[B.A.T.M.A.N.] [PATCH 10/28] batman-adv: protect bonding with rcu locks

Sven Eckelmann
2011-03-05T12:28:24Z

From: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>

bonding / alternating candidates need to be secured by rcu locks
as well. This patch therefore converts the bonding list
from a plain pointer list to a rcu securable lists and references
the bonding candidates.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
---
net/batman-adv/hard-interface.c | 2 +-
net/batman-adv/originator.c | 25 +++-
net/batman-adv/originator.h | 1 +
net/batman-adv/routing.c | 313 ++++++++++++++++++++-------------------
net/batman-adv/routing.h | 6 +-
net/batman-adv/types.h | 9 +-
net/batman-adv/unicast.c | 2 +-
7 files changed, 195 insertions(+), 163 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index f2131f4..e2b001a 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -271,7 +271,7 @@ static void hardif_activate_interface(struct batman_if *batman_if)
static void hardif_deactivate_interface(struct batman_if *batman_if)
{
if ((batman_if->if_status != IF_ACTIVE) &&
- (batman_if->if_status != IF_TO_BE_ACTIVATED))
+ (batman_if->if_status != IF_TO_BE_ACTIVATED))
return;

batman_if->if_status = IF_INACTIVE;
diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 71dfc24..a85eadc 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -75,6 +75,14 @@ static void neigh_node_free_rcu(struct rcu_head *rcu)
kref_put(&neigh_node->refcount, neigh_node_free_ref);
}

+void neigh_node_free_rcu_bond(struct rcu_head *rcu)
+{
+ struct neigh_node *neigh_node;
+
+ neigh_node = container_of(rcu, struct neigh_node, rcu_bond);
+ kref_put(&neigh_node->refcount, neigh_node_free_ref);
+}
+
struct neigh_node *create_neighbor(struct orig_node *orig_node,
struct orig_node *orig_neigh_node,
uint8_t *neigh,
@@ -91,6 +99,7 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
return NULL;

INIT_HLIST_NODE(&neigh_node->list);
+ INIT_LIST_HEAD(&neigh_node->bonding_list);

memcpy(neigh_node->addr, neigh, ETH_ALEN);
neigh_node->orig_node = orig_neigh_node;
@@ -106,13 +115,20 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
void orig_node_free_ref(struct kref *refcount)
{
struct hlist_node *node, *node_tmp;
- struct neigh_node *neigh_node;
+ struct neigh_node *neigh_node, *tmp_neigh_node;
struct orig_node *orig_node;

orig_node = container_of(refcount, struct orig_node, refcount);

spin_lock_bh(&orig_node->neigh_list_lock);

+ /* for all bonding members ... */
+ list_for_each_entry_safe(neigh_node, tmp_neigh_node,
+ &orig_node->bond_list, bonding_list) {
+ list_del_rcu(&neigh_node->bonding_list);
+ call_rcu(&neigh_node->rcu_bond, neigh_node_free_rcu_bond);
+ }
+
/* for all neighbors towards this originator ... */
hlist_for_each_entry_safe(neigh_node, node, node_tmp,
&orig_node->neigh_list, list) {
@@ -207,6 +223,7 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
return NULL;

INIT_HLIST_HEAD(&orig_node->neigh_list);
+ INIT_LIST_HEAD(&orig_node->bond_list);
spin_lock_init(&orig_node->ogm_cnt_lock);
spin_lock_init(&orig_node->neigh_list_lock);
kref_init(&orig_node->refcount);
@@ -220,6 +237,8 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
orig_node->batman_seqno_reset = jiffies - 1
- msecs_to_jiffies(RESET_PROTECTION_MS);

+ atomic_set(&orig_node->bond_candidates, 0);
+
size = bat_priv->num_ifaces * sizeof(unsigned long) * NUM_WORDS;

orig_node->bcast_own = kzalloc(size, GFP_ATOMIC);
@@ -295,6 +314,7 @@ static bool purge_orig_neighbors(struct bat_priv *bat_priv,
neigh_purged = true;

hlist_del_rcu(&neigh_node->list);
+ bonding_candidate_del(orig_node, neigh_node);
call_rcu(&neigh_node->rcu, neigh_node_free_rcu);
} else {
if ((!*best_neigh_node) ||
@@ -326,9 +346,6 @@ static bool purge_orig_node(struct bat_priv *bat_priv,
best_neigh_node,
orig_node->hna_buff,
orig_node->hna_buff_len);
- /* update bonding candidates, we could have lost
- * some candidates. */
- update_bonding_candidates(orig_node);
}
}

