[Patch net] tipc: use lock_sock() in tipc_sk_reinit()

[Cong Wang]

lock_sock() must be used in process context to be race-free with
other lock_sock() callers, for example, tipc_release(). Otherwise
using the spinlock directly can't serialize a parallel tipc_release().

As it is blocking, we have to hold the sock refcnt before
rhashtable_walk_stop() and release it after rhashtable_walk_start().

Fixes: 07f6c4bc048a ("tipc: convert tipc reference table to use generic 
rhashtable")
Reported-by: Dmitry Vyukov <dvyu...@google.com>
Cc: Ying Xue <ying....@windriver.com>
Cc: Jon Maloy <jon.ma...@ericsson.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/tipc/socket.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b57b1be7252b..e1396fb87779 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2724,11 +2724,15 @@ void tipc_sk_reinit(struct net *net)
                rhashtable_walk_start(&iter);
 
                while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
-                       spin_lock_bh(&tsk->sk.sk_lock.slock);
+                       sock_hold(&tsk->sk);
+                       rhashtable_walk_stop(&iter);
+                       lock_sock(&tsk->sk);
                        msg = &tsk->phdr;
                        msg_set_prevnode(msg, tipc_own_addr(net));
                        msg_set_orignode(msg, tipc_own_addr(net));
-                       spin_unlock_bh(&tsk->sk.sk_lock.slock);
+                       release_sock(&tsk->sk);
+                       rhashtable_walk_start(&iter);
+                       sock_put(&tsk->sk);
                }
 
                rhashtable_walk_stop(&iter);
-- 
2.19.2