path: root/net/tipc
diff options
authorJon Maloy <jon.maloy@ericsson.com>2018-10-19 19:55:40 +0200
committerDavid S. Miller <davem@davemloft.net>2018-10-22 19:29:12 -0700
commit988f3f1603d4650409db5334355cbf7b13ef50c3 (patch)
tree11fcd3acceadc832e6ef9eb1e86eb5b54153b6b2 /net/tipc
parenteec6f752f7241cc914cef0b832e1c99f81ba166a (diff)
tipc: eliminate message disordering during binding table update
We have seen the following race scenario: 1) named_distribute() builds a "bulk" message, containing a PUBLISH item for a certain publication. This is based on the contents of the binding tables's 'cluster_scope' list. 2) tipc_named_withdraw() removes the same publication from the list, bulds a WITHDRAW message and distributes it to all cluster nodes. 3) tipc_named_node_up(), which was calling named_distribute(), sends out the bulk message built under 1) 4) The WITHDRAW message arrives at the just detected node, finds no corresponding publication, and is dropped. 5) The PUBLISH item arrives at the same node, is added to its binding table, and remains there forever. This arrival disordering was earlier taken care of by the backlog queue, originally added for a different purpose, which was removed in the commit referred to below, but we now need a different solution. In this commit, we replace the rcu lock protecting the 'cluster_scope' list with a regular RW lock which comprises even the sending of the bulk message. This both guarantees both the list integrity and the message sending order. We will later add a commit which cleans up this code further. Note that this commit needs recently added commit d3092b2efca1 ("tipc: fix unsafe rcu locking when accessing publication list") to apply cleanly. Fixes: 37922ea4a310 ("tipc: permit overlapping service ranges in name table") Reported-by: Tuong Lien Tong <tuong.t.lien@dektech.com.au> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
3 files changed, 12 insertions, 8 deletions
diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index 3cfeb9df64b0..61219f0b9677 100644
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -94,8 +94,9 @@ struct sk_buff *tipc_named_publish(struct net *net, struct publication *publ)
list_add_tail_rcu(&publ->binding_node, &nt->node_scope);
return NULL;
- list_add_tail_rcu(&publ->binding_node, &nt->cluster_scope);
+ write_lock_bh(&nt->cluster_scope_lock);
+ list_add_tail(&publ->binding_node, &nt->cluster_scope);
+ write_unlock_bh(&nt->cluster_scope_lock);
skb = named_prepare_buf(net, PUBLICATION, ITEM_SIZE, 0);
if (!skb) {
pr_warn("Publication distribution failure\n");
@@ -112,11 +113,13 @@ struct sk_buff *tipc_named_publish(struct net *net, struct publication *publ)
struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *publ)
+ struct name_table *nt = tipc_name_table(net);
struct sk_buff *buf;
struct distr_item *item;
- list_del_rcu(&publ->binding_node);
+ write_lock_bh(&nt->cluster_scope_lock);
+ list_del(&publ->binding_node);
+ write_unlock_bh(&nt->cluster_scope_lock);
if (publ->scope == TIPC_NODE_SCOPE)
return NULL;
@@ -147,7 +150,7 @@ static void named_distribute(struct net *net, struct sk_buff_head *list,
u32 msg_rem = msg_dsz;
- list_for_each_entry_rcu(publ, pls, binding_node) {
+ list_for_each_entry(publ, pls, binding_node) {
/* Prepare next buffer: */
if (!skb) {
skb = named_prepare_buf(net, PUBLICATION, msg_rem,
@@ -189,11 +192,10 @@ void tipc_named_node_up(struct net *net, u32 dnode)
- rcu_read_lock();
+ read_lock_bh(&nt->cluster_scope_lock);
named_distribute(net, &head, dnode, &nt->cluster_scope);
- rcu_read_unlock();
tipc_node_xmit(net, &head, dnode, 0);
+ read_unlock_bh(&nt->cluster_scope_lock);
diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index 66d5b2c5987a..bff241f03525 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -744,6 +744,7 @@ int tipc_nametbl_init(struct net *net)
+ rwlock_init(&nt->cluster_scope_lock);
tn->nametbl = nt;
return 0;
diff --git a/net/tipc/name_table.h b/net/tipc/name_table.h
index 892bd750b85f..f79066334cc8 100644
--- a/net/tipc/name_table.h
+++ b/net/tipc/name_table.h
@@ -100,6 +100,7 @@ struct name_table {
struct hlist_head services[TIPC_NAMETBL_SIZE];
struct list_head node_scope;
struct list_head cluster_scope;
+ rwlock_t cluster_scope_lock;
u32 local_publ_count;