Re: [PATCH 1/1] uprobes: Teach handler_chain() to filter out theprobed task

From: Oleg Nesterov
Date: Wed Jan 09 2013 - 13:13:34 EST


On 01/09, Srikar Dronamraju wrote:
>
> * Oleg Nesterov <oleg@xxxxxxxxxx> [2013-01-08 20:00:18]:
>
> > They shouldn't in any case. To remind, we can optimize filter_chain()
> > for example and avoid the potentially costly uc->filter() call. Say,
> > we can detect/remember the fact that at least one consumre has
> > ->filter == NULL.
> >
> > OTOH, UPROBE_HANDLER_REMOVE is not really pre-filtering (although I think
> > it helps to make the things better). It is more like uprobe_unapply_mm()
> > which (perhaps) we need as well. But doing uprobe_unapply_mm() from
> > uc->handler is a) deadlockable and b) not optimal because it has to
> > consult other consumers.
> >
> > Anyway I agree, the folks writing handlers should understand what do they
> > do ;) and this needs some documentation.
>
> If we document explicitly that filter wont be called, then this should
> be okay.

OK.

Can I take this as your ACK?

Oleg.

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