Re: [RFC] Design + prototype: Multiple handler sets per probe address

[Ananth N Mavinakayanahalli <amavin at redhat dot com>]

William Cohen wrote:
> Ananth N Mavinakayanahalli wrote:
>
> > William Cohen wrote:
>
> ...
>
> > > I appologize for the verbose output. I have also attached output of 
> > > the test results. There are some warning about allocating sleeping 
> > > function.
> >
> >
> >
> > The warning appears only in one of the eight runs. Will investigate
> > this. A GFP_KERNEL/GFP_ATOMIC issue, probably - but if so, why only in
> > one of the eight runs? Beats me!
>
>
> I suspect that is the first time that kprobes needs to really allocate 
> memory. The remaining kprobes can uses that access from iteration 1 of 
> the loop.

The third unregister_kprobe() call will kfree() the aggr_kp in each
iteration.

> ...
>
> > > It seems like it would be useful to have unregister_kprobe() return 
> > > whether the operation was successful or not. Be able to catch cases 
> > > were code attempts to remove a probe twice.
> >
> >
> >
> > Changing the existing interface :-) But I suppose users who don't care
> > about the return code may as well ignore it.
>
>
> It was a thought. Trying to make the code be better able to determine 
> when something has gone wrong.

In fact, Suparna suggested an alternate design approach to the multiple
handlers issue. I will try and work on that design too - Suparna's
method has the advantage that we may not have to modify the arch
specific kprobe code at all.

Thanks,
Ananth