[B.A.T.M.A.N.] [PATCH v4 22/31] batman-adv: Convert batadv_tvlv_handler to kref

Sven Eckelmann
2016-01-05T11:06:37Z

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/main.c | 24 ++++++++++++++++++------
net/batman-adv/types.h | 2 +-
2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 476890e..2777372 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -625,15 +625,27 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr)
}

/**
- * batadv_tvlv_handler_free_ref - decrement the tvlv handler refcounter and
- * possibly free it
+ * batadv_tvlv_handler_release - release tvlv handler from lists and queue for
+ * free after rcu grace period
+ * @ref: kref pointer of the tvlv
+ */
+static void batadv_tvlv_handler_release(struct kref *ref)
+{
+ struct batadv_tvlv_handler *tvlv_handler;
+
+ tvlv_handler = container_of(ref, struct batadv_tvlv_handler, refcount);
+ kfree_rcu(tvlv_handler, rcu);
+}
+
+/**
+ * batadv_tvlv_handler_free_ref - decrement the tvlv container refcounter and
+ * possibly release it
* @tvlv_handler: the tvlv handler to free
*/
static void
batadv_tvlv_handler_free_ref(struct batadv_tvlv_handler *tvlv_handler)
{
- if (atomic_dec_and_test(&tvlv_handler->refcount))
- kfree_rcu(tvlv_handler, rcu);
+ kref_put(&tvlv_handler->refcount, batadv_tvlv_handler_release);
}

/**
@@ -659,7 +671,7 @@ static struct batadv_tvlv_handler
if (tvlv_handler_tmp->version != version)
continue;

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

tvlv_handler = tvlv_handler_tmp;
@@ -1108,7 +1120,7 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv,
tvlv_handler->type = type;
tvlv_handler->version = version;
tvlv_handler->flags = flags;
- atomic_set(&tvlv_handler->refcount, 1);
+ kref_init(&tvlv_handler->refcount);
INIT_HLIST_NODE(&tvlv_handler->list);

spin_lock_bh(&bat_priv->tvlv.handler_list_lock);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 0ebd5a4..60d304b 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1293,7 +1293,7 @@ struct batadv_tvlv_handler {
u8 type;
u8 version;
u8 flags;
- atomic_t refcount;
+ struct kref refcount;
struct rcu_head rcu;
};

--
2.6.4