rxrpc: Make service connection lookup always check for retry

When an RxRPC service packet comes in, the target connection is looked up
by an rb-tree search under RCU and a read-locked seqlock; the seqlock retry
check is, however, currently skipped if we got a match, but probably
shouldn't be in case the connection we found gets replaced whilst we're
doing a search.

Make the lookup procedure always go through need_seqretry(), even if the
lookup was successful.  This makes sure we always pick up on a write-lock
event.

On the other hand, since we don't take a ref on the object, but rely on RCU
to prevent its destruction after dropping the seqlock, I'm not sure this is
necessary.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
index e60fcd2a4a021b2b242b2afe831e41ae99ebafae..f6fcdb3130a19a9bcb74b2d7dd5af7886ed8912d 100644 (file)
--- a/net/rxrpc/conn_service.c
+++ b/net/rxrpc/conn_service.c
@@ -50,12 +50,11 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
                        else if (conn->proto.index_key > k.index_key)
                                p = rcu_dereference_raw(p->rb_right);
                        else
-                               goto done;
+                               break;
                        conn = NULL;
                }
        } while (need_seqretry(&peer->service_conn_lock, seq));
 
-done:
        done_seqretry(&peer->service_conn_lock, seq);
        _leave(" = %d", conn ? conn->debug_id : -1);
        return conn;