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platform: fix caching for link types

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This bug was present since a long time, however libnl3-v3.2.23
(commit fdd1ba220dd7b780400e9d0652cde80e59f63572) changed the returned
family of bridge link objects, which breaks NetworkManager.

This resulted in error messages such as:

  DBG<4>            object.c:207  nl_object_get: New reference to object 0x19c34b0, total 2
  DBG<5>        route/link.c:895  link_keygen: link 0x19c34b0 key (dev 9 fam 7) keysz 8, hash 0x2b2
  DBG<2>         hashtable.c:127  nl_hash_table_add: Warning: Add to hashtable found duplicate...
  DBG<4>            object.c:221  nl_object_put: Returned object reference 0x19c34b0, 1 remaining
  NetworkManager[17745]: <error> [1392114373.475432] [platform/nm-linux-platform.c:1328] event_notification(): netlink cache error: Object exists

Even before the change of libnl, I saw the following error lines
 <debug> [...] [platform/nm-linux-platform.c:1216] event_notification(): netlink event (type 16) for link: virbr0 (4)
 <error> [...] [platform/nm-linux-platform.c:1265] event_notification(): netlink cache error: Object exists
Hence, the caching mechanism for libnl objects already had a bug.

For rtnl link objects, the identifier consists of family and ifindex.
Since in upper layers, we don't easily know the family, we need a way to find
the objects inside the cache. We do this, by only caching links of family
AF_UNSPEC.

Objects that we receive via event_notification() are never cached. They are only used
to trigger refetching the kernel_object. Their family is irrelevant, we
only need to know, that something about this ifindex changed.

For objects retrieved via get_kernel_object(), we only get link objects of
family AF_UNSPEC or AF_BRIDGE. In any case, we reset (coerce) their family
before caching. This way, inside the link cache, there are only objects with
(coerced) family AF_UNSPEC. We loose the information, which family the
link had, however we don't need it anyway.

https://bugzilla.gnome.org/show_bug.cgi?id=719905
https://bugzilla.redhat.com/show_bug.cgi?id=1063290

Duplicates:
https://bugzilla.gnome.org/show_bug.cgi?id=724225
https://bugzilla.redhat.com/show_bug.cgi?id=1063800

Signed-off-by: Thomas Haller <thaller@redhat.com>
This commit is contained in:
Thomas Haller 2014-02-11 20:16:03 +01:00
parent a5f3fcae29
commit a6f9266555
1 changed files with 37 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

52
src/platform/nm-linux-platform.c
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@ -189,26 +189,47 @@ object_type_from_nl_object (const struct nl_object *object)
return UNKNOWN_OBJECT_TYPE;
}
/* libnl inclues LINK_ATTR_FAMILY in oo_id_attrs of link_obj_ops and thus
* refuses to search for items that lack this attribute. I believe this is a
* bug or a bad design at the least. Address family is not an identifying
* attribute of a network interface and IMO is not an attribute of a network
* interface at all.
*/
static void
_nl_link_family_unset (struct nl_object *obj, int *family)
{
if (!obj || object_type_from_nl_object (obj) != LINK)
*family = AF_UNSPEC;
else {
*family = rtnl_link_get_family ((struct rtnl_link *) obj);
/* Always explicitly set the family to AF_UNSPEC, even if rtnl_link_get_family() might
* already return %AF_UNSPEC. The reason is, that %AF_UNSPEC is the default family
* and libnl nl_object_identical() function will only succeed, if the family is
* explicitly set (which we cannot be sure, unless setting it). */
rtnl_link_set_family ((struct rtnl_link *) obj, AF_UNSPEC);
}
}
/* In our link cache, we coerce the family of all link objects to AF_UNSPEC.
* Thus, before searching for an object, we fixup @needle to have the right
* id (by resetting the family). */
static struct nl_object *
nm_nl_cache_search (struct nl_cache *cache, struct nl_object *needle)
{
if (object_type_from_nl_object (needle) == LINK)
rtnl_link_set_family ((struct rtnl_link *) needle, AF_UNSPEC);
int family;
struct nl_object *obj;
return nl_cache_search (cache, needle);
_nl_link_family_unset (needle, &family);
obj = nl_cache_search (cache, needle);
if (family != AF_UNSPEC) {
/* restore the family of the @needle instance. If the family was
* unset before, we cannot make it unset again. Thus, in that case
* we cannot undo _nl_link_family_unset() entirely. */
rtnl_link_set_family ((struct rtnl_link *) needle, family);
}
return obj;
}
#define nl_cache_search nm_nl_cache_search
/* Ask the kernel for an object identical (as in nl_cache_identical) to the
* needle argument. This is a kernel counterpart for nl_cache_search.
*
* libnl 3.2 doesn't seem to provide such functionality.
* The returned object must be freed by the caller with nl_object_put().
*/
static struct nl_object *
get_kernel_object (struct nl_sock *sock, struct nl_object *needle)
@ -225,6 +246,7 @@ get_kernel_object (struct nl_sock *sock, struct nl_object *needle)
nle = rtnl_link_get_kernel (sock, ifindex, name, (struct rtnl_link **) &kernel_object);
switch (nle) {
case -NLE_SUCCESS:
_nl_link_family_unset (kernel_object, &nle);
return kernel_object;
case -NLE_NODEV:
return NULL;
@ -1128,7 +1150,7 @@ refresh_object (NMPlatform *platform, struct nl_object *object, gboolean removed
int nle;
cache = choose_cache (platform, object);
cached_object = nl_cache_search (choose_cache (platform, object), object);
cached_object = nm_nl_cache_search (cache, object);
kernel_object = get_kernel_object (priv->nlh, object);
if (removed) {
@ -1223,7 +1245,7 @@ delete_object (NMPlatform *platform, struct nl_object *obj)
* for delete_kernel_object() and we need to search the cache first. If
* that problem is fixed, we can use 'object' directly.
*/
cached_object = nl_cache_search (choose_cache (platform, object), object);
cached_object = nm_nl_cache_search (choose_cache (platform, object), object);
g_return_val_if_fail (cached_object, FALSE);
nle = delete_kernel_object (priv->nlh, cached_object);
@ -1285,7 +1307,7 @@ event_notification (struct nl_msg *msg, gpointer user_data)
g_return_val_if_fail (object, NL_OK);
cache = choose_cache (platform, object);
cached_object = nl_cache_search (cache, object);
cached_object = nm_nl_cache_search (cache, object);
kernel_object = get_kernel_object (priv->nlh, object);
/* Just for debugging */
@ -1321,7 +1343,7 @@ event_notification (struct nl_msg *msg, gpointer user_data)
* already removed and announced.
*/
if (event == RTM_DELLINK) {
if (!link_is_announceable (platform, (struct rtnl_link *) object))
if (!link_is_announceable (platform, (struct rtnl_link *) cached_object))
return NL_OK;
}
announce_object (platform, cached_object, REMOVED, NM_PLATFORM_REASON_EXTERNAL);