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batman-adv: add reference counting for type batadv_tt_orig_list_entry

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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>
This commit is contained in:
Antonio Quartulli 2012-07-01 14:09:12 +02:00
parent 3a7f291bf6
commit d657e621a0
2 changed files with 54 additions and 24 deletions
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77
net/batman-adv/translation-table.c
View File

@ -152,6 +152,8 @@ static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
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 @@ static void batadv_tt_changes_list_free(struct batadv_priv *bat_priv)
spin_unlock_bh(&bat_priv->tt_changes_list_lock);
}
/* 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 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, *orig_entry = NULL;
const struct hlist_head *head;
struct hlist_node *node;
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)
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 1 if found, 0 otherwise
* 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 *tmp_orig_entry;
const struct hlist_head *head;
struct hlist_node *node;
struct batadv_tt_orig_list_entry *orig_entry;
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;
}
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);
}
rcu_read_unlock();
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 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
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 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
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",

1
net/batman-adv/types.h
View File

@ -282,6 +282,7 @@ struct batadv_tt_global_entry {
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;
};