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In-Reply-To: <201002131133.43028.arnd@arndb.de>
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Date: Mon, 15 Feb 2010 15:48:40 -0800
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From: Ed Swierk <eswierk@aristanetworks.com>
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Subject: [Qemu-devel] Re: [PATCH 1/2] macvtap: rework object lifetime rules
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To: Arnd Bergmann <arnd@arndb.de>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org, qemu-devel@nongnu.org, linux-kernel@vger.kernel.org, Patrick McHardy <kaber@trash.net>, Sridhar Samudrala <sri@us.ibm.com>

On Sat, Feb 13, 2010 at 2:33 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> The original macvtap code has a number of problems
> resulting from the use of RCU for protecting the
> access to struct macvtap_queue from open files.
>
> This includes
> - need for GFP_ATOMIC allocations for skbs
> - potential deadlocks when copy_*_user sleeps
> - inability to work with vhost-net
>
> Changing the lifetime of macvtap_queue to always
> depend on the open file solves all these. The
> RCU reference simply moves one step down to
> the reference on the macvlan_dev, which we
> only need for nonblocking operations.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

This works for me.

Acked-by: Ed Swierk <eswierk@aristanetworks.com>