Re: [Lse-tech] [PATCH 09/11] Task watchers: Add support for per-task watchers

[Andrew M. <ak...@os...>]

Matt Helsley <mat...@us...> 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......

It's possible for this function to fall off the end without returning
anything.  The compiler should have spat a warning.