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Date: Fri, 7 Oct 2011 19:03:47 +0200
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v5 3.1.0-rc4-tip 3/26]   Uprobes: register/unregister
	probes.
Message-ID: <20111007170347.GB32319@redhat.com>
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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>, Jonathan Corbet <corbet@lwn.net>, Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <andi@firstfloor.org>, LKML <linux-kernel@vger.kernel.org>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Andrew Morton <akpm@linux-foundation.org>

On 10/06, Srikar Dronamraju wrote:
>
> * Oleg Nesterov <oleg@redhat.com> [2011-10-05 20:50:08]:
>
> yes we might be doing an unnecessary __register_uprobe() but because it
> raced with unregister_uprobe() and got the lock, we would avoid doing a
> __unregister_uprobe().
>
> However I am okay to move the lock before del_consumer().

To me this looks a bit "safer" even if currently __register is idempotent.

But,

> Please let me
> know how you prefer this.

No, no, Srikar. Please do what you prefer. You are the author.

And btw I forgot to mention that initially I wrongly thought this is buggy.

Oleg.

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