batman-adv: protect neighbor list with rcu locks

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

3 files changed, 57 insertions, 21 deletions

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 68b04e77f4d7..6cb9af3f89e5 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -67,6 +67,14 @@ void neigh_node_free_ref(struct kref *refcount)
         kfree(neigh_node);
 }
 
+static void neigh_node_free_rcu(struct rcu_head *rcu)
+{
+        struct neigh_node *neigh_node;
+
+        neigh_node = container_of(rcu, struct neigh_node, rcu);
+        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,
@@ -89,7 +97,9 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node,
         neigh_node->if_incoming = if_incoming;
         kref_init(&neigh_node->refcount);
 
-        hlist_add_head(&neigh_node->list, &orig_node->neigh_list);
+        spin_lock_bh(&orig_node->neigh_list_lock);
+        hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
+        spin_unlock_bh(&orig_node->neigh_list_lock);
         return neigh_node;
 }
 
@@ -100,13 +110,17 @@ static void free_orig_node(void *data, void *arg)
         struct orig_node *orig_node = (struct orig_node *)data;
         struct bat_priv *bat_priv = (struct bat_priv *)arg;
 
+        spin_lock_bh(&orig_node->neigh_list_lock);
+
         /* for all neighbors towards this originator ... */
         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
                                   &orig_node->neigh_list, list) {
-                hlist_del(&neigh_node->list);
-                kref_put(&neigh_node->refcount, neigh_node_free_ref);
+                hlist_del_rcu(&neigh_node->list);
+                call_rcu(&neigh_node->rcu, neigh_node_free_rcu);
         }
 
+        spin_unlock_bh(&orig_node->neigh_list_lock);
+
         frag_list_free(&orig_node->frag_list);
         hna_global_del_orig(bat_priv, orig_node, "originator timed out");
 
@@ -151,6 +165,7 @@ struct orig_node *get_orig_node(struct bat_priv *bat_priv, uint8_t *addr)
                 return NULL;
 
         INIT_HLIST_HEAD(&orig_node->neigh_list);
+        spin_lock_init(&orig_node->neigh_list_lock);
 
         memcpy(orig_node->orig, addr, ETH_ALEN);
         orig_node->router = NULL;
@@ -200,6 +215,8 @@ static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 
         *best_neigh_node = NULL;
 
+        spin_lock_bh(&orig_node->neigh_list_lock);
+
         /* for all neighbors towards this originator ... */
         hlist_for_each_entry_safe(neigh_node, node, node_tmp,
                                   &orig_node->neigh_list, list) {
@@ -225,14 +242,16 @@ static bool purge_orig_neighbors(struct bat_priv *bat_priv,
 
                         neigh_purged = true;
 
-                        hlist_del(&neigh_node->list);
-                        kref_put(&neigh_node->refcount, neigh_node_free_ref);
+                        hlist_del_rcu(&neigh_node->list);
+                        call_rcu(&neigh_node->rcu, neigh_node_free_rcu);
                 } else {
                         if ((!*best_neigh_node) ||
                             (neigh_node->tq_avg > (*best_neigh_node)->tq_avg))
                                 *best_neigh_node = neigh_node;
                 }
         }
+
+        spin_unlock_bh(&orig_node->neigh_list_lock);
         return neigh_purged;
 }
 
@@ -384,11 +403,13 @@ int orig_seq_print_text(struct seq_file *seq, void *offset)
                                    neigh_node->addr,
                                    neigh_node->if_incoming->net_dev->name);
 
-                        hlist_for_each_entry(neigh_node, node,
-                                             &orig_node->neigh_list, list) {
+                        rcu_read_lock();
+                        hlist_for_each_entry_rcu(neigh_node, node,
+                                                 &orig_node->neigh_list, list) {
                                 seq_printf(seq, " %pM (%3i)", neigh_node->addr,
                                                 neigh_node->tq_avg);
                         }
+                        rcu_read_unlock();
 
                         seq_printf(seq, "\n");
                         batman_count++;
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index e8379ba25e95..97f321615686 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -153,14 +153,16 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
         unsigned char total_count;
 
         if (orig_node == orig_neigh_node) {
-                hlist_for_each_entry(tmp_neigh_node, node,
-                                     &orig_node->neigh_list, list) {
+                rcu_read_lock();
+                hlist_for_each_entry_rcu(tmp_neigh_node, node,
+                                         &orig_node->neigh_list, list) {
 
