With or without this patch, multi-threaded init's are not fully supported, but
do_exit() is completely wrong. This becomes a real problem when we support pid
namespaces.
1. do_exit() panics when the main thread of /sbin/init exits. It should not
until the whole thread group exits. Move the code below, under the
"if (group_dead)" check.
Note: this means that forget_original_parent() can use an already dead
child_reaper()'s task_struct. This is OK for /sbin/init because
- do_wait() from alive sub-thread still can reap a zombie, we iterate
over all sub-thread's ->children lists
- do_notify_parent() will wakeup some alive sub-thread because it sends
the group-wide signal
However, we should remove choose_new_parent()->BUG_ON(reaper->exit_state)
for this.
2. We are playing games with ->nsproxy->pid_ns. This code is bogus today, and
it has to be changed anyway when we really support pid namespaces, just
remove it.
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
--- t/kernel/exit.c~ 2007-08-03 00:10:28.000000000 +0400
+++ t/kernel/exit.c 2007-08-03 01:12:18.000000000 +0400
@@ -604,11 +604,6 @@ static void exit_mm(struct task_struct *
static inline void
choose_new_parent(struct task_struct *p, struct task_struct *reaper)
{
- /*
- * Make sure we're not reparenting to ourselves and that
- * the parent is not a zombie.
- */
- BUG_ON(p == reaper || reaper->exit_state);
p->real_parent = reaper;
}
@@ -895,6 +890,14 @@ static void check_stack_usage(void)
static inline void check_stack_usage(void) {}
#endif
+static inline void exit_child_reaper(struct task_struct *tsk)
+{
+ if (likely(tsk->group_leader != child_reaper(tsk)))
+ return;
+
+ panic("Attempted to kill init!");
+}
+
fastcall NORET_TYPE void do_exit(long code)
{
struct task_struct *tsk = current;
@@ -908,13 +911,6 @@ fastcall NORET_TYPE void do_exit(long co
panic("Aiee, killing interrupt handler!");
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!");
- if (unlikely(tsk == child_reaper(tsk))) {
- if (tsk->nsproxy->pid_ns != &init_pid_ns)
- tsk->nsproxy->pid_ns->child_reaper =
init_pid_ns.child_reaper;
- else
- panic("Attempted to kill init!");
- }
-
if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
current->ptrace_message = code;
@@ -964,6 +960,7 @@ fastcall NORET_TYPE void do_exit(long co
}
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
+ exit_child_reaper(tsk);
hrtimer_cancel(&tsk->signal->real_timer);
exit_itimers(tsk->signal);
}
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