xdp: add flags argument to ndo_xdp_xmit API

This patch only change the API and reject any use of flags. This is an
intermediate step that allows us to implement the flush flag operation
later, for each individual driver in a separate patch.

The plan is to implement flush operation via XDP_XMIT_FLUSH flag
and then remove XDP_XMIT_FLAGS_NONE when done.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

9 files changed, 32 insertions, 11 deletions

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 9b698c5acd05..c0451d6e0790 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -3670,7 +3670,8 @@ netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
  * For error cases, a negative errno code is returned and no-frames
  * are transmitted (caller must handle freeing frames).
  **/
-int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames)
+int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
+		  u32 flags)
 {
 	struct i40e_netdev_priv *np = netdev_priv(dev);
 	unsigned int queue_index = smp_processor_id();
@@ -3684,6 +3685,9 @@ int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames)
 	if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
 		return -ENXIO;
 
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_NONE))
+		return -EINVAL;
+
 	for (i = 0; i < n; i++) {
 		struct xdp_frame *xdpf = frames[i];
 		int err;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index eb8804b3d7b6..820f76db251b 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -487,7 +487,8 @@ u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw);
 void i40e_detect_recover_hung(struct i40e_vsi *vsi);
 int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size);
 bool __i40e_chk_linearize(struct sk_buff *skb);
-int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames);
+int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
+		  u32 flags);
 void i40e_xdp_flush(struct net_device *dev);
 
 /**
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 031d65c4178d..87f088f4af52 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -10023,7 +10023,7 @@ static int ixgbe_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 }
 
 static int ixgbe_xdp_xmit(struct net_device *dev, int n,
-			  struct xdp_frame **frames)
+			  struct xdp_frame **frames, u32 flags)
 {
 	struct ixgbe_adapter *adapter = netdev_priv(dev);
 	struct ixgbe_ring *ring;
@@ -10033,6 +10033,9 @@ static int ixgbe_xdp_xmit(struct net_device *dev, int n,
 	if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
 		return -ENETDOWN;
 
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_NONE))
+		return -EINVAL;
+
 	/* During program transitions its possible adapter->xdp_prog is assigned
 	 * but ring has not been configured yet. In this case simply abort xmit.
 	 */
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2265d2ccea47..b182b8cdd219 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1285,7 +1285,8 @@ static const struct net_device_ops tun_netdev_ops = {
 	.ndo_get_stats64	= tun_net_get_stats64,
 };
 
-static int tun_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames)
+static int tun_xdp_xmit(struct net_device *dev, int n,
+			struct xdp_frame **frames, u32 flags)
 {
 	struct tun_struct *tun = netdev_priv(dev);
 	struct tun_file *tfile;
@@ -1294,6 +1295,9 @@ static int tun_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames
 	int cnt = n;
 	int i;
 
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_NONE))
+		return -EINVAL;
+
 	rcu_read_lock();
 
 	numqueues = READ_ONCE(tun->numqueues);
@@ -1332,7 +1336,7 @@ static int tun_xdp_tx(struct net_device *dev, struct xdp_buff *xdp)
 	if (unlikely(!frame))
 		return -EOVERFLOW;
 
-	return tun_xdp_xmit(dev, 1, &frame);
+	return tun_xdp_xmit(dev, 1, &frame, 0);
 }
 
 static void tun_xdp_flush(struct net_device *dev)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b2647dd5d302..4ed823625953 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -468,7 +468,7 @@ static int __virtnet_xdp_tx_xmit(struct virtnet_info *vi,
 }
 
 static int virtnet_xdp_xmit(struct net_device *dev,
-			    int n, struct xdp_frame **frames)
+			    int n, struct xdp_frame **frames, u32 flags)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 	struct receive_queue *rq = vi->rq;
@@ -481,6 +481,9 @@ static int virtnet_xdp_xmit(struct net_device *dev,
 	int err;
 	int i;
 
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_NONE))
+		return -EINVAL;
+
 	qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
 	sq = &vi->sq[qp];
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 8452f72087ef..7f17785a59d7 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1185,13 +1185,13 @@ struct dev_ifalias {
  *	This function is used to set or query state related to XDP on the
  *	netdevice and manage BPF offload. See definition of
  *	enum bpf_netdev_command for details.
- * int (*ndo_xdp_xmit)(struct net_device *dev, int n, struct xdp_frame **xdp);
+ * int (*ndo_xdp_xmit)(struct net_device *dev, int n, struct xdp_frame **xdp,
+ *			u32 flags);
  *	This function is used to submit @n XDP packets for transmit on a
  *	netdevice. Returns number of frames successfully transmitted, frames
  *	that got dropped are freed/returned via xdp_return_frame().
  *	Returns negative number, means general error invoking ndo, meaning
  *	no frames were xmit'ed and core-caller will free all frames.
- *	TODO: Consider add flag to allow sending flush operation.
  * void (*ndo_xdp_flush)(struct net_device *dev);
  *	This function is used to inform the driver to flush a particular
  *	xdp tx queue. Must be called on same CPU as xdp_xmit.
@@ -1380,7 +1380,8 @@ struct net_device_ops {
 	int			(*ndo_bpf)(struct net_device *dev,
 					   struct netdev_bpf *bpf);
 	int			(*ndo_xdp_xmit)(struct net_device *dev, int n,
-						struct xdp_frame **xdp);
+						struct xdp_frame **xdp,
+						u32 flags);
 	void			(*ndo_xdp_flush)(struct net_device *dev);
 };
 
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 7ad779237ae8..0c45f0f943ed 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -40,6 +40,11 @@ enum xdp_mem_type {
 	MEM_TYPE_MAX,
 };
 
+/* XDP flags for ndo_xdp_xmit */
+#define XDP_XMIT_FLAGS_NONE	0U
+#define XDP_XMIT_FLUSH		(1U << 0)	/* doorbell signal consumer */
+#define XDP_XMIT_FLAGS_MASK	XDP_XMIT_FLUSH
+
 struct xdp_mem_info {
 	u32 type; /* enum xdp_mem_type, but known size type */
 	u32 id;
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 1fe3fe60508a..037e234056f7 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -232,7 +232,7 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
 		prefetch(xdpf);
 	}
 
-	sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q);
+	sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, 0);
 	if (sent < 0) {
 		err = sent;
 		sent = 0;
diff --git a/net/core/filter.c b/net/core/filter.c
index 28e864777c0f..56e40dafdde7 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3056,7 +3056,7 @@ static int __bpf_tx_xdp(struct net_device *dev,
 	if (unlikely(!xdpf))
 		return -EOVERFLOW;
 
-	sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf);
+	sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf, 0);
 	if (sent <= 0)
 		return sent;
 	dev->netdev_ops->ndo_xdp_flush(dev);