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Date: Tue, 20 Jun 2006 18:46:17 -0700
From: Andrew Morton <akpm@osdl.org>
To: Matt Helsley <matthltc@us.ibm.com>
Cc: pwil3058@bigpond.net.au, nagar@watson.ibm.com, sekharan@us.ibm.com,
       jtk@us.ibm.com, balbir@in.ibm.com, jes@sgi.com,
       linux-kernel@vger.kernel.org, stern@rowland.harvard.edu,
       lse-tech@lists.sourceforge.net
Subject: Re: [Lse-tech] [PATCH 09/11] Task watchers: Add support for
 per-task watchers
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On Tue, 20 Jun 2006 18:20:48 -0700
Matt Helsley <matthltc@us.ibm.com> wrote:

> > > > > +static inline int notify_per_task_watchers(unsigned int val,
> > > > > +					   struct task_struct *task)
> > > > > +{
> > > > > +	if (get_watch_event(val) != WATCH_TASK_INIT)
> > > > > +		return raw_notifier_call_chain(&task->notify, val, task);
> > > > > +	RAW_INIT_NOTIFIER_HEAD(&task->notify);
> > > > > +	if (task->real_parent)
> > > > > +		return raw_notifier_call_chain(&task->real_parent->notify,
> > > > > +		   			       val, task);
> > > > > +}
> > > > 
> > > > It's possible for this task to exit without returning a result.
> > > 
> > > Assuming you meant s/task/function/:
> > > 
> > > 	In the common case this will return a result because most tasks have a
> > > real parent. The only exception should be the init task. However, the
> > > init task does not "fork" from another task so this function will never
> > > get called with WATCH_TASK_INIT and the init task.
> > > 
> > > 	This means that if one wants to use per-task watchers to associate data
> > > and a function call with *every* task, special care will need to be
> > > taken to register with the init task.
> > 
> > no......
> 
> 	I've been looking through the source and, from what I can see, the end
> of the function is not reachable. I think I need to add:
> 
> notify_watchers(WATCH_TASK_INIT, &init_task);
> 
> to make this into an applicable warning.

If the end of the function isn't reachable then the
`if (task->real_parent)' can simply be removed.