Re: [PATCH] vhost: fix deadlock when vhost unregister.

[Ye Xiaolong <xiaolong.ye@intel.com>]

Hi,

On 01/11, sunwenjie wrote:
>    When rte_vhost_driver_unregister  delete the connection fd,
>    fdset_try_del will always try and donot release the
>    vhostuser.mutex if the fd is busy, but the fdset_event_dispatch
>    will set the  fd to busy and call vhost_user_msg_handler to get
>    vhostuser.mutex, which will  cause deadlock. Unlock the
>    vhost_user.mutexif fdset_try_del fail and relock it when retry.
>
>    Signed-off-by: findtheonlway <findtheonlyway@gmail.com>
>    Signed-off-by: sunwenjie <sunwenjie@didichuxing.com>

The commit log and Signed-off-by tage should not be indented, and you should
get you commit log checked by `./devtools/check-git-log.sh -1`, and fix all the
errors it shows.

Btw, I think this is your v2 patch, and you should add the v2 tag in the
subject.

Thanks,
Xiaolong

>---
> lib/librte_vhost/socket.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
>index 9cf34ad17..7959c5ece 100644
>--- a/lib/librte_vhost/socket.c
>+++ b/lib/librte_vhost/socket.c
>@@ -961,13 +961,13 @@ rte_vhost_driver_unregister(const char *path)
> 	int count;
> 	struct vhost_user_connection *conn, *next;
> 
>+again:
> 	pthread_mutex_lock(&vhost_user.mutex);
> 
> 	for (i = 0; i < vhost_user.vsocket_cnt; i++) {
> 		struct vhost_user_socket *vsocket = vhost_user.vsockets[i];
> 
> 		if (!strcmp(vsocket->path, path)) {
>-again:
> 			pthread_mutex_lock(&vsocket->conn_mutex);
> 			for (conn = TAILQ_FIRST(&vsocket->conn_list);
> 			     conn != NULL;
>@@ -981,6 +981,7 @@ rte_vhost_driver_unregister(const char *path)
> 				 */
> 				if (fdset_try_del(&vhost_user.fdset,
> 						  conn->connfd) == -1) {
>+					pthread_mutex_unlock(&vhost_user.mutex);
> 					pthread_mutex_unlock(
> 							&vsocket->conn_mutex);
> 					goto again;
>-- 
>2.20.1
>