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Date: Fri, 18 Mar 2011 18:10:42 -0400
From: Stephen Wilson <wilsons@start.ca>
Subject: Re: [PATCH v2 2.6.38-rc8-tip 17/20] 17: uprobes: filter chain
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To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Christoph Hellwig <hch@infradead.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>, SystemTap <systemtap@sources.redhat.com>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Andi Kleen <andi@firstfloor.org>, Andrew Morton <akpm@linux-foundation.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>


On Sat, Mar 19, 2011 at 12:46:48AM +0530, Srikar Dronamraju wrote:
> > > +	for (consumer = uprobe->consumers; consumer;
> > > +					consumer = consumer->next) {
> > > +		if (!consumer->filter || consumer->filter(consumer, t)) {
> > 
> > The implementation does not seem to match the changelog description.
> > Should this not be:
> > 
> >                 if (consumer->filter && consumer->filter(consumer, t))
> > 
> >   ?
> 
> filter is optional; if filter is present, then it means that the
> tracer is interested in a specific set of processes that maps this
> inode. If there is no filter; it means that it is interested in all
> processes that map this filter. 

Ah OK.  That does make sense then.  Thanks!


> filter_chain() should return true if any consumer is interested in
> tracing this task.  if there is a consumer who hasnt defined a filter
> then we dont need to loop thro remaining consumers.
> 
> Hence 
> 
> if (!consumer->filter || consumer->filter(consumer, t)) {
>  
> seems better suited to me.

-- 
steve

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