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

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

* Thomas Gleixner <tglx@linutronix.de> [2011-03-15 15:41:20]:

> On Mon, 14 Mar 2011, 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);
> 
> Increment task ref before checking for NULL ?

In response to earlier comments/suggestions from Stephen Wilson, we
resolved to handle it this way 


static uprobes_get_mm_owner() {
	struct task_struct *tsk; 

	rcu_read_lock()
	tsk = rcu_dereference(mm->owner);
	if (tsk)
		get_task_struct(tsk);	
	rcu_read_unlock();
	return tsk;
}

Both install_uprobe and remove_uprobe will end up calling uprobes_get_mm_owner().


-- 
Thanks and Regards
Srikar

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