mac-learning: Change mac_learning_set_flood_vlans() to not take ownership.

These new semantics are less efficient in the case where the flood_vlans
actually changed, but that should be very rare.

There are no advantages to this change on its own, but upcoming commits
will add multiple layers between the code supplying the flood_vlans and
actually calling mac_learning_set_flood_vlans().  Consistency in this
multilayered interface seems valuable, and the rest of it does not transfer
ownership from the caller to the callee.

lib/bitmap.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,6 +53,12 @@ bitmap_allocate(size_t n_bits)
     return xzalloc(bitmap_n_bytes(n_bits));
 }
 
+static inline unsigned long *
+bitmap_clone(const unsigned long *bitmap, size_t n_bits)
+{
+    return xmemdup(bitmap, bitmap_n_bytes(n_bits));
+}
+
 static inline void
 bitmap_free(unsigned long *bitmap)
 {

lib/mac-learning.c

@@ -139,17 +139,19 @@ mac_learning_destroy(struct mac_learning *ml)
 }
 
 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
- * which all packets are flooded.  It takes ownership of the bitmap.  Returns
- * true if the set has changed from the previous value. */
+ * which all packets are flooded.  Returns true if the set has changed from the
+ * previous value. */
 bool
-mac_learning_set_flood_vlans(struct mac_learning *ml, unsigned long *bitmap)
+mac_learning_set_flood_vlans(struct mac_learning *ml,
+                             const unsigned long *bitmap)
 {
-    bool ret = vlan_bitmap_equal(ml->flood_vlans, bitmap);
-
-    bitmap_free(ml->flood_vlans);
-    ml->flood_vlans = bitmap;
-
-    return ret;
+    if (vlan_bitmap_equal(ml->flood_vlans, bitmap)) {
+        return false;
+    } else {
+        bitmap_free(ml->flood_vlans);
+        ml->flood_vlans = vlan_bitmap_clone(bitmap);
+        return true;
+    }
 }
 
 static bool

lib/mac-learning.h

@@ -96,7 +96,7 @@ void mac_learning_wait(struct mac_learning *);
 
 /* Configuration. */
 bool mac_learning_set_flood_vlans(struct mac_learning *,
-                                  unsigned long *bitmap);
+                                  const unsigned long *bitmap);
 
 /* Learning. */
 bool mac_learning_may_learn(const struct mac_learning *,

lib/vlan-bitmap.h

@@ -37,4 +37,11 @@ vlan_bitmap_contains(const unsigned long *vlans, uint16_t vid)
     return !vlans || bitmap_is_set(vlans, vid);
 }
 
+/* Returns a new copy of 'vlans'. */
+static inline unsigned long *
+vlan_bitmap_clone(const unsigned long *vlans)
+{
+    return vlans ? bitmap_clone(vlans, 4096) : NULL;
+}
+
 #endif /* lib/vlan-bitmap.h */

vswitchd/bridge.c

@@ -3621,6 +3621,7 @@ mirror_reconfigure(struct bridge *br)
         bridge_flush(br);
         mac_learning_flush(br->ml);
     }
+    free(rspan_vlans);
 }
 
 static void