With this commit only spinlocking for reading/writing variables inside a neigh_node for NDP is used. The neigh_list traversal and entry deleting/adding is done with rcu-locking and reference counting instead to greatly reduce the time of (concurrent) spinlocking.
Signed-off-by: Linus Lüssing <[email protected]> --- ndp.c | 58 ++++++++++++++++++++++++++++++++++++++++------------------ originator.c | 2 +- originator.h | 1 + routing.c | 14 +++++++++----- types.h | 2 ++ 5 files changed, 53 insertions(+), 24 deletions(-) diff --git a/batman-adv/ndp.c b/batman-adv/ndp.c index 1fd107c..87ea204 100644 --- a/batman-adv/ndp.c +++ b/batman-adv/ndp.c @@ -66,19 +66,23 @@ static void ndp_send(struct work_struct *work) ETH_ALEN); neigh_entry = (struct neigh_entry *)(ndp_packet + 1); - spin_lock_bh(&batman_if->neigh_list_lock); - hlist_for_each_entry(neigh_node, node, &batman_if->neigh_list, list) { + rcu_read_lock(); + hlist_for_each_entry_rcu(neigh_node, node, &batman_if->neigh_list, + list) { if (entries_len + sizeof(struct neigh_entry) > skb_tailroom(skb)) break; + spin_lock_bh(&neigh_node->update_lock); memcpy(neigh_entry->addr, neigh_node->addr, ETH_ALEN); neigh_entry->rq = neigh_node->rq; + spin_unlock_bh(&neigh_node->update_lock); + ndp_packet->num_neighbors++; neigh_entry++; entries_len += sizeof(struct neigh_entry); } - spin_unlock_bh(&batman_if->neigh_list_lock); + rcu_read_unlock(); skb_put(skb, entries_len); bat_dbg(DBG_BATMAN, bat_priv, @@ -133,8 +137,8 @@ void ndp_free(struct batman_if *batman_if) spin_lock_bh(&batman_if->neigh_list_lock); hlist_for_each_entry_safe(neigh_node, node, node_tmp, &batman_if->neigh_list, list) { - hlist_del(&neigh_node->list); - kfree(neigh_node); + hlist_del_rcu(&neigh_node->list); + call_rcu(&neigh_node->rcu, neigh_node_free_rcu); } spin_unlock_bh(&batman_if->neigh_list_lock); } @@ -216,6 +220,9 @@ static struct neigh_node *ndp_create_neighbor(uint8_t my_tq, uint32_t seqno, return NULL; INIT_HLIST_NODE(&neigh_node->list); + spin_lock_init(&neigh_node->update_lock); + kref_init(&neigh_node->refcount); + memcpy(neigh_node->addr, neigh_addr, ETH_ALEN); neigh_node->last_rq_seqno = seqno - 1; @@ -227,6 +234,7 @@ void ndp_purge_neighbors(void) struct neigh_node *neigh_node; struct hlist_node *node, *node_tmp; struct batman_if *batman_if; + unsigned long last_valid; rcu_read_lock(); list_for_each_entry_rcu(batman_if, &if_list, list) { @@ -236,13 +244,17 @@ void ndp_purge_neighbors(void) spin_lock_bh(&batman_if->neigh_list_lock); hlist_for_each_entry_safe(neigh_node, node, node_tmp, &batman_if->neigh_list, list) { - if (time_before(jiffies, neigh_node->last_valid + + spin_lock(&neigh_node->update_lock); + last_valid = neigh_node->last_valid; + spin_unlock(&neigh_node->update_lock); + + if (time_before(jiffies, last_valid + msecs_to_jiffies(PURGE_TIMEOUT * 1000))) continue; - hlist_del(&neigh_node->list); - kfree(neigh_node); + hlist_del_rcu(&neigh_node->list); + call_rcu(&neigh_node->rcu, neigh_node_free_rcu); } spin_unlock_bh(&batman_if->neigh_list_lock); } @@ -257,16 +269,17 @@ int ndp_update_neighbor(uint8_t my_tq, uint32_t seqno, struct hlist_node *node; int ret = 1; - spin_lock_bh(&batman_if->neigh_list_lock); - /* old neighbor? */ - hlist_for_each_entry(tmp_neigh_node, node, &batman_if->neigh_list, + rcu_read_lock(); + hlist_for_each_entry_rcu(tmp_neigh_node, node, &batman_if->neigh_list, list) { if (!compare_orig(tmp_neigh_node->addr, neigh_addr)) continue; neigh_node = tmp_neigh_node; + kref_get(&neigh_node->refcount); break; } + rcu_read_unlock(); /* new neighbor? */ if (!neigh_node) { @@ -275,15 +288,24 @@ int ndp_update_neighbor(uint8_t my_tq, uint32_t seqno, if (!neigh_node) goto