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/gateway_client.c | 40 +++++++++++++++++++++++++++++----------- net/batman-adv/types.h | 2 +- 2 files changed, 30 insertions(+), 12 deletions(-)
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 8350775..bf5a6ef 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -28,6 +28,7 @@ #include <linux/ip.h> #include <linux/ipv6.h> #include <linux/kernel.h> +#include <linux/kref.h> #include <linux/list.h> #include <linux/netdevice.h> #include <linux/rculist.h> @@ -59,12 +60,29 @@ */ #define BATADV_DHCP_CHADDR_OFFSET 28
+/** + * batadv_gw_node_release - release gw_node from lists and queue for free after + * rcu grace period + * @ref: kref pointer of the gw_node + */ +static void batadv_gw_node_release(struct kref *ref) +{ + struct batadv_gw_node *gw_node; + + gw_node = container_of(ref, struct batadv_gw_node, refcount); + + batadv_orig_node_free_ref(gw_node->orig_node); + kfree_rcu(gw_node, rcu); +} + +/** + * batadv_gw_node_free_ref - decrement the gw_node refcounter and possibly + * release it + * @gw_node: gateway node to free + */ static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node) { - if (atomic_dec_and_test(&gw_node->refcount)) { - batadv_orig_node_free_ref(gw_node->orig_node); - kfree_rcu(gw_node, rcu); - } + kref_put(&gw_node->refcount, batadv_gw_node_release); }
static struct batadv_gw_node * @@ -77,7 +95,7 @@ batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) if (!gw_node) goto out;
- if (!atomic_inc_not_zero(&gw_node->refcount)) + if (!kref_get_unless_zero(&gw_node->refcount)) gw_node = NULL;
out: @@ -118,7 +136,7 @@ static void batadv_gw_select(struct batadv_priv *bat_priv,
spin_lock_bh(&bat_priv->gw.list_lock);
- if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount)) + if (new_gw_node && !kref_get_unless_zero(&new_gw_node->refcount)) new_gw_node = NULL;
curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1); @@ -170,7 +188,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) if (!router_ifinfo) goto next;
- if (!atomic_inc_not_zero(&gw_node->refcount)) + if (!kref_get_unless_zero(&gw_node->refcount)) goto next;
tq_avg = router_ifinfo->bat_iv.tq_avg; @@ -188,7 +206,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) if (curr_gw) batadv_gw_node_free_ref(curr_gw); curr_gw = gw_node; - atomic_inc(&curr_gw->refcount); + kref_get(&curr_gw->refcount); } break;
@@ -203,7 +221,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) if (curr_gw) batadv_gw_node_free_ref(curr_gw); curr_gw = gw_node; - atomic_inc(&curr_gw->refcount); + kref_get(&curr_gw->refcount); } break; } @@ -436,7 +454,7 @@ static void batadv_gw_node_add(struct batadv_priv *bat_priv, gw_node->orig_node = orig_node; gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); - atomic_set(&gw_node->refcount, 1); + kref_init(&gw_node->refcount);
spin_lock_bh(&bat_priv->gw.list_lock); hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list); @@ -469,7 +487,7 @@ batadv_gw_node_get(struct batadv_priv *bat_priv, if (gw_node_tmp->orig_node != orig_node) continue;
- if (!atomic_inc_not_zero(&gw_node_tmp->refcount)) + if (!kref_get_unless_zero(&gw_node_tmp->refcount)) continue;
gw_node = gw_node_tmp; diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 091ad76..0b3cbdb 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -342,7 +342,7 @@ struct batadv_gw_node { struct batadv_orig_node *orig_node; u32 bandwidth_down; u32 bandwidth_up; - atomic_t refcount; + struct kref refcount; struct rcu_head rcu; };