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_table.c b/net/tipc/name_table.c
index 042e8e3..9bcf4b5 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -664,6 +664,7 @@
u32 scope, u32 port_ref, u32 key)
{
struct publication *publ;
+ struct sk_buff *buf = NULL;
if (table.local_publ_count >= TIPC_MAX_PUBLICATIONS) {
pr_warn("Publication failed, local publication limit reached (%u)\n",
@@ -676,9 +677,12 @@
tipc_own_addr, port_ref, key);
if (likely(publ)) {
table.local_publ_count++;
- tipc_named_publish(publ);
+ buf = tipc_named_publish(publ);
}
write_unlock_bh(&tipc_nametbl_lock);
+
+ if (buf)
+ named_cluster_distribute(buf);
return publ;
}
@@ -688,15 +692,19 @@
int tipc_nametbl_withdraw(u32 type, u32 lower, u32 ref, u32 key)
{
struct publication *publ;
+ struct sk_buff *buf;
write_lock_bh(&tipc_nametbl_lock);
publ = tipc_nametbl_remove_publ(type, lower, tipc_own_addr, ref, key);
if (likely(publ)) {
table.local_publ_count--;
- tipc_named_withdraw(publ);
+ buf = tipc_named_withdraw(publ);
write_unlock_bh(&tipc_nametbl_lock);
list_del_init(&publ->pport_list);
kfree(publ);
+
+ if (buf)
+ named_cluster_distribute(buf);
return 1;
}
write_unlock_bh(&tipc_nametbl_lock);
