From f8e19f805f7d4e2e2a8588d83c284ec43ac3d956 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Thu, 11 Mar 2021 08:24:47 +0100
Subject: [PATCH] libnm: make NMLldpNeighbor ref-counting thread-safe

At least ref-counting should be thread safe for our public API.

Note that NMLldpNeighbor has no public API for mutating a neighbor
instance. Especially for immutable types, it is very attractive that
ref-counting is thread-safe.

Also use slice allocator for NMLldpNeighbor structs.
---
 src/libnm-client-impl/nm-device.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/src/libnm-client-impl/nm-device.c b/src/libnm-client-impl/nm-device.c
index 8632b0c316..8d3c2bb607 100644
--- a/src/libnm-client-impl/nm-device.c
+++ b/src/libnm-client-impl/nm-device.c
@@ -134,7 +134,7 @@ static NMLldpNeighbor *nm_lldp_neighbor_dup(NMLldpNeighbor *neighbor);
 /*****************************************************************************/
 
 struct _NMLldpNeighbor {
-    guint       refcount;
+    int         refcount;
     GHashTable *attrs;
 };
 
@@ -2881,10 +2881,14 @@ nm_lldp_neighbor_new(void)
 {
     NMLldpNeighbor *neigh;
 
-    neigh           = g_new0(NMLldpNeighbor, 1);
-    neigh->refcount = 1;
-    neigh->attrs =
-        g_hash_table_new_full(nm_str_hash, g_str_equal, g_free, (GDestroyNotify) g_variant_unref);
+    neigh  = g_slice_new(NMLldpNeighbor);
+    *neigh = (NMLldpNeighbor){
+        .refcount = 1,
+        .attrs    = g_hash_table_new_full(nm_str_hash,
+                                       g_str_equal,
+                                       g_free,
+                                       (GDestroyNotify) g_variant_unref),
+    };
 
     return neigh;
 }
@@ -2912,6 +2916,8 @@ nm_lldp_neighbor_dup(NMLldpNeighbor *neighbor)
  *
  * Increases the reference count of the object.
  *
+ * Since 1.32, ref-counting of #NMLldpNeighbor is thread-safe.
+ *
  * Since: 1.2
  **/
 void
@@ -2919,7 +2925,7 @@ nm_lldp_neighbor_ref(NMLldpNeighbor *neighbor)
 {
     g_return_if_fail(NM_IS_LLDP_NEIGHBOR(neighbor));
 
-    neighbor->refcount++;
+    g_atomic_int_inc(&neighbor->refcount);
 }
 
 /**
@@ -2929,6 +2935,8 @@ nm_lldp_neighbor_ref(NMLldpNeighbor *neighbor)
  * Decreases the reference count of the object.  If the reference count
  * reaches zero, the object will be destroyed.
  *
+ * Since 1.32, ref-counting of #NMLldpNeighbor is thread-safe.
+ *
  * Since: 1.2
  **/
 void
@@ -2936,9 +2944,9 @@ nm_lldp_neighbor_unref(NMLldpNeighbor *neighbor)
 {
     g_return_if_fail(NM_IS_LLDP_NEIGHBOR(neighbor));
 
-    if (--neighbor->refcount == 0) {
+    if (g_atomic_int_dec_and_test(&neighbor->refcount)) {
         g_hash_table_unref(neighbor->attrs);
-        g_free(neighbor);
+        nm_g_slice_free(neighbor);
     }
 }