batman-adv: add reference counting for type batadv_tt_orig_list_entry

The batadv_tt_orig_list_entry structure didn't have any refcounting mechanism so far. This patch introduces it and makes the structure being usable in much more complex context. Signed-off-by: Antonio Quartulli <ordex@autistici.org>

batman-adv: add reference counting for type batadv_tt_orig_list_entry
The batadv_tt_orig_list_entry structure didn't have any refcounting mechanism so far. This patch introduces it and makes the structure being usable in much more complex context. Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Antonio Quartulli
1 parent 3a7f291bf6
Showing 2 changed files with 53 additions and 23 deletions Side-by-side Diff
net/batman-adv/translation-table.c
net/batman-adv/types.h
@@ -152,6 +152,8 @@
 static void
 batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
 {
+	if (!atomic_dec_and_test(&orig_entry->refcount))
+		return;
 	/* to avoid race conditions, immediately decrease the tt counter */
 	atomic_dec(&orig_entry->orig_node->tt_size);
 	call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
  
  
  
  
  
  
  
  
  
  
  
@@ -625,50 +627,82 @@
 	spin_unlock_bh(&bat_priv->tt_changes_list_lock);
 }
  
-/* find out if an orig_node is already in the list of a tt_global_entry.
- * returns 1 if found, 0 otherwise
+/* retrieves the orig_tt_list_entry belonging to orig_node from the
+ * batadv_tt_global_entry list
+ *
+ * returns it with an increased refcounter, NULL if not found
  */
-static bool
-batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
-				const struct batadv_orig_node *orig_node)
+static struct batadv_tt_orig_list_entry *
+batadv_tt_global_orig_entry_find(const struct batadv_tt_global_entry *entry,
+				 const struct batadv_orig_node *orig_node)
 {
-	struct batadv_tt_orig_list_entry *tmp_orig_entry;
+	struct batadv_tt_orig_list_entry *tmp_orig_entry, *orig_entry = NULL;
 	const struct hlist_head *head;
 	struct hlist_node *node;
-	bool found = false;
  
 	rcu_read_lock();
 	head = &entry->orig_list;
 	hlist_for_each_entry_rcu(tmp_orig_entry, node, head, list) {
-		if (tmp_orig_entry->orig_node == orig_node) {
-			found = true;
-			break;
-		}
+		if (tmp_orig_entry->orig_node != orig_node)
+			continue;
+		if (!atomic_inc_not_zero(&tmp_orig_entry->refcount))
+			continue;
+
+		orig_entry = tmp_orig_entry;
+		break;
 	}
 	rcu_read_unlock();
+
+	return orig_entry;
+}
+
+/* find out if an orig_node is already in the list of a tt_global_entry.
+ * returns true if found, false otherwise
+ */
+static bool
+batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
+				const struct batadv_orig_node *orig_node)
+{
+	struct batadv_tt_orig_list_entry *orig_entry;
+	bool found = false;
+
+	orig_entry = batadv_tt_global_orig_entry_find(entry, orig_node);
+	if (orig_entry) {
+		found = true;
+		batadv_tt_orig_list_entry_free_ref(orig_entry);
+	}
+
 	return found;
 }
  
 static void
-batadv_tt_global_add_orig_entry(struct batadv_tt_global_entry *tt_global_entry,
+batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global,
 				struct batadv_orig_node *orig_node, int ttvn)
 {
 	struct batadv_tt_orig_list_entry *orig_entry;
  
+	orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node);
+	if (orig_entry)
+		goto out;
+
 	orig_entry = kzalloc(sizeof(*orig_entry), GFP_ATOMIC);
 	if (!orig_entry)
-		return;
+		goto out;
  
 	INIT_HLIST_NODE(&orig_entry->list);
 	atomic_inc(&orig_node->refcount);
 	atomic_inc(&orig_node->tt_size);
 	orig_entry->orig_node = orig_node;
 	orig_entry->ttvn = ttvn;
+	atomic_set(&orig_entry->refcount, 2);
  
