_group_leader(p)) {
-                        if (is_child_reaper(pid))
+                        if (is_child_reaper(pid)) {
                                 ns_of_pid(pid)->child_reaper = p;
+                                p->signal->flags |= SIGNAL_UNKILLABLE;
+                        }
 
                         p->signal->leader_pid = pid;
                         p->signal->tty = tty_kref_get(current->signal->tty);