tipc: Fix tipc_sk_reinit handling of -EAGAIN

In 9dbbfb0ab6680c6a85609041011484e6658e7d3c function tipc_sk_reinit
had additional logic added to loop in the event that function
rhashtable_walk_next() returned -EAGAIN. No worries.

However, if rhashtable_walk_start returns -EAGAIN, it does "continue",
and therefore skips the call to rhashtable_walk_stop(). That has
the effect of calling rcu_read_lock() without its paired call to
rcu_read_unlock(). Since rcu_read_lock() may be nested, the problem
may not be apparent for a while, especially since resize events may
be rare. But the comments to rhashtable_walk_start() state:

 * ...Note that we take the RCU lock in all
 * cases including when we return an error.  So you must always call
 * rhashtable_walk_stop to clean up.

This patch replaces the continue with a goto and label to ensure a
matching call to rhashtable_walk_stop().

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 101e3597338f7c1e182c9090af0d14caf5be1b8b..d50edd6e00196af04ee7a4011d6339b100cb3537 100644 (file)
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2255,8 +2255,8 @@ void tipc_sk_reinit(struct net *net)
 
        do {
                tsk = ERR_PTR(rhashtable_walk_start(&iter));
-               if (tsk)
-                       continue;
+               if (IS_ERR(tsk))
+                       goto walk_stop;
 
                while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
                        spin_lock_bh(&tsk->sk.sk_lock.slock);
@@ -2265,7 +2265,7 @@ void tipc_sk_reinit(struct net *net)
                        msg_set_orignode(msg, tn->own_addr);
                        spin_unlock_bh(&tsk->sk.sk_lock.slock);
                }
-
+walk_stop:
                rhashtable_walk_stop(&iter);
        } while (tsk == ERR_PTR(-EAGAIN));
 }