diff --git a/net/batman-adv/originator.h b/net/batman-adv/originator.h
index edc64dc..360dfd1 100644
--- a/net/batman-adv/originator.h
+++ b/net/batman-adv/originator.h
@@ -26,6 +26,7 @@ int originator_init(struct bat_priv *bat_priv);
void originator_free(struct bat_priv *bat_priv);
void purge_orig_ref(struct bat_priv *bat_priv);
void orig_node_free_ref(struct kref *refcount);
+void neigh_node_free_rcu_bond(struct rcu_head *rcu);
struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr);
struct neigh_node *create_neighbor(struct orig_node *orig_node,
struct orig_node *orig_neigh_node,
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 7627ebe..1ad14da 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -271,6 +271,101 @@ out:
return ret;
}

+/* caller must hold the neigh_list_lock */
+void bonding_candidate_del(struct orig_node *orig_node,
+ struct neigh_node *neigh_node)
+{
+ /* this neighbor is not part of our candidate list */
+ if (list_empty(&neigh_node->bonding_list))
+ goto out;
+
+ list_del_rcu(&neigh_node->bonding_list);
+ call_rcu(&neigh_node->rcu_bond, neigh_node_free_rcu_bond);
+ INIT_LIST_HEAD(&neigh_node->bonding_list);
+ atomic_dec(&orig_node->bond_candidates);
+
+out:
+ return;
+}
+
+static void bonding_candidate_add(struct orig_node *orig_node,
+ struct neigh_node *neigh_node)
+{
+ struct hlist_node *node;
+ struct neigh_node *tmp_neigh_node;
+ uint8_t best_tq, interference_candidate = 0;
+
+ spin_lock_bh(&orig_node->neigh_list_lock);
+
+ /* only consider if it has the same primary address ... */
+ if (!compare_orig(orig_node->orig,
+ neigh_node->orig_node->primary_addr))
+ goto candidate_del;
+
+ if (!orig_node->router)
+ goto candidate_del;
+
+ best_tq = orig_node->router->tq_avg;
+
+ /* ... and is good enough to be considered */
+ if (neigh_node->tq_avg < best_tq - BONDING_TQ_THRESHOLD)
+ goto candidate_del;
+
+ /**
+ * check if we have another candidate with the same mac address or
+ * interface. If we do, we won't select this candidate because of
+ * possible interference.
+ */
+ hlist_for_each_entry_rcu(tmp_neigh_node, node,
+ &orig_node->neigh_list, list) {
+
+ if (tmp_neigh_node == neigh_node)
+ continue;
+
+ /* we only care if the other candidate is even
+ * considered as candidate. */
+ if (list_empty(&tmp_neigh_node->bonding_list))
+ continue;
+
+ if ((neigh_node->if_incoming == tmp_neigh_node->if_incoming) ||
+ (compare_orig(neigh_node->addr, tmp_neigh_node->addr))) {
+ interference_candidate = 1;
+ break;
+ }
+ }
+
+ /* don't care further if it is an interference candidate */
+ if (interference_candidate)
+ goto candidate_del;
+
+ /* this neighbor already is part of our candidate list */
+ if (!list_empty(&neigh_node->bonding_list))
+ goto out;
+
+ list_add_rcu(&neigh_node->bonding_list, &orig_node->bond_list);
+ kref_get(&neigh_node->refcount);
+ atomic_inc(&orig_node->bond_candidates);
+ goto out;
+
+candidate_del:
+ bonding_candidate_del(orig_node, neigh_node);
+
+out:
+ spin_unlock_bh(&orig_node->neigh_list_lock);
+ return;
+}
+
+/* copy primary address for bonding */
+static void bonding_save_primary(struct orig_node *orig_node,
+ struct orig_node *orig_neigh_node,
+ struct batman_packet *batman_packet)
+{
+ if (!(batman_packet->flags & PRIMARIES_FIRST_HOP))
+ return;
+
+ memcpy(orig_neigh_node->primary_addr, orig_node->orig, ETH_ALEN);
+}
+
static void update_orig(struct bat_priv *bat_priv,
struct orig_node *orig_node,
struct ethhdr *ethhdr,
@@ -339,6 +434,8 @@ static void update_orig(struct bat_priv *bat_priv,
neigh_node->last_ttl = batman_packet->ttl;
}

