Re: [PATCH] vhost: fix driver unregister for client mode

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

On Wed, Jul 20, 2016 at 11:32:43AM +0300, Ilya Maximets wrote:
> Currently while calling of 'rte_vhost_driver_unregister()' connection
> to QEMU will not be closed. This leads to inability to register driver
> again and reconnect to same virtual machine.
> 
> This scenario is reproducible with OVS. While executing of the following
> command vhost port will be re-created (will be executed
> 'rte_vhost_driver_register()' followed by 'rte_vhost_driver_unregister()')
> network will be broken and QEMU possibly will crash:
> 
> 	ovs-vsctl set Interface vhost1 ofport_request=15
> 
> Fix this by closing all established connections on driver unregister and
> removing of pending connections from reconnection list.
> 
> Fixes: 64ab701c3d1e ("vhost: add vhost-user client mode")
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>

Again, thanks for the fix.

> ---
> 
> Patch prepared for master branch because dpdk-next-virtio doesn't contain
> commit acbff5c67ea7 ("vhost: fix crash when exceeding file descriptors").
> Porting to dpdk-next-virtio/master is trivial and may be performed on
> demand.

Yeah, my bad, I haven't updated it after rc2, since Thomas no longer
pull request from it.  Anyway, you just remind me that I should have
done that.

>  /**
>   * Unregister the specified vhost socket
>   */
> @@ -672,20 +700,34 @@ rte_vhost_driver_unregister(const char *path)
>  {
>  	int i;
>  	int count;
> +	struct vhost_user_connection *conn;
>  
>  	pthread_mutex_lock(&vhost_user.mutex);
>  
>  	for (i = 0; i < vhost_user.vsocket_cnt; i++) {
> -		if (!strcmp(vhost_user.vsockets[i]->path, path)) {
> -			if (vhost_user.vsockets[i]->is_server) {
> -				fdset_del(&vhost_user.fdset,
> -					vhost_user.vsockets[i]->listenfd);
> -				close(vhost_user.vsockets[i]->listenfd);
> +		struct vhost_user_socket *vsocket = vhost_user.vsockets[i];
> +
> +		if (!strcmp(vsocket->path, path)) {
> +			if (vsocket->is_server) {
> +				(void) fdset_del(&vhost_user.fdset,
> +				                 vsocket->listenfd);

I would think the (void) cast is not neceessary here.

> +				close(vsocket->listenfd);
>  				unlink(path);
> +			} else if (vsocket->reconnect) {
> +				vhost_user_remove_reconnect(vsocket);
> +			}
> +
> +			conn = fdset_del(&vhost_user.fdset, vsocket->connfd);
> +			if (conn) {
> +				RTE_LOG(INFO, VHOST_CONFIG, "free connfd = %d"
> +				    "for device '%s'\n", vsocket->connfd, path);

We should try not to break a log message into several lines, which
hurts "git grep".  Here, it could be:

				RTE_LOG(INFO, VHOST_CONFIG,
					"free connfd = %d for device '%s'\n",
					vsocket->connfd, path);

Besides the two minor nits,

Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

	--yliu