dlm: prevent connections during shutdown

During lowcomms shutdown, a new connection could possibly
be created, and attempt to use a workqueue that's been
destroyed.  Similarly, during startup, a new connection
could attempt to use a workqueue that's not been set up
yet.  Add a global variable to indicate when new connections
are allowed.

Based on patch by: Christine Caulfield <ccaulfie@redhat.com>

Reported-by: dann frazier <dann.frazier@canonical.com>
Reviewed-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: David Teigland <teigland@redhat.com>

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 133ef6d..5c1b0e3 100644 (file)
--- 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;
 }