cache_mngr: add include callback v2

This patch adds change_func_v2_t to add a more detailed callback in
case of a cache change. The change function is registered using the new
nl_cache_mngr_add_cache_v2. In case the new change function is set,
nl_cache_include_v2 and thus cache_include_v2 will be used to perform the cache
inclusion.

The parameter of change_func_v2_t are the following:
* struct nl_cache * => cache
* struct nl_object * => the old/deleted nl_object
* struct nl_object * => the new nl_object
* uint64_t => the result of nl_object_diff64 in case of a change
* int => NL_ACT_*
* void * => data

#71
http://lists.infradead.org/pipermail/libnl/2016-September/002214.html
http://lists.infradead.org/pipermail/libnl/2016-October/002229.html
http://lists.infradead.org/pipermail/libnl/2016-November/002250.html

Author: Tobias Jungel

include/netlink-private/cache-api.h

@@ -237,7 +237,8 @@ struct nl_cache_ops
 	 * @see nl_cache_include()
 	 */
 	int   (*co_include_event)(struct nl_cache *cache, struct nl_object *obj,
-				  change_func_t change_cb, void *data);
+				  change_func_t change_cb, change_func_v2_t change_cb_v2,
+				  void *data);
 
 	void (*reserved_1)(void);
 	void (*reserved_2)(void);

include/netlink-private/types.h

@@ -99,6 +99,7 @@ struct nl_cache_assoc
 {
 	struct nl_cache *	ca_cache;
 	change_func_t		ca_change;
+	change_func_v2_t	ca_change_v2;
 	void *			ca_change_data;
 };
 

include/netlink/cache.h

@@ -35,6 +35,8 @@ enum {
 
 struct nl_cache;
 typedef void (*change_func_t)(struct nl_cache *, struct nl_object *, int, void *);
+typedef void (*change_func_v2_t)(struct nl_cache *, struct nl_object *old_obj,
+	      struct nl_object *new_obj, uint64_t, int, void *);
 
 /**
  * @ingroup cache
@@ -88,6 +90,10 @@ extern int			nl_cache_include(struct nl_cache *,
 						 struct nl_object *,
 						 change_func_t,
 						 void *);
+extern int			nl_cache_include_v2(struct nl_cache *,
+						    struct nl_object *,
+						    change_func_v2_t,
+						    void *);
 extern void			nl_cache_set_arg1(struct nl_cache *, int);
 extern void			nl_cache_set_arg2(struct nl_cache *, int);
 extern void			nl_cache_set_flags(struct nl_cache *, unsigned int);
@@ -154,6 +160,9 @@ extern int			nl_cache_mngr_add(struct nl_cache_mngr *,
 extern int			nl_cache_mngr_add_cache(struct nl_cache_mngr *mngr,
 							struct nl_cache *cache,
 							change_func_t cb, void *data);
+extern int			nl_cache_mngr_add_cache_v2(struct nl_cache_mngr *mngr,
+							   struct nl_cache *cache,
+							   change_func_v2_t cb, void *data);
 extern int			nl_cache_mngr_get_fd(struct nl_cache_mngr *);
 extern int			nl_cache_mngr_poll(struct nl_cache_mngr *,
 						   int);

lib/cache.c

@@ -784,41 +784,66 @@ int nl_cache_pickup(struct nl_sock *sk, struct nl_cache *cache)
 }
 
 static int cache_include(struct nl_cache *cache, struct nl_object *obj,
-			 struct nl_msgtype *type, change_func_t cb, void *data)
+			 struct nl_msgtype *type, change_func_t cb,
+			 change_func_v2_t cb_v2, void *data)
 {
 	struct nl_object *old;
+	struct nl_object *clone = NULL;
+	uint64_t diff;
 
