The callers of the functions using batadv_hard_iface objects have to make sure that they already hold a valid reference. The subfunctions don't have to check whether the reference counter is > 0 because this was already checked by the callers.
The kref_get function instead WARNs (with debug information) when the reference counter would still be 0. This makes a bug in batman-adv better visible because kref_get_unless_zero would have ignored this problem. Signed-off-by: Sven Eckelmann <[email protected]> --- Andrew, this should be what you've reported in https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2016-March/014588.html and what I've added to the issue tracker at https://www.open-mesh.org/issues/244 net/batman-adv/bat_iv_ogm.c | 9 ++------- net/batman-adv/hard-interface.c | 7 +++---- net/batman-adv/originator.c | 30 +++++++----------------------- 3 files changed, 12 insertions(+), 34 deletions(-) diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index b390ff9..d389dc6 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -679,12 +679,6 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff, unsigned char *skb_buff; unsigned int skb_size; - if (!kref_get_unless_zero(&if_incoming->refcount)) - return; - - if (!kref_get_unless_zero(&if_outgoing->refcount)) - goto out_free_incoming; - /* own packet should always be scheduled */ if (!own_packet) { if (!batadv_atomic_dec_not_zero(&bat_priv->batman_queue_left)) { @@ -716,6 +710,8 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff, forw_packet_aggr->packet_len = packet_len; memcpy(skb_buff, packet_buff, packet_len); + kref_get(&if_incoming->refcount); + kref_get(&if_outgoing->refcount); forw_packet_aggr->own = own_packet; forw_packet_aggr->if_incoming = if_incoming; forw_packet_aggr->if_outgoing = if_outgoing; @@ -747,7 +743,6 @@ out_nomem: atomic_inc(&bat_priv->batman_queue_left); out_free_outgoing: batadv_hardif_put(if_outgoing); -out_free_incoming: batadv_hardif_put(if_incoming); } diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index 56b148a..e70d13f 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -236,8 +236,8 @@ static void batadv_primary_if_select(struct batadv_priv *bat_priv, ASSERT_RTNL(); - if (new_hard_iface && !kref_get_unless_zero(&new_hard_iface->refcount)) - new_hard_iface = NULL; + if (new_hard_iface) + kref_get(&new_hard_iface->refcount); curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1); rcu_assign_pointer(bat_priv->primary_if, new_hard_iface); @@ -464,8 +464,7 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface, if (hard_iface->if_status != BATADV_IF_NOT_IN_USE) goto out; - if (!kref_get_unless_zero(&hard_iface->refcount)) - goto out; + kref_get(&hard_iface->refcount); soft_iface = dev_get_by_name(&init_net, iface_name); diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c index 44c508a..2d288ea 100644 --- a/net/batman-adv/originator.c +++ b/net/batman-adv/originator.c @@ -381,12 +381,8 @@ batadv_orig_ifinfo_new(struct batadv_orig_node *orig_node, if (!orig_ifinfo) goto out; - if (if_outgoing != BATADV_IF_DEFAULT && - !kref_get_unless_zero(&if_outgoing->refcount)) { - kfree(orig_ifinfo); - orig_ifinfo = NULL; - goto out; - } + if (if_outgoing != BATADV_IF_DEFAULT) + kref_get(&if_outgoing->refcount); reset_time = jiffies - 1; reset_time -= msecs_to_jiffies(BATADV_RESET_PROTECTION_MS); @@ -462,11 +458,8 @@ batadv_neigh_ifinfo_new(struct batadv_neigh_node *neigh, if (!neigh_ifinfo) goto out; - if (if_outgoing && !kref_get_unless_zero(&if_outgoing->refcount)) { - kfree(neigh_ifinfo); - neigh_ifinfo = NULL; - goto out; - } + if (if_outgoing) + kref_get(&if_outgoing->refcount); INIT_HLIST_NODE(&neigh_ifinfo->list); kref_init(&neigh_ifinfo->refcount); @@ -539,15 +532,11 @@ batadv_hardif_neigh_create(struct batadv_hard_iface *hard_iface, if (hardif_neigh) goto out; - if (!kref_get_unless_zero(&hard_iface->refcount)) - goto out; - hardif_neigh = kzalloc(sizeof(*hardif_neigh), GFP_ATOMIC); - if (!hardif_neigh) { - batadv_hardif_put(hard_iface); + if (!hardif_neigh) goto out; - } + kref_get(&hard_iface->refcount); INIT_HLIST_NODE(&hardif_neigh->list); ether_addr_copy(hardif_neigh->addr, neigh_addr); hardif_neigh->if_incoming = hard_iface; @@ -650,16 +639,11 @@ batadv_neigh_node_new(struct batadv_orig_node *orig_node, if (!neigh_node) goto out; - if (!kref_get_unless_zero(&hard_iface->refcount)) { - kfree(neigh_node); - neigh_node = NULL; - goto out; - } - INIT_HLIST_NODE(&neigh_node->list); INIT_HLIST_HEAD(&neigh_node->ifinfo_list); spin_lock_init(&neigh_node->ifinfo_lock); + kref_get(&hard_iface->refcount); ether_addr_copy(neigh_node->addr, neigh_addr); neigh_node->if_incoming = hard_iface; neigh_node->orig_node = orig_node; -- 2.7.0