+ bonding_candidate_add(orig_node, neigh_node);
+
tmp_hna_buff_len = (hna_buff_len > batman_packet->num_hna * ETH_ALEN ?
batman_packet->num_hna * ETH_ALEN : hna_buff_len);

@@ -497,123 +594,10 @@ err:
return -1;
}

-/* copy primary address for bonding */
-static void mark_bonding_address(struct orig_node *orig_node,
- struct orig_node *orig_neigh_node,
- struct batman_packet *batman_packet)
-
-{
- if (batman_packet->flags & PRIMARIES_FIRST_HOP)
- memcpy(orig_neigh_node->primary_addr,
- orig_node->orig, ETH_ALEN);
-
- return;
-}
-
-/* mark possible bond.candidates in the neighbor list */
-void update_bonding_candidates(struct orig_node *orig_node)
-{
- int candidates;
- int interference_candidate;
- int best_tq;
- struct hlist_node *node, *node2;
- struct neigh_node *tmp_neigh_node, *tmp_neigh_node2;
- struct neigh_node *first_candidate, *last_candidate;
-
- /* update the candidates for this originator */
- if (!orig_node->router) {
- orig_node->bond.candidates = 0;
- return;
- }
-
- best_tq = orig_node->router->tq_avg;
-
- /* update bond.candidates */
-
- candidates = 0;
-
- /* mark other nodes which also received "PRIMARIES FIRST HOP" packets
- * as "bonding partner" */
-
- /* first, zero the list */
- rcu_read_lock();
- hlist_for_each_entry_rcu(tmp_neigh_node, node,
- &orig_node->neigh_list, list) {
- tmp_neigh_node->next_bond_candidate = NULL;
- }
- rcu_read_unlock();
-
- first_candidate = NULL;
- last_candidate = NULL;
-
- rcu_read_lock();
- hlist_for_each_entry_rcu(tmp_neigh_node, node,
- &orig_node->neigh_list, list) {
-
- /* only consider if it has the same primary address ... */
- if (memcmp(orig_node->orig,
- tmp_neigh_node->orig_node->primary_addr,
- ETH_ALEN) != 0)
- continue;
-
- /* ... and is good enough to be considered */
- if (tmp_neigh_node->tq_avg < best_tq - BONDING_TQ_THRESHOLD)
- continue;
-
- /* check if we have another candidate with the same
- * mac address or interface. If we do, we won't
- * select this candidate because of possible interference. */
-
- interference_candidate = 0;
- hlist_for_each_entry_rcu(tmp_neigh_node2, node2,
- &orig_node->neigh_list, list) {
-
- if (tmp_neigh_node2 == tmp_neigh_node)
- continue;
-
- /* we only care if the other candidate is even
- * considered as candidate. */
- if (!tmp_neigh_node2->next_bond_candidate)
- continue;
-
-
- if ((tmp_neigh_node->if_incoming ==
- tmp_neigh_node2->if_incoming)
- || (memcmp(tmp_neigh_node->addr,
- tmp_neigh_node2->addr, ETH_ALEN) == 0)) {
-
- interference_candidate = 1;
- break;
- }
- }
- /* don't care further if it is an interference candidate */
- if (interference_candidate)
- continue;
-
- if (!first_candidate) {
- first_candidate = tmp_neigh_node;
- tmp_neigh_node->next_bond_candidate = first_candidate;
- } else
- tmp_neigh_node->next_bond_candidate = last_candidate;
-
- last_candidate = tmp_neigh_node;
-
- candidates++;
- }
- rcu_read_unlock();
-
- if (candidates > 0) {
- first_candidate->next_bond_candidate = last_candidate;
- orig_node->bond.selected = first_candidate;
- }
-
- orig_node->bond.candidates = candidates;
-}
-
void receive_bat_packet(struct ethhdr *ethhdr,
- struct batman_packet *batman_packet,
- unsigned char *hna_buff, int hna_buff_len,
- struct batman_if *if_incoming)
+ struct batman_packet *batman_packet,
+ unsigned char *hna_buff, int hna_buff_len,
+ struct batman_if *if_incoming)
{
struct bat_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
struct batman_if *batman_if;
@@ -795,6 +779,8 @@ void receive_bat_packet(struct ethhdr *ethhdr,
is_bidirectional = is_bidirectional_neigh(orig_node, orig_neigh_node,
batman_packet, if_incoming);