 	switch (type->mt_act) {
 	case NL_ACT_NEW:
 	case NL_ACT_DEL:
 		old = nl_cache_search(cache, obj);
 		if (old) {
+			if (cb_v2 && old->ce_ops->oo_update) {
+				clone = nl_object_clone(old);
+				diff = nl_object_diff64(old, obj);
+			}
 			/*
 			 * Some objects types might support merging the new
 			 * object with the old existing cache object.
 			 * Handle them first.
 			 */
 			if (nl_object_update(old, obj) == 0) {
-				if (cb)
+				if (cb_v2) {
+					cb_v2(cache, clone, obj, diff,
+					      NL_ACT_CHANGE, data);
+					nl_object_put(clone);
+				} else if (cb)
 					cb(cache, old, NL_ACT_CHANGE, data);
 				nl_object_put(old);
 				return 0;
 			}
+			nl_object_put(clone);
 
 			nl_cache_remove(old);
 			if (type->mt_act == NL_ACT_DEL) {
-				if (cb)
+				if (cb_v2)
+					cb_v2(cache, old, NULL, 0, NL_ACT_DEL,
+					      data);
+				else if (cb)
 					cb(cache, old, NL_ACT_DEL, data);
 				nl_object_put(old);
 			}
 		}
 
 		if (type->mt_act == NL_ACT_NEW) {
 			nl_cache_move(cache, obj);
-			if (old == NULL && cb)
-				cb(cache, obj, NL_ACT_NEW, data);
-			else if (old) {
-				if (nl_object_diff(old, obj) && cb)
+			if (old == NULL) {
+				if (cb_v2) {
+					cb_v2(cache, NULL, obj, 0, NL_ACT_NEW,
+					      data);
+				} else if (cb)
+					cb(cache, obj, NL_ACT_NEW, data);
+			} else if (old) {
+				uint64_t diff = 0;
+				if (cb || cb_v2)
+					diff = nl_object_diff64(old, obj);
+				if (diff && cb_v2) {
+					cb_v2(cache, old, obj, diff, NL_ACT_CHANGE,
+					      data);
+				} else if (diff && cb)
 					cb(cache, obj, NL_ACT_CHANGE, data);
 
 				nl_object_put(old);
@@ -845,7 +870,27 @@ int nl_cache_include(struct nl_cache *cache, struct nl_object *obj,
 	for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
 		if (ops->co_msgtypes[i].mt_id == obj->ce_msgtype)
 			return cache_include(cache, obj, &ops->co_msgtypes[i],
-					     change_cb, data);
+					     change_cb, NULL, data);
+
+	NL_DBG(3, "Object %p does not seem to belong to cache %p <%s>\n",
+	       obj, cache, nl_cache_name(cache));
+
+	return -NLE_MSGTYPE_NOSUPPORT;
+}
+
+int nl_cache_include_v2(struct nl_cache *cache, struct nl_object *obj,
+			change_func_v2_t change_cb, void *data)
+{
+	struct nl_cache_ops *ops = cache->c_ops;
+	int i;
+
+	if (ops->co_obj_ops != obj->ce_ops)
+		return -NLE_OBJ_MISMATCH;
+
+	for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
+		if (ops->co_msgtypes[i].mt_id == obj->ce_msgtype)
+			return cache_include(cache, obj, &ops->co_msgtypes[i],
+						NULL, change_cb, data);
 
 	NL_DBG(3, "Object %p does not seem to belong to cache %p <%s>\n",
 	       obj, cache, nl_cache_name(cache));
@@ -857,7 +902,12 @@ static int resync_cb(struct nl_object *c, struct nl_parser_param *p)
 {
 	struct nl_cache_assoc *ca = p->pp_arg;
 
-	return nl_cache_include(ca->ca_cache, c, ca->ca_change, ca->ca_change_data);
+	if (ca->ca_change_v2)
+		return nl_cache_include_v2(ca->ca_cache, c, ca->ca_change_v2,
+					   ca->ca_change_data);
+	else
+		return nl_cache_include(ca->ca_cache, c, ca->ca_change,
+					ca->ca_change_data);
 }
 
 int nl_cache_resync(struct nl_sock *sk, struct nl_cache *cache,

lib/cache_mngr.c

@@ -60,9 +60,15 @@ static int include_cb(struct nl_object *obj, struct nl_parser_param *p)
 
