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Date: Thu, 24 Nov 2011 12:33:03 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>,
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        Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>,
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        Steven Rostedt <rostedt@goodmis.org>,
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        Anton Arapov <anton@redhat.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Jim Keniston <jkenisto@linux.vnet.ibm.com>, tulasidhard@gmail.com
Subject: Re: Fwd: uprobes: register/unregister probes.
Message-ID: <20111124070303.GB28065@linux.vnet.ibm.com>
Reply-To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
References: <hYuXv-26J-3@gated-at.bofh.it>
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> On Fri, 2011-11-18 at 16:37 +0530, Srikar Dronamraju wrote:
> > +int register_uprobe(struct inode *inode, loff_t offset,
> > +                               struct uprobe_consumer *consumer)
> > +{
> > +       struct uprobe *uprobe;
> > +       int ret = -EINVAL;
> > +
> > +       if (!consumer || consumer->next)
> > +               return ret;
> > +
> > +       inode = igrab(inode);
> 
> So why are you dealing with !consumer but not with !inode? and why
> does
> it make sense to allow !consumer at all?
> 


I am not sure if I got your comment correctly.

I do check for inode just after the igrab.

I am actually not dealing with !consumer.
If the consumer is NULL, then we dont have any handler to run so why
would we want to register such a probe?

Also if consumer->next is Non-NULL, that means that this consumer was
already used.  Reusing the consumer, can result in consumers list getting
broken into two.

If you meant something else please clarify.

-- 
Thanks and Regards
Srikar