tipc: move the delivery of named messages out of nametbl lock
Commit a89778d8baf19cd7e728d81121a294a06cedaad1 ("tipc: add support
for link state subscriptions") introduced below possible deadlock
scenario:
CPU0 CPU1
T0: tipc_publish() link_timeout()
T1: tipc_nametbl_publish() [grab node lock]*
T2: [grab nametbl write lock]* link_state_event()
T3: named_cluster_distribute() link_activate()
T4: [grab node lock]* tipc_node_link_up()
T5: tipc_nametbl_publish()
T6: [grab nametble write lock]*
The opposite order of holding nametbl write lock and node lock on
above two different paths may result in a deadlock. If we move the
the delivery of named messages via link out of name nametbl lock,
the reverse order of holding locks will be eliminated, as a result,
the deadlock will be killed as well.
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index 36a7282..974a73f 100644
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -127,7 +127,7 @@
return buf;
}
-static void named_cluster_distribute(struct sk_buff *buf)
+void named_cluster_distribute(struct sk_buff *buf)
{
struct sk_buff *buf_copy;
struct tipc_node *n_ptr;
@@ -156,7 +156,7 @@
/**
* tipc_named_publish - tell other nodes about a new publication by this node
*/
-void tipc_named_publish(struct publication *publ)
+struct sk_buff *tipc_named_publish(struct publication *publ)
{
struct sk_buff *buf;
struct distr_item *item;
@@ -165,23 +165,23 @@
publ_lists[publ->scope]->size++;
if (publ->scope == TIPC_NODE_SCOPE)
- return;
+ return NULL;
buf = named_prepare_buf(PUBLICATION, ITEM_SIZE, 0);
if (!buf) {
pr_warn("Publication distribution failure\n");
- return;
+ return NULL;
}
item = (struct distr_item *)msg_data(buf_msg(buf));
publ_to_item(item, publ);
- named_cluster_distribute(buf);
+ return buf;
}
/**
* tipc_named_withdraw - tell other nodes about a withdrawn publication by this node
*/
-void tipc_named_withdraw(struct publication *publ)
+struct sk_buff *tipc_named_withdraw(struct publication *publ)
{
struct sk_buff *buf;
struct distr_item *item;
@@ -190,17 +190,17 @@
publ_lists[publ->scope]->size--;
if (publ->scope == TIPC_NODE_SCOPE)
- return;
+ return NULL;
buf = named_prepare_buf(WITHDRAWAL, ITEM_SIZE, 0);
if (!buf) {
pr_warn("Withdrawal distribution failure\n");
- return;
+ return NULL;
}
item = (struct distr_item *)msg_data(buf_msg(buf));
publ_to_item(item, publ);
- named_cluster_distribute(buf);
+ return buf;
}
/*