[PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.

[Srikar Dronamraju]

* Stephen Wilson <wilsons@start.ca> [2011-03-14 14:09:14]:

> On Mon, Mar 14, 2011 at 07:05:22PM +0530, Srikar Dronamraju wrote:
> >  static int install_uprobe(struct mm_struct *mm, struct uprobe *uprobe)
> >  {
> > -	int ret = 0;
> > +	struct task_struct *tsk;
> > +	int ret = -EINVAL;
> >  
> > -	/*TODO: install breakpoint */
> > -	if (!ret)
> > +	get_task_struct(mm->owner);
> > +	tsk = mm->owner;
> > +	if (!tsk)
> > +		return ret;
> 
> I think you need to check that tsk != NULL before calling
> get_task_struct()...
> 

Guess checking for tsk != NULL would only help if and only if we are doing
within rcu.  i.e we have to change to something like this

	rcu_read_lock()
	if (mm->owner) {
		get_task_struct(mm->owner)
		tsk = mm->owner;
	}
	rcu_read_unlock()
	if (!tsk)
		return ret;

Agree?