1 files changed, 39 insertions, 22 deletions

diff --git a/balloon.c b/balloon.c
index 248c1b50a9..f56fdc1c4b 100644
--- a/balloon.c
+++ b/balloon.c
@@ -1,7 +1,9 @@
 /*
- * QEMU System Emulator
+ * Generic Balloon handlers and management
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (C) 2011 Red Hat, Inc.
+ * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -30,44 +32,53 @@
 #include "balloon.h"
 #include "trace.h"
 
+static QEMUBalloonEvent *balloon_event_fn;
+static QEMUBalloonStatus *balloon_stat_fn;
+static void *balloon_opaque;
 
-static QEMUBalloonEvent *qemu_balloon_event;
-void *qemu_balloon_event_opaque;
-
-void qemu_add_balloon_handler(QEMUBalloonEvent *func, void *opaque)
+int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
+                             QEMUBalloonStatus *stat_func, void *opaque)
 {
-    qemu_balloon_event = func;
-    qemu_balloon_event_opaque = opaque;
+    if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
+        /* We're already registered one balloon handler.  How many can
+         * a guest really have?
+         */
+        error_report("Another balloon device already registered");
+        return -1;
+    }
+    balloon_event_fn = event_func;
+    balloon_stat_fn = stat_func;
+    balloon_opaque = opaque;
+    return 0;
 }
 
-int qemu_balloon(ram_addr_t target, MonitorCompletion cb, void *opaque)
+static int qemu_balloon(ram_addr_t target)
 {
-    if (qemu_balloon_event) {
-        trace_balloon_event(qemu_balloon_event_opaque, target);
-        qemu_balloon_event(qemu_balloon_event_opaque, target, cb, opaque);
-        return 1;
-    } else {
+    if (!balloon_event_fn) {
         return 0;
     }
+    trace_balloon_event(balloon_opaque, target);
+    balloon_event_fn(balloon_opaque, target);
+    return 1;
 }
 
-int qemu_balloon_status(MonitorCompletion cb, void *opaque)
+static int qemu_balloon_status(MonitorCompletion cb, void *opaque)
 {
-    if (qemu_balloon_event) {
-        qemu_balloon_event(qemu_balloon_event_opaque, 0, cb, opaque);
-        return 1;
-    } else {
+    if (!balloon_stat_fn) {
         return 0;
     }
+    balloon_stat_fn(balloon_opaque, cb, opaque);
+    return 1;
 }
 
 static void print_balloon_stat(const char *key, QObject *obj, void *opaque)
 {
     Monitor *mon = opaque;
 
-    if (strcmp(key, "actual"))
+    if (strcmp(key, "actual")) {
         monitor_printf(mon, ",%s=%" PRId64, key,
                        qint_get_int(qobject_to_qint(obj)));
+    }
 }
 
 void monitor_print_balloon(Monitor *mon, const QObject *data)
@@ -75,9 +86,9 @@ void monitor_print_balloon(Monitor *mon, const QObject *data)
     QDict *qdict;
 
     qdict = qobject_to_qdict(data);
-    if (!qdict_haskey(qdict, "actual"))
+    if (!qdict_haskey(qdict, "actual")) {
         return;
-
+    }
     monitor_printf(mon, "balloon: actual=%" PRId64,
                    qdict_get_int(qdict, "actual") >> 20);
     qdict_iter(qdict, print_balloon_stat, mon);
@@ -129,6 +140,7 @@ int do_info_balloon(Monitor *mon, MonitorCompletion cb, void *opaque)
 int do_balloon(Monitor *mon, const QDict *params,
 	       MonitorCompletion cb, void *opaque)
 {
+    int64_t target;
     int ret;
 
     if (kvm_enabled() && !kvm_has_sync_mmu()) {
@@ -136,7 +148,12 @@ int do_balloon(Monitor *mon, const QDict *params,
         return -1;
     }
 
-    ret = qemu_balloon(qdict_get_int(params, "value"), cb, opaque);
+    target = qdict_get_int(params, "value");
+    if (target <= 0) {
+        qerror_report(QERR_INVALID_PARAMETER_VALUE, "target", "a size");
+        return -1;
+    }
+    ret = qemu_balloon(target);
     if (ret == 0) {
         qerror_report(QERR_DEVICE_NOT_ACTIVE, "balloon");
         return -1;