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Re: [PATCH v2 2.6.38-rc8-tip 17/20] 17: uprobes: filter chain
- From: Stephen Wilson <wilsons at start dot ca>
- To: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>
- Cc: Peter Zijlstra <peterz at infradead dot org>, Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Christoph Hellwig <hch at infradead dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Oleg Nesterov <oleg at redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, SystemTap <systemtap at sources dot redhat dot com>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, Andi Kleen <andi at firstfloor dot org>, Andrew Morton <akpm at linux-foundation dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Fri, 18 Mar 2011 18:10:42 -0400
- Subject: Re: [PATCH v2 2.6.38-rc8-tip 17/20] 17: uprobes: filter chain
- References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133722.27435.55663.sendpatchset@localhost6.localdomain6> <20110315194914.GA24972@fibrous.localdomain> <20110318191648.GD31152@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