[CRIU] [PATCH 28/32] tools: cpt2 -- Add writing of pstree entries

[Cyrill Gorcunov]

On Mon, Apr 01, 2013 at 02:29:23PM +0400, Pavel Emelyanov wrote:
> > +	list_for_each_entry(task, &task_list, list) {
> > +		ret = write_pstree_item(pstree_fd, task, &e,
> > +					threads, max_threads);
> > +		if (ret)
> > +			goto out;
> > +		list_for_each_entry(child, &task->children, list) {
> > +			ret = write_pstree_item(pstree_fd, child,
> > +						&e, threads, max_threads);
> > +			if (ret)
> > +				goto out;
> > +		}
> > +	}
> 
> Does task_list contain all tasks? In that case we'll write some tasks twice.
> Does it contain only even-levels of tasks? O_O

At first task_list gathers all tasks from cpt file, then we walk over
the tree and connect tasks to respective parents, to have process tree
at the end of ptocess.

read_tasks
	...
	hash_add(pids_hash, &task->hash, task->ti.cpt_pid);
	list_add_tail(&task->list, &task_list);

	list_for_each_entry_safe(task, tmp, &task_list, list)
		collect_task(task);

static void collect_task(struct task_struct *task)
{
	struct task_struct *t;

	/*
	 * We don't care if there is some of PIDs
	 * are screwed, the crtools will refuse to
	 * restore if someone pass us coeeupted data.
	 *
	 * Thus we only collect threads and children.
	 */
	t = task_lookup_pid(task->ti.cpt_ppid);
	if (t) {
		task->parent = t;
		list_move(&task->list, &t->children);
		return;
	}

	t = task_lookup_pid(task->ti.cpt_rppid);
	if (t) {
		list_move(&task->list, &t->threads);
		t->n_threads++;

		if (max_threads < t->n_threads)
			max_threads = t->n_threads;
		return;
	}
}