                         if (compare_orig(tmp_neigh_node->addr,
                                          orig_neigh_node->orig) &&
                             (tmp_neigh_node->if_incoming == if_incoming))
                                 neigh_node = tmp_neigh_node;
                 }
+                rcu_read_unlock();
 
                 if (!neigh_node)
                         neigh_node = create_neighbor(orig_node,
@@ -174,14 +176,16 @@ static int is_bidirectional_neigh(struct orig_node *orig_node,
                 neigh_node->last_valid = jiffies;
         } else {
                 /* find packet count of corresponding one hop neighbor */
-                hlist_for_each_entry(tmp_neigh_node, node,
-                                     &orig_neigh_node->neigh_list, list) {
+                rcu_read_lock();
+                hlist_for_each_entry_rcu(tmp_neigh_node, node,
+                                         &orig_neigh_node->neigh_list, list) {
 
                         if (compare_orig(tmp_neigh_node->addr,
                                          orig_neigh_node->orig) &&
                             (tmp_neigh_node->if_incoming == if_incoming))
                                 neigh_node = tmp_neigh_node;
                 }
+                rcu_read_unlock();
 
                 if (!neigh_node)
                         neigh_node = create_neighbor(orig_neigh_node,
@@ -266,8 +270,9 @@ static void update_orig(struct bat_priv *bat_priv,
         bat_dbg(DBG_BATMAN, bat_priv, "update_originator(): "
                 "Searching and updating originator entry of received packet\n");
 
-        hlist_for_each_entry(tmp_neigh_node, node,
-                             &orig_node->neigh_list, list) {
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(tmp_neigh_node, node,
+                                 &orig_node->neigh_list, list) {
                 if (compare_orig(tmp_neigh_node->addr, ethhdr->h_source) &&
                     (tmp_neigh_node->if_incoming == if_incoming)) {
                         neigh_node = tmp_neigh_node;
@@ -282,6 +287,7 @@ static void update_orig(struct bat_priv *bat_priv,
                 tmp_neigh_node->tq_avg =
                         ring_buffer_avg(tmp_neigh_node->tq_recv);
         }
+        rcu_read_unlock();
 
         if (!neigh_node) {
                 struct orig_node *orig_tmp;
@@ -410,8 +416,9 @@ static char count_real_packets(struct ethhdr *ethhdr,
                              &orig_node->batman_seqno_reset))
                 return -1;
 
-        hlist_for_each_entry(tmp_neigh_node, node,
-                             &orig_node->neigh_list, list) {
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(tmp_neigh_node, node,
+                                 &orig_node->neigh_list, list) {
 
                 is_duplicate |= get_bit_status(tmp_neigh_node->real_bits,
                                                orig_node->last_real_seqno,
@@ -431,6 +438,7 @@ static char count_real_packets(struct ethhdr *ethhdr,
                 tmp_neigh_node->real_packet_count =
                         bit_packet_count(tmp_neigh_node->real_bits);
         }
+        rcu_read_unlock();
 
         if (need_update) {
                 bat_dbg(DBG_BATMAN, bat_priv,
@@ -481,15 +489,19 @@ void update_bonding_candidates(struct orig_node *orig_node)
          * as "bonding partner" */
 
         /* first, zero the list */
-        hlist_for_each_entry(tmp_neigh_node, node,
-                             &orig_node->neigh_list, 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;
-        hlist_for_each_entry(tmp_neigh_node, node,
-                             &orig_node->neigh_list, list) {
+
+        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,
@@ -506,8 +518,8 @@ void update_bonding_candidates(struct orig_node *orig_node)
                  * select this candidate because of possible interference. */
 
                 interference_candidate = 0;
-                hlist_for_each_entry(tmp_neigh_node2, node2,
-                                     &orig_node->neigh_list, list) {
+                hlist_for_each_entry_rcu(tmp_neigh_node2, node2,
+                                         &orig_node->neigh_list, list) {
 
                         if (tmp_neigh_node2 == tmp_neigh_node)
                                 continue;
@@ -541,6 +553,7 @@ void update_bonding_candidates(struct orig_node *orig_node)
 
                 candidates++;
         }
+        rcu_read_unlock();
 
         if (candidates > 0) {
                 first_candidate->next_bond_candidate = last_candidate;
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 779c5c30bd04..d4fa727aece3 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -85,6 +85,7 @@ struct orig_node {
         uint32_t last_bcast_seqno;
         struct hlist_head neigh_list;
         struct list_head frag_list;
+        spinlock_t neigh_list_lock; /* protects neighbor list */
         unsigned long last_frag_packet;
         struct {
                 uint8_t candidates;
@@ -116,6 +117,7 @@ struct neigh_node {
         unsigned long last_valid;
         unsigned long real_bits[NUM_WORDS];
         struct kref refcount;
+        struct rcu_head rcu;
         struct orig_node *orig_node;
         struct batman_if *if_incoming;
 };