+ bonding_save_primary(orig_node, orig_neigh_node, batman_packet);
+
/* update ranking if it is not a duplicate or has the same
* seqno and similar ttl as the non-duplicate */
if (is_bidirectional &&
@@ -804,9 +790,6 @@ void receive_bat_packet(struct ethhdr *ethhdr,
update_orig(bat_priv, orig_node, ethhdr, batman_packet,
if_incoming, hna_buff, hna_buff_len, is_duplicate);

- mark_bonding_address(orig_node, orig_neigh_node, batman_packet);
- update_bonding_candidates(orig_node);
-
/* is single hop (direct) neighbor */
if (is_single_hop_neigh) {

@@ -1095,14 +1078,15 @@ int recv_icmp_packet(struct sk_buff *skb, struct batman_if *recv_if)
}

/* find a suitable router for this originator, and use
- * bonding if possible. */
+ * bonding if possible. increases the found neighbors
+ * refcount.*/
struct neigh_node *find_router(struct bat_priv *bat_priv,
struct orig_node *orig_node,
struct batman_if *recv_if)
{
struct orig_node *primary_orig_node;
struct orig_node *router_orig;
- struct neigh_node *router, *first_candidate, *best_router;
+ struct neigh_node *router, *first_candidate, *tmp_neigh_node;
static uint8_t zero_mac[ETH_ALEN] = {0, 0, 0, 0, 0, 0};
int bonding_enabled;

@@ -1114,18 +1098,25 @@ struct neigh_node *find_router(struct bat_priv *bat_priv,

/* without bonding, the first node should
* always choose the default router. */
-
bonding_enabled = atomic_read(&bat_priv->bonding);

- if ((!recv_if) && (!bonding_enabled))
- return orig_node->router;
-
+ rcu_read_lock();
+ /* select default router to output */
+ router = orig_node->router;
router_orig = orig_node->router->orig_node;
+ if (!router_orig) {
+ rcu_read_unlock();
+ return NULL;
+ }
+
+
+ if ((!recv_if) && (!bonding_enabled))
+ goto return_router;

/* if we have something in the primary_addr, we can search
* for a potential bonding candidate. */
if (memcmp(router_orig->primary_addr, zero_mac, ETH_ALEN) == 0)
- return orig_node->router;
+ goto return_router;

/* find the orig_node which has the primary interface. might
* even be the same as our router_orig in many cases */
@@ -1134,60 +1125,81 @@ struct neigh_node *find_router(struct bat_priv *bat_priv,
router_orig->orig, ETH_ALEN) == 0) {
primary_orig_node = router_orig;
} else {
- rcu_read_lock();
primary_orig_node = hash_find(bat_priv->orig_hash, compare_orig,
choose_orig,
router_orig->primary_addr);
- rcu_read_unlock();
-
if (!primary_orig_node)
- return orig_node->router;
+ goto return_router;
}

/* with less than 2 candidates, we can't do any
* bonding and prefer the original router. */
-
- if (primary_orig_node->bond.candidates < 2)
- return orig_node->router;
+ if (atomic_read(&primary_orig_node->bond_candidates) < 2)
+ goto return_router;

/* all nodes between should choose a candidate which
* is is not on the interface where the packet came
* in. */
- first_candidate = primary_orig_node->bond.selected;
- router = first_candidate;
+
+ first_candidate = NULL;
+ router = NULL;

if (bonding_enabled) {
/* in the bonding case, send the packets in a round
* robin fashion over the remaining interfaces. */
- do {
+
+ list_for_each_entry_rcu(tmp_neigh_node,
+ &primary_orig_node->bond_list, bonding_list) {
+ if (!first_candidate)
+ first_candidate = tmp_neigh_node;
/* recv_if == NULL on the first node. */
- if (router->if_incoming != recv_if)
+ if (tmp_neigh_node->if_incoming != recv_if) {
+ router = tmp_neigh_node;
break;
+ }
+ }

- router = router->next_bond_candidate;
- } while (router != first_candidate);
+ /* use the first candidate if nothing was found. */
+ if (!router)
+ router = first_candidate;

