[Cluster-devel] GPF in dlm_lowcomms_stop

[dann frazier]

On Fri, Mar 30, 2012 at 12:42:40PM -0400, David Teigland wrote:
> On Fri, Mar 30, 2012 at 11:42:56AM -0400, David Teigland wrote:
> > Hi Dan, I'm not very familiar with this code either, but I've talked with
> > Chrissie and she suggested we try something like this:

Yeah, that's the mechanism I was thinking of as well.

> A second version that addresses a potentially similar problem in
> start.

Oh, good catch! I hadn't considered that path.

Reviewed-by: dann frazier <dann.frazier at canonical.com>

> 
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index 133ef6d..5c1b0e3 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -142,6 +142,7 @@ struct writequeue_entry {
>  
>  static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
>  static int dlm_local_count;
> +static int dlm_allow_conn;
>  
>  /* Work queues */
>  static struct workqueue_struct *recv_workqueue;
> @@ -710,6 +711,13 @@ static int tcp_accept_from_sock(struct connection *con)
>  	struct connection *newcon;
>  	struct connection *addcon;
>  
> +	mutex_lock(&connections_lock);
> +	if (!dlm_allow_conn) {
> +		mutex_unlock(&connections_lock);
> +		return -1;
> +	}
> +	mutex_unlock(&connections_lock);
> +
>  	memset(&peeraddr, 0, sizeof(peeraddr));
>  	result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_STREAM,
>  				  IPPROTO_TCP, &newsock);
> @@ -1503,6 +1511,7 @@ void dlm_lowcomms_stop(void)
>  	   socket activity.
>  	*/
>  	mutex_lock(&connections_lock);
> +	dlm_allow_conn = 0;
>  	foreach_conn(stop_conn);
>  	mutex_unlock(&connections_lock);
>  
> @@ -1530,7 +1539,7 @@ int dlm_lowcomms_start(void)
>  	if (!dlm_local_count) {
>  		error = -ENOTCONN;
>  		log_print("no local IP address has been set");
> -		goto out;
> +		goto fail;
>  	}
>  
>  	error = -ENOMEM;
> @@ -1538,7 +1547,13 @@ int dlm_lowcomms_start(void)
>  				      __alignof__(struct connection), 0,
>  				      NULL);
>  	if (!con_cache)
> -		goto out;
> +		goto fail;
> +
> +	error = work_start();
> +	if (error)
> +		goto fail_destroy;
> +
> +	dlm_allow_conn = 1;
>  
>  	/* Start listening */
>  	if (dlm_config.ci_protocol == 0)
> @@ -1548,20 +1563,17 @@ int dlm_lowcomms_start(void)
>  	if (error)
>  		goto fail_unlisten;
>  
> -	error = work_start();
> -	if (error)
> -		goto fail_unlisten;
> -
>  	return 0;
>  
>  fail_unlisten:
> +	dlm_allow_conn = 0;
>  	con = nodeid2con(0,0);
>  	if (con) {
>  		close_connection(con, false);
>  		kmem_cache_free(con_cache, con);
>  	}
> +fail_destroy:
>  	kmem_cache_destroy(con_cache);
> -
> -out:
> +fail:
>  	return error;
>  }