path: root/net/xdp
diff options
authorBjörn Töpel <bjorn.topel@intel.com>2018-10-05 13:25:15 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2018-10-08 10:09:22 +0200
commit541d7fdd7694560404c502f64298a90ffe017e6b (patch)
tree899c2c76d4f59f42a3b1ea0b1339e32f936426ca /net/xdp
parentMerge branch 'bpf-xsk-fix-mixed-mode' (diff)
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>
Diffstat (limited to 'net/xdp')
2 files changed, 11 insertions, 13 deletions
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index c6007c58231c..a264cf2accd0 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -32,14 +32,9 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
unsigned long flags;
- if (xs->dev) {
- spin_lock_irqsave(&umem->xsk_list_lock, flags);
- list_del_rcu(&xs->list);
- spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
- if (umem->zc)
- synchronize_net();
- }
+ spin_lock_irqsave(&umem->xsk_list_lock, flags);
+ list_del_rcu(&xs->list);
+ spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
/* The umem is stored both in the _rx struct and the _tx struct as we do
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index caeddad15b7c..0577cd49aa72 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -355,12 +355,18 @@ static int xsk_release(struct socket *sock)
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->sk = NULL;
@@ -714,9 +720,6 @@ static void xsk_destruct(struct sock *sk)
if (!sock_flag(sk, SOCK_DEAD))
- xskq_destroy(xs->rx);
- xskq_destroy(xs->tx);
- xdp_del_sk_umem(xs->umem, xs);