- primary_orig_node->bond.selected = router->next_bond_candidate;
+ /* selected should point to the next element
+ * after the current router */
+ spin_lock_bh(&primary_orig_node->neigh_list_lock);
+ /* this is a list_move(), which unfortunately
+ * does not exist as rcu version */
+ list_del_rcu(&primary_orig_node->bond_list);
+ list_add_rcu(&primary_orig_node->bond_list,
+ &router->bonding_list);
+ spin_unlock_bh(&primary_orig_node->neigh_list_lock);

} else {
/* if bonding is disabled, use the best of the
* remaining candidates which are not using
* this interface. */
- best_router = first_candidate;
+ list_for_each_entry_rcu(tmp_neigh_node,
+ &primary_orig_node->bond_list, bonding_list) {
+ if (!first_candidate)
+ first_candidate = tmp_neigh_node;

- do {
/* recv_if == NULL on the first node. */
- if ((router->if_incoming != recv_if) &&
- (router->tq_avg > best_router->tq_avg))
- best_router = router;
-
- router = router->next_bond_candidate;
- } while (router != first_candidate);
+ if (tmp_neigh_node->if_incoming != recv_if)
+ /* if we don't have a router yet
+ * or this one is better, choose it. */
+ if ((!router) ||
+ (tmp_neigh_node->tq_avg > router->tq_avg)) {
+ router = tmp_neigh_node;
+ }
+ }

- router = best_router;
+ /* use the first candidate if nothing was found. */
+ if (!router)
+ router = first_candidate;
}
-
+return_router:
+ kref_get(&router->refcount);
+ rcu_read_unlock();
return router;
}

@@ -1247,6 +1259,7 @@ int route_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if,
unicast_packet->dest));
rcu_read_unlock();

+ /* find_router() increases neigh_nodes refcount if found. */
router = find_router(bat_priv, orig_node, recv_if);

if (!router) {
diff --git a/net/batman-adv/routing.h b/net/batman-adv/routing.h
index a09d16f..e2a9872 100644
--- a/net/batman-adv/routing.h
+++ b/net/batman-adv/routing.h
@@ -39,7 +39,9 @@ int recv_bcast_packet(struct sk_buff *skb, struct batman_if *recv_if);
int recv_vis_packet(struct sk_buff *skb, struct batman_if *recv_if);
int recv_bat_packet(struct sk_buff *skb, struct batman_if *recv_if);
struct neigh_node *find_router(struct bat_priv *bat_priv,
- struct orig_node *orig_node, struct batman_if *recv_if);
-void update_bonding_candidates(struct orig_node *orig_node);
+ struct orig_node *orig_node,
+ struct batman_if *recv_if);
+void bonding_candidate_del(struct orig_node *orig_node,
+ struct neigh_node *neigh_node);

#endif /* _NET_BATMAN_ADV_ROUTING_H_ */
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index ff70afc..1f833f0 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -90,10 +90,8 @@ struct orig_node {
struct bat_priv *bat_priv;
unsigned long last_frag_packet;
spinlock_t ogm_cnt_lock; /* protects ogm counter */
- struct {
- uint8_t candidates;
- struct neigh_node *selected;
- } bond;
+ atomic_t bond_candidates;
+ struct list_head bond_list;
};

struct gw_node {
@@ -116,11 +114,12 @@ struct neigh_node {
uint8_t tq_index;
uint8_t tq_avg;
uint8_t last_ttl;
- struct neigh_node *next_bond_candidate;
+ struct list_head bonding_list;
unsigned long last_valid;
unsigned long real_bits[NUM_WORDS];
struct kref refcount;
struct rcu_head rcu;
+ struct rcu_head rcu_bond;
struct orig_node *orig_node;
struct batman_if *if_incoming;
};
diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index 4687027..00bfeaf 100644
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -299,6 +299,7 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
if (!orig_node)
orig_node = transtable_search(bat_priv, ethhdr->h_dest);

+ /* find_router() increases neigh_nodes refcount if found. */
router = find_router(bat_priv, orig_node, NULL);

if (!router)
@@ -306,7 +307,6 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)

/* don't lock while sending the packets ... we therefore
* copy the required data before sending */
-
batman_if = router->if_incoming;
memcpy(dstaddr, router->addr, ETH_ALEN);

--
1.7.2.3