On 04/08, Eric W. Biederman wrote:
>
> Agreed. That is ugly.
Yes, I agree also.
>
> -#define thread_group_leader(p) (p->pid == p->tgid)
> +#define thread_group_leader(p) (p == p->group_leader)
>
> ...
>
> - leader->group_leader = leader;
> + leader->group_leader = current;
I thought about similar change too, but I am unsure about
release_task(old_leader)->proc_flush_task() path (because
I don't understand this code).
This change can confuse next_tid(), but this is minor.
I don't see other problems.
However, I think we can do something better instead of
attach_pid(current)/detach_pid(leader):
void exec_pid(task_t *old, task_t * new, enum pid_type type)
{
new->pids[type].pid = old->pids[type].pid;
hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
old->pids[type].pid = NULL;
}
So de_thread() can do
exec_pid(leader, current, PIDTYPE_PGID);
exec_pid(leader, current, PIDTYPE_SID);
This allows us to iterate over pgrp/session lockless without
seeing the same task twice, btw. But may be it is just unneeded
complication.
> This requires changing the leaders parents
>
> current->parent = current->real_parent = leader->real_parent;
> - leader->parent = leader->real_parent = child_reaper;
> + leader->parent = leader->real_parent = current;
> current->group_leader = current;
I don't understand why do we need this change.
Actually, I think leader doesn't need reparenting at all.
ptrace_unlink(leader) already restored leader->parent = ->real_parent
and ->sibling. So I think we can do (for review only, should go in a
separate patch) this:
--- MM/fs/exec.c~ 2006-04-08 02:19:15.000000000 +0400
+++ MM/fs/exec.c 2006-04-08 18:50:35.000000000 +0400
@@ -704,7 +704,6 @@ static int de_thread(struct task_struct
ptrace_unlink(current);
ptrace_unlink(leader);
remove_parent(current);
- remove_parent(leader);
/* Become a process group leader with the old leader's pid.
@@ -718,13 +717,11 @@ static int de_thread(struct task_struct
attach_pid(current, PIDTYPE_SID, current->signal->session);
list_replace_rcu(&leader->tasks, ¤t->tasks);
- current->parent = current->real_parent = leader->real_parent;
- leader->parent = leader->real_parent = child_reaper;
+ current->parent = current->real_parent = leader->parent;
current->group_leader = current;
leader->group_leader = leader;
add_parent(current);
- add_parent(leader);
if (ptrace) {
current->ptrace = ptrace;
__ptrace_link(current, parent);
Oleg.
-
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