-	spin_lock_bh(&tt_global_entry->list_lock);
+	spin_lock_bh(&tt_global->list_lock);
 	hlist_add_head_rcu(&orig_entry->list,
-			   &tt_global_entry->orig_list);
-	spin_unlock_bh(&tt_global_entry->list_lock);
+			   &tt_global->orig_list);
+	spin_unlock_bh(&tt_global->list_lock);
+out:
+	if (orig_entry)
+		batadv_tt_orig_list_entry_free_ref(orig_entry);
 }
  
 /* caller must hold orig_node refcount */
@@ -709,9 +743,6 @@
 			batadv_tt_global_entry_free_ref(tt_global_entry);
 			goto out_remove;
 		}
-
-		batadv_tt_global_add_orig_entry(tt_global_entry, orig_node,
-						ttvn);
 	} else {
 		/* there is already a global entry, use this one. */
  
  
@@ -728,11 +759,9 @@
 			tt_global_entry->roam_at = 0;
 		}
  
-		if (!batadv_tt_global_entry_has_orig(tt_global_entry,
-						     orig_node))
-			batadv_tt_global_add_orig_entry(tt_global_entry,
-							orig_node, ttvn);
 	}
+	/* add the new orig_entry (if needed) */
+	batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);
  
 	batadv_dbg(BATADV_DBG_TT, bat_priv,
 		   "Creating new global tt entry: %pM (via %pM)\n",
@@ -282,6 +282,7 @@
 struct batadv_tt_orig_list_entry {
 	struct batadv_orig_node *orig_node;
 	uint8_t ttvn;
+	atomic_t refcount;
 	struct rcu_head rcu;
 	struct hlist_node list;
 };
...	...	@@ -152,6 +152,8 @@
152	152	static void
153	153	batadv_tt_orig_list_entry_free_ref(struct batadv_tt_orig_list_entry *orig_entry)
154	154	{
	155	+ if (!atomic_dec_and_test(&orig_entry->refcount))
	156	+ return;
155	157	/* to avoid race conditions, immediately decrease the tt counter */
156	158	atomic_dec(&orig_entry->orig_node->tt_size);
157	159	call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
158	160
159	161
160	162
161	163
162	164
163	165
164	166
165	167
166	168
167	169
168	170
...	...	@@ -625,50 +627,82 @@
625	627	spin_unlock_bh(&bat_priv->tt_changes_list_lock);
626	628	}
627	629
628		-/* find out if an orig_node is already in the list of a tt_global_entry.
629		- * returns 1 if found, 0 otherwise
	630	+/* retrieves the orig_tt_list_entry belonging to orig_node from the
	631	+ * batadv_tt_global_entry list
	632	+ *
	633	+ * returns it with an increased refcounter, NULL if not found
630	634	*/
631		-static bool
632		-batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
633		- const struct batadv_orig_node *orig_node)
	635	+static struct batadv_tt_orig_list_entry *
	636	+batadv_tt_global_orig_entry_find(const struct batadv_tt_global_entry *entry,
	637	+ const struct batadv_orig_node *orig_node)
634	638	{
635		- struct batadv_tt_orig_list_entry *tmp_orig_entry;
	639	+ struct batadv_tt_orig_list_entry tmp_orig_entry, orig_entry = NULL;
636	640	const struct hlist_head *head;
637	641	struct hlist_node *node;
638		- bool found = false;
639	642
640	643	rcu_read_lock();
641	644	head = &entry->orig_list;
642	645	hlist_for_each_entry_rcu(tmp_orig_entry, node, head, list) {
643		- if (tmp_orig_entry->orig_node == orig_node) {
644		- found = true;
645		- break;
646		- }
	646	+ if (tmp_orig_entry->orig_node != orig_node)
	647	+ continue;
	648	+ if (!atomic_inc_not_zero(&tmp_orig_entry->refcount))