 	if (ops->co_include_event)
 		return ops->co_include_event(ca->ca_cache, obj, ca->ca_change,
+					     ca->ca_change_v2,
 					     ca->ca_change_data);
-	else
-		return nl_cache_include(ca->ca_cache, obj, ca->ca_change, ca->ca_change_data);
+	else {
+		if (ca->ca_change_v2)
+			return nl_cache_include_v2(ca->ca_cache, obj, ca->ca_change_v2, ca->ca_change_data);
+		else
+			return nl_cache_include(ca->ca_cache, obj, ca->ca_change, ca->ca_change_data);
+	}
+
 }
 
 static int event_input(struct nl_msg *msg, void *arg)
@@ -194,6 +200,70 @@ int nl_cache_mngr_alloc(struct nl_sock *sk, int protocol, int flags,
 	return err;
 }
 
+/**
+ * Set change_func_v2 for cache manager
+ * @arg mngr		Cache manager.
+ * @arg cache		Cache associated with the callback
+ * @arg cb		Function to be called upon changes.
+ * @arg data		Argument passed on to change callback
+ *
+ * Adds callback change_func_v2 to a registered cache. This callback provides
+ * in like the standard change_func the added or remove netlink object. In case
+ * of a change the old and the new object is provided as well as the according
+ * diff. If this callback is registered this has a higher priority then the
+ * change_func registered during cache registration. Hence only one callback is
+ * executed.
+ *
+ * The first netlink object in the callback is refering to the old object and
+ * the second to the new. This means on NL_ACT_CHANGE the first is the previous
+ * object in the cache and the second the updated version. On NL_ACT_DEL the
+ * first is the deleted object the second is NULL. On NL_ACT_NEW the first is
+ * NULL and the second the new netlink object.
+ *
+ * The user is responsible for calling nl_cache_mngr_poll() or monitor
+ * the socket and call nl_cache_mngr_data_ready() to allow the library
+ * to process netlink notification events.
+ *
+ * @see nl_cache_mngr_poll()
+ * @see nl_cache_mngr_data_ready()
+ *
+ * @return 0 on success or a negative error code.
+ * @return -NLE_PROTO_MISMATCH Protocol mismatch between cache manager and
+ * 			       cache type
+ * @return -NLE_OPNOTSUPP Cache type does not support updates
+ * @return -NLE_RANGE Cache of this type is not registered
+ */
+static int nl_cache_mngr_set_change_func_v2(struct nl_cache_mngr *mngr,
+					    struct nl_cache *cache,
+					    change_func_v2_t cb, void *data)
+{
+	struct nl_cache_ops *ops;
+	int i;
+
+	ops = cache->c_ops;
+	if (!ops)
+		return -NLE_INVAL;
+
+	if (ops->co_protocol != mngr->cm_protocol)
+		return -NLE_PROTO_MISMATCH;
+
+	if (ops->co_groups == NULL)
+		return -NLE_OPNOTSUPP;
+
+	for (i = 0; i < mngr->cm_nassocs; i++)
+		if (mngr->cm_assocs[i].ca_cache == cache)
+			break;
+
+	if (i >= mngr->cm_nassocs) {
+		return -NLE_RANGE;
+	}
+
+	mngr->cm_assocs[i].ca_change_v2 = cb;
+	mngr->cm_assocs[i].ca_change_data = data;
+
+	return 0;
+}
+
 /**
  * Add cache to cache manager
  * @arg mngr		Cache manager.
@@ -291,6 +361,41 @@ int nl_cache_mngr_add_cache(struct nl_cache_mngr *mngr, struct nl_cache *cache,
 	return err;
 }
 
