From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 3/3] eventfd: add internal reference counting to fix notifier race conditions
Date: Tue, 23 Jun 2009 12:55:16 +0930
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Cc: Gregory Haskins <ghaskins@novell.com>, mst@redhat.com,
	kvm@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	avi@redhat.com, paulmck@linux.vnet.ibm.com,
	Ingo Molnar <mingo@elte.hu>
To: Davide Libenzi <davidel@xmailserver.org>
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On Mon, 22 Jun 2009 09:24:20 am Davide Libenzi wrote:
> I actually ended up exposing the eventfd context anyway, since IMO is a
> better option instead of holding references to the eventfd file (that
> makes VFS people uneasy).

lguest is a special case since we don't let them close the fds, except by 
closing /dev/lguest.

Lguest change seems fine, but:

> Index: linux-2.6.mod/drivers/lguest/lg.h
> ===================================================================
> --- linux-2.6.mod.orig/drivers/lguest/lg.h	2009-06-21 15:55:17.000000000
> -0700 +++ linux-2.6.mod/drivers/lguest/lg.h	2009-06-21 15:56:00.000000000
> -0700 @@ -80,9 +80,11 @@ struct lg_cpu {
>  	struct lg_cpu_arch arch;
>  };
>
> +struct eventfd_ctx;
> +
>  struct lg_eventfd {
>  	unsigned long addr;
> -	struct file *event;
> +	struct eventfd_ctx *event;
>  };

The first 'struct eventfd_ctx;' line is not required.

Thanks,
Rusty.