Fix: sbd-cluster: stop dispatching cmap if disconnected

If cmap socket is in HUP state, attempt to dispatch incoming events
will trigger the callback again and cause infinite loop with high
CPU load.
Added check should solve this by destroying the cmap connection and
removing it from the main loop.

Author: skazi0

src/sbd-cluster.c

@@ -35,6 +35,10 @@
 
 #if CHECK_TWO_NODE
 #include <glib-unix.h>
+// available since glib 2.58
+#ifndef G_SOURCE_FUNC
+#define G_SOURCE_FUNC(f) ((GSourceFunc) (void (*)(void)) (f))
+#endif
 #endif
 
 #include "sbd.h"
@@ -58,6 +62,7 @@ static crm_cluster_t cluster;
 static gboolean sbd_remote_check(gpointer user_data);
 static long unsigned int find_pacemaker_remote(void);
 static void sbd_membership_destroy(gpointer user_data);
+static void cmap_destroy(void);
 
 
 #if SUPPORT_PLUGIN
@@ -168,10 +173,19 @@ static void sbd_cmap_notify_fn(
 }
 
 static gboolean
-cmap_dispatch_callback (gpointer user_data)
+cmap_dispatch_callback (gint cmap_fd,
+                        GIOCondition condition,
+                        gpointer user_data)
 {
+    /* CMAP connection lost */
+    if (condition & G_IO_HUP) {
+        cl_log(LOG_WARNING, "CMAP service connection lost\n");
+        cmap_destroy();
+        /* remove the source from the main loop */
+        return G_SOURCE_REMOVE;
+    }
     cmap_dispatch(cmap_handle, CS_DISPATCH_ALL);
-    return TRUE;
+    return G_SOURCE_CONTINUE;
 }
 
 static void
@@ -222,7 +236,7 @@ sbd_get_two_node(void)
             cl_log(LOG_WARNING, "Couldn't create source for cmap\n");
             goto out;
         }
-        g_source_set_callback(cmap_source, cmap_dispatch_callback, NULL, NULL);
+        g_source_set_callback(cmap_source, G_SOURCE_FUNC(cmap_dispatch_callback), NULL, NULL);
         g_source_attach(cmap_source, NULL);
     }