	649	+ continue;
	650	+
	651	+ orig_entry = tmp_orig_entry;
	652	+ break;
647	653	}
648	654	rcu_read_unlock();
	655	+
	656	+ return orig_entry;
	657	+}
	658	+
	659	+/* find out if an orig_node is already in the list of a tt_global_entry.
	660	+ * returns true if found, false otherwise
	661	+ */
	662	+static bool
	663	+batadv_tt_global_entry_has_orig(const struct batadv_tt_global_entry *entry,
	664	+ const struct batadv_orig_node *orig_node)
	665	+{
	666	+ struct batadv_tt_orig_list_entry *orig_entry;
	667	+ bool found = false;
	668	+
	669	+ orig_entry = batadv_tt_global_orig_entry_find(entry, orig_node);
	670	+ if (orig_entry) {
	671	+ found = true;
	672	+ batadv_tt_orig_list_entry_free_ref(orig_entry);
	673	+ }
	674	+
649	675	return found;
650	676	}
651	677
652	678	static void
653		-batadv_tt_global_add_orig_entry(struct batadv_tt_global_entry *tt_global_entry,
	679	+batadv_tt_global_orig_entry_add(struct batadv_tt_global_entry *tt_global,
654	680	struct batadv_orig_node *orig_node, int ttvn)
655	681	{
656	682	struct batadv_tt_orig_list_entry *orig_entry;
657	683
	684	+ orig_entry = batadv_tt_global_orig_entry_find(tt_global, orig_node);
	685	+ if (orig_entry)
	686	+ goto out;
	687	+
658	688	orig_entry = kzalloc(sizeof(*orig_entry), GFP_ATOMIC);
659	689	if (!orig_entry)
660		- return;
	690	+ goto out;
661	691
662	692	INIT_HLIST_NODE(&orig_entry->list);
663	693	atomic_inc(&orig_node->refcount);
664	694	atomic_inc(&orig_node->tt_size);
665	695	orig_entry->orig_node = orig_node;
666	696	orig_entry->ttvn = ttvn;
	697	+ atomic_set(&orig_entry->refcount, 2);
667	698
668		- spin_lock_bh(&tt_global_entry->list_lock);
	699	+ spin_lock_bh(&tt_global->list_lock);
669	700	hlist_add_head_rcu(&orig_entry->list,
670		- &tt_global_entry->orig_list);
671		- spin_unlock_bh(&tt_global_entry->list_lock);
	701	+ &tt_global->orig_list);
	702	+ spin_unlock_bh(&tt_global->list_lock);
	703	+out:
	704	+ if (orig_entry)
	705	+ batadv_tt_orig_list_entry_free_ref(orig_entry);
672	706	}
673	707
674	708	/* caller must hold orig_node refcount */
...	...	@@ -709,9 +743,6 @@
709	743	batadv_tt_global_entry_free_ref(tt_global_entry);
710	744	goto out_remove;
711	745	}
712		-
713		- batadv_tt_global_add_orig_entry(tt_global_entry, orig_node,
714		- ttvn);
715	746	} else {
716	747	/* there is already a global entry, use this one. */
717	748
718	749
...	...	@@ -728,11 +759,9 @@
728	759	tt_global_entry->roam_at = 0;
729	760	}
730	761
731		- if (!batadv_tt_global_entry_has_orig(tt_global_entry,
732		- orig_node))
733		- batadv_tt_global_add_orig_entry(tt_global_entry,
734		- orig_node, ttvn);
735	762	}
	763	+ /* add the new orig_entry (if needed) */
	764	+ batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);
736	765
737	766	batadv_dbg(BATADV_DBG_TT, bat_priv,
738	767	"Creating new global tt entry: %pM (via %pM)\n",
...	...	@@ -282,6 +282,7 @@
282	282	struct batadv_tt_orig_list_entry {
283	283	struct batadv_orig_node *orig_node;
284	284	uint8_t ttvn;
	285	+ atomic_t refcount;
285	286	struct rcu_head rcu;
286	287	struct hlist_node list;
287	288	};