Messages in this thread | | | Date | Thu, 17 Apr 2008 20:05:21 +0400 | From | Oleg Nesterov <> | Subject | Re: fork_idle && pid problems ? |
| |
On 04/17, Pavel Emelyanov wrote: > > Oleg Nesterov wrote: > >> Well, these was some request to make tasks always have pid link > >> point to not NULL (from Matt?) so we'll need this :) > > > > For now I'd suggest the patch below. If contrary to our expectations > > there is any usage of idle_task->pids, we will notice ;) > > > > Oleg. > > > > --- kernel/fork.c~ 2008-03-07 18:11:27.000000000 +0300 > > +++ kernel/fork.c 2008-04-17 19:34:10.000000000 +0400 > > @@ -1420,6 +1420,9 @@ struct task_struct * __cpuinit fork_idle > > if (!IS_ERR(task)) > > init_idle(task, cpu); > > > > + /* COMMENT */ > > + memset(task->pids, 0, sizeof task->pids); > > + > > Hm... Looks ok, but I'd suggest such patch instead: > > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1348,6 +1348,10 @@ static struct task_struct *copy_process(unsigned long clone_flags, > } > attach_pid(p, PIDTYPE_PID, pid); > nr_threads++; > + } else { > + p->pids[PIDTYPE_PID].pid = NULL; > + p->pids[PIDTYPE_SID].pid = NULL; > + p->pids[PIDTYPE_PGID].pid = NULL; > }
This penalizes the "normal" fork()...
> it will cover cases, when we (if ever) call the copy_process from > other place. Oh, well...
We must not use init_struct_pid as an argument for copy_process(), except in fork_idle(). Note that the result of copy_process(init_struct_pid) is not "visible", we can't find it via find_pid() or see it on init_task.tasks.
Not that I have a strong opinion, though. In any case, I think this is harmless. But "not good" anyway.
Oleg.
| |