[PATCH 2/5] cgroup: remove redundant get/put of task struct

[Mandeep Singh Baines]

Tejun Heo (tj at kernel.org) wrote:
> Hello,
> 
> On Tue, Dec 20, 2011 at 03:14:30PM -0800, Mandeep Singh Baines wrote:
> > @@ -2287,14 +2280,12 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
> >  			cgroup_unlock();
> >  			return -EACCES;
> >  		}
> > -		get_task_struct(tsk);
> >  		rcu_read_unlock();
> 
> This is before threadgroup is locked.  What guarantees @tsk doesn't go
> away once rcu is unlocked?
> 

Nothing. D'oh. I'll remove the changes to attach_task_by_id and leave
the others.

> Thanks.
> 
> -- 
> tejun