xsk: proper AF_XDP socket teardown ordering
The AF_XDP socket struct can exist in three different, implicit
states: setup, bound and released. Setup is prior the socket has been
bound to a device. Bound is when the socket is active for receive and
send. Released is when the process/userspace side of the socket is
released, but the sock object is still lingering, e.g. when there is a
reference to the socket in an XSKMAP after process termination.
The Rx fast-path code uses the "dev" member of struct xdp_sock to
check whether a socket is bound or relased, and the Tx code uses the
struct xdp_umem "xsk_list" member in conjunction with "dev" to
determine the state of a socket.
However, the transition from bound to released did not tear the socket
down in correct order.
On the Rx side "dev" was cleared after synchronize_net() making the
synchronization useless. On the Tx side, the internal queues were
destroyed prior removing them from the "xsk_list".
This commit corrects the cleanup order, and by doing so
xdp_del_sk_umem() can be simplified and one synchronize_net() can be
removed.
Fixes: 965a99098443 ("xsk: add support for bind for Rx")
Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions")
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index caeddad1..0577cd4 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -355,12 +355,18 @@ static int xsk_release(struct socket *sock)
local_bh_enable();
if (xs->dev) {
+ struct net_device *dev = xs->dev;
+
/* Wait for driver to stop using the xdp socket. */
- synchronize_net();
- dev_put(xs->dev);
+ xdp_del_sk_umem(xs->umem, xs);
xs->dev = NULL;
+ synchronize_net();
+ dev_put(dev);
}
+ xskq_destroy(xs->rx);
+ xskq_destroy(xs->tx);
+
sock_orphan(sk);
sock->sk = NULL;
@@ -714,9 +720,6 @@ static void xsk_destruct(struct sock *sk)
if (!sock_flag(sk, SOCK_DEAD))
return;
- xskq_destroy(xs->rx);
- xskq_destroy(xs->tx);
- xdp_del_sk_umem(xs->umem, xs);
xdp_put_umem(xs->umem);
sk_refcnt_debug_dec(sk);