Re: [PATCH v2 1/1] vhost: fix leak of fds and mmaps

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

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