Merge branch 'bpf-fix-xsk-wakeup'

Maxim Mikityanskiy says:

====================
This series addresses the issue described in the commit message of the
first patch: lack of synchronization between XSK wakeup and destroying
the resources used by XSK wakeup. The idea is similar to napi_synchronize.
The series contains fixes for the drivers that implement XSK.

v2 incorporates changes suggested by Björn:

1. Call synchronize_rcu in Intel drivers only if the XDP program is
   being unloaded.
2. Don't forget rcu_read_lock when wakeup is called from xsk_poll.
3. Use xs->zc as the condition to call ndo_xsk_wakeup.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 14 insertions, 8 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 956793893c9d..328f661b83b2 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -334,12 +334,21 @@ out:
 }
 EXPORT_SYMBOL(xsk_umem_consume_tx);
 
-static int xsk_zc_xmit(struct xdp_sock *xs)
+static int xsk_wakeup(struct xdp_sock *xs, u8 flags)
 {
 	struct net_device *dev = xs->dev;
+	int err;
+
+	rcu_read_lock();
+	err = dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, flags);
+	rcu_read_unlock();
+
+	return err;
+}
 
-	return dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id,
-					       XDP_WAKEUP_TX);
+static int xsk_zc_xmit(struct xdp_sock *xs)
+{
+	return xsk_wakeup(xs, XDP_WAKEUP_TX);
 }
 
 static void xsk_destruct_skb(struct sk_buff *skb)
@@ -453,19 +462,16 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
 	__poll_t mask = datagram_poll(file, sock, wait);
 	struct sock *sk = sock->sk;
 	struct xdp_sock *xs = xdp_sk(sk);
-	struct net_device *dev;
 	struct xdp_umem *umem;
 
 	if (unlikely(!xsk_is_bound(xs)))
 		return mask;
 
-	dev = xs->dev;
 	umem = xs->umem;
 
 	if (umem->need_wakeup) {
-		if (dev->netdev_ops->ndo_xsk_wakeup)
-			dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id,
-							umem->need_wakeup);
+		if (xs->zc)
+			xsk_wakeup(xs, umem->need_wakeup);
 		else
 			/* Poll needs to drive Tx also in copy mode */
 			__xsk_sendmsg(sk);