Re: [dpdk-dev] [PATCH] vhost: fix double free on shutdown

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Tomasz Kulasek
> Sent: Saturday, February 10, 2018 1:15 AM
> To: yliu@fridaylinux.org
> Cc: dev@dpdk.org; yuanhan.liu@linux.intel.com; stable@dpdk.org; Stojaczyk,
> DariuszX
> Subject: [dpdk-dev] [PATCH] vhost: fix double free on shutdown
> 
> The vhost connection can be closed concurrently from 2 places:
>  * the connection thread itself
>  * rte_vhost_driver_unregister
> 
> The connection thread will terminate the connection if any recv error
> occurred. The unregister function will terminate the connection together
> with the thread. However, there is no sychronization between those two.
> The connection thread runs in the background without any mutex.

Isn't it already protected by vsocket->conn_mutex?

Thanks,
Jianfeng

> 
> The rte_vhost_driver_unregister now signals the connection thread
> to terminate itself and waits until it's killed.
> 
> Fixes: 65388b43f592 ("vhost: fix fd leaks for vhost-user server mode")
> Cc: yuanhan.liu@linux.intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
> Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
> ---
>  lib/librte_vhost/socket.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
> index 83befdced..46ac88efd 100644
> --- a/lib/librte_vhost/socket.c
> +++ b/lib/librte_vhost/socket.c
> @@ -735,7 +735,7 @@ rte_vhost_driver_unregister(const char *path)
>  {
>  	int i;
>  	int count;
> -	struct vhost_user_connection *conn, *next;
> +	struct vhost_user_connection *conn;
> 
>  	pthread_mutex_lock(&vhost_user.mutex);
> 
> @@ -752,22 +752,17 @@ rte_vhost_driver_unregister(const char *path)
>  			}
> 
>  			pthread_mutex_lock(&vsocket->conn_mutex);
> -			for (conn = TAILQ_FIRST(&vsocket->conn_list);
> -			     conn != NULL;
> -			     conn = next) {
> -				next = TAILQ_NEXT(conn, next);
> -
> -				fdset_del(&vhost_user.fdset, conn->connfd);
> -				RTE_LOG(INFO, VHOST_CONFIG,
> -					"free connfd = %d for device '%s'\n",
> -					conn->connfd, path);
> +			TAILQ_FOREACH(conn, &vsocket->conn_list, next) {
>  				close(conn->connfd);
> -				vhost_destroy_device(conn->vid);
> -				TAILQ_REMOVE(&vsocket->conn_list, conn,
> next);
> -				free(conn);
>  			}
>  			pthread_mutex_unlock(&vsocket->conn_mutex);
> 
> +			do {
> +				pthread_mutex_lock(&vsocket-
> >conn_mutex);
> +				conn = TAILQ_FIRST(&vsocket->conn_list);
> +				pthread_mutex_unlock(&vsocket-
> >conn_mutex);
> +			} while (conn != NULL);
> +
>  			pthread_mutex_destroy(&vsocket->conn_mutex);
>  			free(vsocket->path);
>  			free(vsocket);
> --
> 2.14.1