ret; - hlist_add_head(&neigh_node->list, &batman_if->neigh_list); + ndp_update_neighbor_lq(my_tq, seqno, neigh_node, bat_priv); + + spin_lock_bh(&batman_if->neigh_list_lock); + hlist_add_head_rcu(&neigh_node->list, &batman_if->neigh_list); + spin_unlock_bh(&batman_if->neigh_list_lock); } + /* old neighbor? */ + else { + spin_lock_bh(&neigh_node->update_lock); + ndp_update_neighbor_lq(my_tq, seqno, neigh_node, bat_priv); + spin_unlock_bh(&neigh_node->update_lock); - ndp_update_neighbor_lq(my_tq, seqno, neigh_node, bat_priv); + kref_put(&neigh_node->refcount, neigh_node_free_ref); + } ret = 0; ret: - spin_unlock_bh(&batman_if->neigh_list_lock); return ret; } @@ -322,9 +344,9 @@ int ndp_seq_print_text(struct seq_file *seq, void *offset) if (batman_if->if_status != IF_ACTIVE) continue; - spin_lock_bh(&batman_if->neigh_list_lock); - hlist_for_each_entry(neigh_node, node, &batman_if->neigh_list, - list) { + hlist_for_each_entry_rcu(neigh_node, node, + &batman_if->neigh_list, list) { + spin_lock_bh(&neigh_node->update_lock); last_seen_secs = jiffies_to_msecs(jiffies - neigh_node->last_valid) / 1000; last_seen_msecs = jiffies_to_msecs(jiffies - @@ -335,9 +357,9 @@ int ndp_seq_print_text(struct seq_file *seq, void *offset) last_seen_msecs, neigh_node->tq_avg, neigh_node->rq, batman_if->net_dev->name); + spin_unlock_bh(&neigh_node->update_lock); batman_count++; } - spin_unlock_bh(&batman_if->neigh_list_lock); } rcu_read_unlock(); diff --git a/batman-adv/originator.c b/batman-adv/originator.c index e98add5..699dbfc 100644 --- a/batman-adv/originator.c +++ b/batman-adv/originator.c @@ -68,7 +68,7 @@ void neigh_node_free_ref(struct kref *refcount) kfree(neigh_node); } -static void neigh_node_free_rcu(struct rcu_head *rcu) +void neigh_node_free_rcu(struct rcu_head *rcu) { struct neigh_node *neigh_node; diff --git a/batman-adv/originator.h b/batman-adv/originator.h index f3676fa..2a7d68b 100644 --- a/batman-adv/originator.h +++ b/batman-adv/originator.h @@ -31,6 +31,7 @@ struct neigh_node *create_neighbor(struct orig_node *orig_node, uint8_t *neigh, struct batman_if *if_incoming); void neigh_node_free_ref(struct kref *refcount); +void neigh_node_free_rcu(struct rcu_head *rcu); int orig_seq_print_text(struct seq_file *seq, void *offset); int orig_hash_add_if(struct batman_if *batman_if, int max_if_num); int orig_hash_del_if(struct batman_if *batman_if, int max_if_num); diff --git a/batman-adv/routing.c b/batman-adv/routing.c index 8a3acfa..785ddc2 100644 --- a/batman-adv/routing.c +++ b/batman-adv/routing.c @@ -199,20 +199,24 @@ static int is_bidirectional_neigh(struct orig_node *orig_node, return 0; } - /* note, bottom halves are already deactivated outside in - * recv_bat_packet() */ - spin_lock(&if_incoming->neigh_list_lock); - hlist_for_each_entry(neigh_node, node, &if_incoming->neigh_list, + rcu_read_lock(); + hlist_for_each_entry_rcu(neigh_node, node, &if_incoming->neigh_list, list) { if (!compare_orig(neigh_node->addr, orig_neigh_node->orig)) continue; orig_node->last_valid = jiffies; + + /* note, bottom halves are already deactivated outside in + * recv_bat_packet() */ + spin_lock(&neigh_node->update_lock); local_tq = neigh_node->tq_avg; local_rq = neigh_node->rq; + spin_unlock(&neigh_node->update_lock); + break; } - spin_unlock(&if_incoming->neigh_list_lock); + rcu_read_unlock(); if (local_tq == 0) return 0; diff --git a/batman-adv/types.h b/batman-adv/types.h index 5a21611..37b4eef 100644 --- a/batman-adv/types.h +++ b/batman-adv/types.h @@ -129,6 +129,8 @@ struct neigh_node { struct rcu_head rcu; struct orig_node *orig_node; struct batman_if *if_incoming; + spinlock_t update_lock; /* protects last_rq_seqno, ndp_rq_window, rq, + last_valid, tq_avg for NDP */ }; struct neigh_entry { -- 1.7.1