+/**
+ * Add cache to cache manager
+ * @arg mngr		Cache manager.
+ * @arg cache		Cache to be added to cache manager
+ * @arg cb		V2 function to be called upon changes.
+ * @arg data		Argument passed on to change callback
+ *
+ * Adds cache to the manager. The operation will trigger a full
+ * dump request from the kernel to initially fill the contents
+ * of the cache. The manager will subscribe to the notification group
+ * of the cache and keep track of any further changes.
+ *
+ * The user is responsible for calling nl_cache_mngr_poll() or monitor
+ * the socket and call nl_cache_mngr_data_ready() to allow the library
+ * to process netlink notification events.
+ *
+ * @see nl_cache_mngr_poll()
+ * @see nl_cache_mngr_data_ready()
+ *
+ * @return 0 on success or a negative error code.
+ * @return -NLE_PROTO_MISMATCH Protocol mismatch between cache manager and
+ * 			       cache type
+ * @return -NLE_OPNOTSUPP Cache type does not support updates
+ * @return -NLE_EXIST Cache of this type already being managed
+ */
+int nl_cache_mngr_add_cache_v2(struct nl_cache_mngr *mngr, struct nl_cache *cache,
+		      change_func_v2_t cb, void *data) {
+	int err;
+	err = nl_cache_mngr_add_cache(mngr, cache, NULL, NULL);
+	if (err < 0)
+		return err;
+
+	return nl_cache_mngr_set_change_func_v2(mngr, cache, cb, data);
+}
+
 /**
  * Add cache to cache manager
  * @arg mngr		Cache manager.

lib/xfrm/sa.c

@@ -918,7 +918,8 @@ int xfrmnl_sa_parse(struct nlmsghdr *n, struct xfrmnl_sa **result)
 }
 
 static int xfrm_sa_update_cache (struct nl_cache *cache, struct nl_object *obj,
-                                 change_func_t change_cb, void *data)
+                                 change_func_t change_cb, change_func_v2_t change_cb_v2,
+				 void *data)
 {
 	struct nl_object*       old_sa;
 	struct xfrmnl_sa*       sa = (struct xfrmnl_sa*)obj;
@@ -947,26 +948,39 @@ static int xfrm_sa_update_cache (struct nl_cache *cache, struct nl_object *obj,
 			 * cache and notify application of the expiry event. */
 			nl_cache_move (cache, obj);
 
-			if (old_sa == NULL && change_cb)
+			if (old_sa == NULL)
 			{
 				/* Application CB present, no previous instance of SA object present.
 				 * Notify application CB as a NEW event */
-				change_cb (cache, obj, NL_ACT_NEW, data);
+				if (change_cb_v2)
+					change_cb_v2(cache, NULL, obj, 0, NL_ACT_NEW, data);
+				else if (change_cb)
+					change_cb(cache, obj, NL_ACT_NEW, data);
 			}
 			else if (old_sa)
 			{
+				uint64_t diff = 0;
+				if (change_cb || change_cb_v2)
+					diff = nl_object_diff64(old_sa, obj);
+
 				/* Application CB present, a previous instance of SA object present.
 				 * Notify application CB as a CHANGE1 event */
-				if (nl_object_diff (old_sa, obj) && change_cb)
-					change_cb (cache, obj, NL_ACT_CHANGE, data);
+				if (diff) {
+					if (change_cb_v2) {
+						change_cb_v2(cache, old_sa, obj, diff, NL_ACT_CHANGE, data);
+					} else if (change_cb)
+						change_cb(cache, obj, NL_ACT_CHANGE, data);
+				}
 				nl_object_put (old_sa);
 			}
 		}
 		else
 		{
 			/* Hard expiry event: Delete the object from the
 			 * cache and notify application of the expiry event. */
-			if (change_cb)
+			if (change_cb_v2)
+				change_cb_v2(cache, obj, NULL, 0, NL_ACT_DEL, data);
+			else if (change_cb)
 				change_cb (cache, obj, NL_ACT_DEL, data);
 			nl_object_put (old_sa);
 		}
@@ -978,7 +992,10 @@ static int xfrm_sa_update_cache (struct nl_cache *cache, struct nl_object *obj,
 	{
 		/* All other messages other than Expire, let the standard Libnl cache
 		 * module handle it. */
-		return nl_cache_include (cache, obj, change_cb, data);
+		if (change_cb_v2)
+			return nl_cache_include_v2(cache, obj, change_cb_v2, data);
+		else
+			return nl_cache_include (cache, obj, change_cb, data);
 	}
 }
 

libnl-3.sym

@@ -354,5 +354,7 @@ global:
 
 libnl_3_2_29 {
 global:
+	nl_cache_include_v2;
+	nl_cache_mngr_add_cache_v2;
 	nl_strerror_l;
 } libnl_3_2_28;