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>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/tipc/name_distr.h b/net/tipc/name_distr.h
index 9b312ccfd43e..47ff829f9361 100644
--- a/net/tipc/name_distr.h
+++ b/net/tipc/name_distr.h
@@ -39,8 +39,9 @@
 
 #include "name_table.h"
 
-void tipc_named_publish(struct publication *publ);
-void tipc_named_withdraw(struct publication *publ);
+struct sk_buff *tipc_named_publish(struct publication *publ);
+struct sk_buff *tipc_named_withdraw(struct publication *publ);
+void named_cluster_distribute(struct sk_buff *buf);
 void tipc_named_node_up(unsigned long node);
 void tipc_named_rcv(struct sk_buff *buf);
 void tipc_named_reinit(void);