[B.A.T.M.A.N.] [PATCH v4 26/31] batman-adv: Convert batadv_neigh_node to kref

Sven Eckelmann
2016-01-05T11:06:41Z

batman-adv uses a self-written reference implementation which is just based
on atomic_t. This is less obvious when reading the code than kref and
therefore increases the change that the reference counting will be missed.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
v4:
- fix function names in commit messages
- fix double whitespace in batadv_tt_orig_list_entry_release kerneldoc
- add extra patch for batadv_claim_free_ref kerneldoc fix
- change the phrase "free it" in all *_free_ref/*_put functions to "release it"
v3:
- update copyright year
v2:
- split patchset into fixes and kref migration to make it easier when the
decision is made where each patch will be applied

net/batman-adv/bat_iv_ogm.c | 5 +++--
net/batman-adv/originator.c | 22 ++++++++++++----------
net/batman-adv/routing.c | 8 ++++----
net/batman-adv/types.h | 2 +-
4 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 12bdffa..895e697 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -31,6 +31,7 @@
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/list.h>
+#include <linux/kref.h>
#include <linux/netdevice.h>
#include <linux/pkt_sched.h>
#include <linux/printk.h>
@@ -1000,7 +1001,7 @@ batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
neigh_addr = tmp_neigh_node->addr;
if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
tmp_neigh_node->if_incoming == if_incoming &&
- atomic_inc_not_zero(&tmp_neigh_node->refcount)) {
+ kref_get_unless_zero(&tmp_neigh_node->refcount)) {
if (WARN(neigh_node, "too many matching neigh_nodes"))
batadv_neigh_node_free_ref(neigh_node);
neigh_node = tmp_neigh_node;
@@ -1159,7 +1160,7 @@ static int batadv_iv_ogm_calc_tq(struct batadv_orig_node *orig_node,
if (tmp_neigh_node->if_incoming != if_incoming)
continue;

- if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
+ if (!kref_get_unless_zero(&tmp_neigh_node->refcount))
continue;

neigh_node = tmp_neigh_node;
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 4874526..e615174 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -229,15 +229,17 @@ void batadv_hardif_neigh_free_ref(struct batadv_hardif_neigh_node *hardif_neigh)
/**
* batadv_neigh_node_release - release neigh_node from lists and queue for
* free after rcu grace period
- * @neigh_node: neigh neighbor to free
+ * @ref: kref pointer of the neigh_node
*/
-static void batadv_neigh_node_release(struct batadv_neigh_node *neigh_node)
+static void batadv_neigh_node_release(struct kref *ref)
{
struct hlist_node *node_tmp;
+ struct batadv_neigh_node *neigh_node;
struct batadv_hardif_neigh_node *hardif_neigh;
struct batadv_neigh_ifinfo *neigh_ifinfo;
struct batadv_algo_ops *bao;

+ neigh_node = container_of(ref, struct batadv_neigh_node, refcount);
bao = neigh_node->orig_node->bat_priv->bat_algo_ops;

hlist_for_each_entry_safe(neigh_ifinfo, node_tmp,
@@ -262,14 +264,13 @@ static void batadv_neigh_node_release(struct batadv_neigh_node *neigh_node)
}

/**
- * batadv_neigh_node_free_ref - decrement the neighbors refcounter
- * and possibly release it
+ * batadv_neigh_node_free_ref - decrement the neighbors refcounter and possibly
+ * release it
* @neigh_node: neigh neighbor to free
*/
void batadv_neigh_node_free_ref(struct batadv_neigh_node *neigh_node)
{
- if (atomic_dec_and_test(&neigh_node->refcount))
- batadv_neigh_node_release(neigh_node);
+ kref_put(&neigh_node->refcount, batadv_neigh_node_release);
}

/**
@@ -298,7 +299,7 @@ batadv_orig_router_get(struct batadv_orig_node *orig_node,
break;
}

- if (router && !atomic_inc_not_zero(&router->refcount))
+ if (router && !kref_get_unless_zero(&router->refcount))
router = NULL;

rcu_read_unlock();
@@ -491,7 +492,7 @@ batadv_neigh_node_get(const struct batadv_orig_node *orig_node,
if (tmp_neigh_node->if_incoming != hard_iface)
continue;

- if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
+ if (!kref_get_unless_zero(&tmp_neigh_node->refcount))
continue;

res = tmp_neigh_node;
@@ -649,7 +650,8 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node,
neigh_node->orig_node = orig_node;

/* extra reference for return */
- atomic_set(&neigh_node->refcount, 2);
+ kref_init(&neigh_node->refcount);
+ kref_get(&neigh_node->refcount);

spin_lock_bh(&orig_node->neigh_list_lock);
hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
@@ -1084,7 +1086,7 @@ batadv_find_best_neighbor(struct batadv_priv *bat_priv,
best, if_outgoing) <= 0))
continue;

- if (!atomic_inc_not_zero(&neigh->refcount))
+ if (!kref_get_unless_zero(&neigh->refcount))
continue;

if (best)
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 99fd1df..f2410ba 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -73,7 +73,7 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,

rcu_read_lock();
curr_router = rcu_dereference(orig_ifinfo->router);
- if (curr_router && !atomic_inc_not_zero(&curr_router->refcount))
+ if (curr_router && !kref_get_unless_zero(&curr_router->refcount))
curr_router = NULL;
rcu_read_unlock();

@@ -101,7 +101,7 @@ static void _batadv_update_route(struct batadv_priv *bat_priv,
batadv_neigh_node_free_ref(curr_router);

/* increase refcount of new best neighbor */
- if (neigh_node && !atomic_inc_not_zero(&neigh_node->refcount))
+ if (neigh_node && !kref_get_unless_zero(&neigh_node->refcount))
neigh_node = NULL;

spin_lock_bh(&orig_node->neigh_list_lock);
@@ -505,7 +505,7 @@ batadv_find_router(struct batadv_priv *bat_priv,
if (!cand_router)
goto next;

- if (!atomic_inc_not_zero(&cand_router->refcount)) {
+ if (!kref_get_unless_zero(&cand_router->refcount)) {
cand_router = NULL;
goto next;
}
@@ -524,7 +524,7 @@ batadv_find_router(struct batadv_priv *bat_priv,

/* mark the first possible candidate */
if (!first_candidate) {
- atomic_inc(&cand_router->refcount);
+ kref_get(&cand_router->refcount);
kref_get(&cand->refcount);
first_candidate = cand;
first_candidate_router = cand_router;
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index a5e4310..75e1b45 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -384,7 +384,7 @@ struct batadv_neigh_node {
spinlock_t ifinfo_lock; /* protects ifinfo_list and its members */
struct batadv_hard_iface *if_incoming;
unsigned long last_seen;
- atomic_t refcount;
+ struct kref refcount;
struct rcu_head rcu;
};

--
2.6.4