From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Subject: Re: [PATCH v2 1/1] vhost: fix leak of fds and mmaps
Date: Mon, 18 Jan 2016 15:58:08 +0800
Message-ID: <20160118075808.GZ19531@yliu-dev.sh.intel.com>
References: <1452032049-94324-1-git-send-email-rlane@bigswitch.com>
 <1453060638-58510-1-git-send-email-rlane@bigswitch.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: dev@dpdk.org
To: Rich Lane <rich.lane@bigswitch.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mga14.intel.com (mga14.intel.com [192.55.52.115])
 by dpdk.org (Postfix) with ESMTP id 9DD9E37AA
 for <dev@dpdk.org>; Mon, 18 Jan 2016 08:56:11 +0100 (CET)
Content-Disposition: inline
In-Reply-To: <1453060638-58510-1-git-send-email-rlane@bigswitch.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Sun, Jan 17, 2016 at 11:57:18AM -0800, Rich Lane wrote:
> The common vhost code only supported a single mmap per device. vhost-user
> worked around this by saving the address/length/fd of each mmap after the end
> of the rte_virtio_memory struct. This only works if the vhost-user code frees
> dev->mem, since the common code is unaware of the extra info. The
> VHOST_USER_RESET_OWNER message is one situation where the common code frees
> dev->mem and leaks the fds and mappings. This happens every time I shut down a
> VM.
> 
> The new code calls back into the implementation (vhost-user or vhost-cuse) to
> clean up these resources.
> 
> The vhost-cuse changes are only compile tested.
> 
> Signed-off-by: Rich Lane <rlane@bigswitch.com>
> ---
> v1->v2:
> - Call into vhost-user/vhost-cuse to free mmaps.
> 
>  lib/librte_vhost/vhost-net.h                  |  6 ++++++
>  lib/librte_vhost/vhost_cuse/virtio-net-cdev.c | 12 ++++++++++++
>  lib/librte_vhost/vhost_user/vhost-net-user.c  |  1 -
>  lib/librte_vhost/vhost_user/virtio-net-user.c | 25 ++++++++++---------------
>  lib/librte_vhost/vhost_user/virtio-net-user.h |  1 -
>  lib/librte_vhost/virtio-net.c                 |  8 +-------
>  6 files changed, 29 insertions(+), 24 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost-net.h b/lib/librte_vhost/vhost-net.h
> index c69b60b..e8d7477 100644
> --- a/lib/librte_vhost/vhost-net.h
> +++ b/lib/librte_vhost/vhost-net.h
> @@ -115,4 +115,10 @@ struct vhost_net_device_ops {
>  
>  
>  struct vhost_net_device_ops const *get_virtio_net_callbacks(void);
> +
> +/*
> + * Implementation-specific cleanup. Defined by vhost-cuse and vhost-user.
> + */
> +void vhost_impl_cleanup(struct virtio_net *dev);

TBH, I am not quite like "_impl_"; maybe "_backend_" is better?

OTOH, what I thought of has slight difference than yours: not
necessary to export a function, but instead, call the vhost
backend specific unmap function inside the backend itself. Say,
call vhost_user_unmap() on RESET_OWNER and connection close.
What do you think of that?

	--yliu