Re: [PATCH V4] multipathd: release uxsocket and resource when cancel thread

["Benjamin Marzinski" <bmarzins@redhat.com>]

On Wed, Jan 17, 2018 at 08:15:05AM +0000, Wuchongyun wrote:
> Hi Matin,
> I think it's a good idea to move the close(ux_sock) call further up to avoid new clients trying to connect, Below is the new patch for your comment. Please help to review. Thanks. 

Looks good.

Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
 
> Issue description: we meet this issue: when multipathd initilaze and
> call uxsock_listen to create unix domain socket, but return -1 and
> the errno is 98 and then the uxsock_listen return null. After multipathd
> startup we can't receive any user's multipathd commands to finish the
> new multipath creation or any operations any more!
> 
> We found that uxlsnr thread's cleanup function not close the sockets
> also not release the clients when cancel thread, the domain socket
> will be release by the system. In any special environment like the
> machine's load is very heavy or any situations, the system may not close
> the old domain socket when we try to create and bind the new domain
> socket may return errno:98(Address already in use).
> 
> And also we make some experiments:
> in uxsock_cleanup if we close the ux_sock first and then immdediately
> call ux_socket_listen to create new ux_sock and initialization will be
> OK; if we don't close the ux_sock and call ux_socket_listen will return
> -1 and errno = 98.
> 
> So we believe that close uxsocket and release clients  when cancel
> thread can make sure of that new starting multipathd thread can
> create new uxsocket successfully, also can receive multipathd commands
> properly. And this path can fix clients' memory leak too.
> 
> Signed-off-by: Chongyun Wu <wu.chongyun@h3c.com>
> ---
>  multipathd/uxlsnr.c |   30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
> index 98ac25a..8aa0f83 100644
> --- a/multipathd/uxlsnr.c
> +++ b/multipathd/uxlsnr.c
> @@ -102,14 +102,21 @@ static void new_client(int ux_sock)
>  /*
>   * kill off a dead client
>   */
> -static void dead_client(struct client *c)
> +static void _dead_client(struct client *c)
>  {
> -	pthread_mutex_lock(&client_lock);
> +	int fd = c->fd;
>  	list_del_init(&c->node);
> -	pthread_mutex_unlock(&client_lock);
> -	close(c->fd);
>  	c->fd = -1;
>  	FREE(c);
> +	close(fd);
> +}
> +
> +static void dead_client(struct client *c)
> +{
> +	pthread_cleanup_push(cleanup_lock, &client_lock);
> +	pthread_mutex_lock(&client_lock);
> +	_dead_client(c);
> +	pthread_cleanup_pop(1);
>  }
>  
>  void free_polls (void)
> @@ -139,6 +146,18 @@ void check_timeout(struct timespec start_time, char *inbuf,
>  
>  void uxsock_cleanup(void *arg)
>  {
> +	struct client *client_loop;
> +	struct client *client_tmp;
> +	int ux_sock = (int)arg;
> +
> +	close(ux_sock);
> +
> +	pthread_mutex_lock(&client_lock);
> +	list_for_each_entry_safe(client_loop, client_tmp, &clients, node) {
> +		_dead_client(client_loop);
> +	}
> +	pthread_mutex_unlock(&client_lock);
> +
>  	cli_exit();
>  	free_polls();
>  }
> @@ -162,7 +181,7 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
>  		return NULL;
>  	}
>  
> -	pthread_cleanup_push(uxsock_cleanup, NULL);
> +	pthread_cleanup_push(uxsock_cleanup, (void *)ux_sock);
>  
>  	condlog(3, "uxsock: startup listener");
>  	polls = (struct pollfd *)MALLOC((MIN_POLLS + 1) * sizeof(struct pollfd));
> @@ -300,6 +319,5 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
>  	}
>  
>  	pthread_cleanup_pop(1);
> -	close(ux_sock);
>  	return NULL;
>  }
> -- 
> 1.7.9.5