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 --- v6: - removed patches which are now applied in the branch next - rebased remaining patches on the patch "batman-adv: Avoid recursive call_rcu for batadv_nc_node" which was modified by Marek while he applied the patches (this unfortunately made some of the remaining patches "hard" to apply) v5: - add hack which allows to compile against stable kernel like 3.2.44 which also added the kref_get_unless_zero function 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/bridge_loop_avoidance.c | 29 +++++++++++++++++++++++------ net/batman-adv/types.h | 2 +- 2 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 7e92fd1..0937097 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -31,6 +31,7 @@ #include <linux/jhash.h> #include <linux/jiffies.h> #include <linux/kernel.h> +#include <linux/kref.h> #include <linux/list.h> #include <linux/lockdep.h> #include <linux/netdevice.h> @@ -143,14 +144,29 @@ static int batadv_compare_claim(const struct hlist_node *node, }
/** - * batadv_compare_backbone_gw - free backbone gw + * batadv_backbone_gw_release - release backbone gw from lists and queue for + * free after rcu grace period + * @ref: kref pointer of the backbone gw + */ +static void batadv_backbone_gw_release(struct kref *ref) +{ + struct batadv_bla_backbone_gw *backbone_gw; + + backbone_gw = container_of(ref, struct batadv_bla_backbone_gw, + refcount); + + kfree_rcu(backbone_gw, rcu); +} + +/** + * batadv_backbone_gw_free_ref - decrement the backbone gw refcounter and + * possibly release it * @backbone_gw: backbone gateway to be free'd */ static void batadv_backbone_gw_free_ref(struct batadv_bla_backbone_gw *backbone_gw) { - if (atomic_dec_and_test(&backbone_gw->refcount)) - kfree_rcu(backbone_gw, rcu); + kref_put(&backbone_gw->refcount, batadv_backbone_gw_release); }
/** @@ -247,7 +263,7 @@ batadv_backbone_hash_find(struct batadv_priv *bat_priv, u8 *addr, &search_entry)) continue;
- if (!atomic_inc_not_zero(&backbone_gw->refcount)) + if (!kref_get_unless_zero(&backbone_gw->refcount)) continue;
backbone_gw_tmp = backbone_gw; @@ -448,7 +464,8 @@ batadv_bla_get_backbone_gw(struct batadv_priv *bat_priv, u8 *orig, ether_addr_copy(entry->orig, orig);
/* one for the hash, one for returning */ - atomic_set(&entry->refcount, 2); + kref_init(&entry->refcount); + kref_get(&entry->refcount);
hash_added = batadv_hash_add(bat_priv->bla.backbone_hash, batadv_compare_backbone_gw, @@ -664,7 +681,7 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, batadv_backbone_gw_free_ref(claim->backbone_gw); } /* set (new) backbone gw */ - atomic_inc(&backbone_gw->refcount); + kref_get(&backbone_gw->refcount); claim->backbone_gw = backbone_gw;
spin_lock_bh(&backbone_gw->crc_lock); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 868f6b5..595f524 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -930,7 +930,7 @@ struct batadv_bla_backbone_gw { atomic_t request_sent; u16 crc; spinlock_t crc_lock; /* protects crc */ - atomic_t refcount; + struct kref refcount; struct rcu_head rcu; };