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

[Pavel Emelyanov]

On 04/01/2013 02:54 PM, Cyrill Gorcunov wrote:
> 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.

So task_list contains all the tasks. Why do we write each entry _and_ _it's_
_children_ on every loop? Won't children be in image twice after this?

> 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;
> 	}
> }
> .
>