netdev - [PATCH net v4] virtio_net: Fix error unwinding of XDP initialization

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Date: Mon, 8 May 2023 18:27:08 -0400
From: Feng Liu <feliu@...dia.com>
To: <virtualization@...ts.linux-foundation.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>
CC: Jason Wang <jasowang@...hat.com>, "Michael S . Tsirkin" <mst@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Simon Horman
	<simon.horman@...igine.com>, Bodong Wang <bodong@...dia.com>, Feng Liu
	<feliu@...dia.com>, Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net v4] virtio_net: Fix error unwinding of XDP initialization

When initializing XDP in virtnet_open(), some rq xdp initialization
may hit an error causing net device open failed. However, previous
rqs have already initialized XDP and enabled NAPI, which is not the
expected behavior. Need to roll back the previous rq initialization
to avoid leaks in error unwinding of init code.

Also extract helper functions of disable and enable queue pairs.
Use newly introduced disable helper function in error unwinding and
virtnet_close. Use enable helper function in virtnet_open.

Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
Signed-off-by: Feng Liu <feliu@...dia.com>
Reviewed-by: Jiri Pirko <jiri@...dia.com>
---

v3 -> v4
feedbacks from Jiri Pirko
- Add symmetric helper function virtnet_enable_qp to enable queues.
- Error handle:  cleanup current queue pair in virtnet_enable_qp,
  and complete the reset queue pairs cleanup in virtnet_open.
- Fix coding style.
feedbacks from Parav Pandit
- Remove redundant debug message and white space.

v2 -> v3
feedbacks from Michael S. Tsirkin
- Remove redundant comment.

v1 -> v2
feedbacks from Michael S. Tsirkin
- squash two patches together.

---
 drivers/net/virtio_net.c | 58 ++++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 17 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8d8038538fc4..df7c08048fa7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1868,6 +1868,38 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
 	return received;
 }
 
+static void virtnet_disable_qp(struct virtnet_info *vi, int qp_index)
+{
+	virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
+	napi_disable(&vi->rq[qp_index].napi);
+	xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
+}
+
+static int virtnet_enable_qp(struct virtnet_info *vi, int qp_index)
+{
+	struct net_device *dev = vi->dev;
+	int err;
+
+	err = xdp_rxq_info_reg(&vi->rq[qp_index].xdp_rxq, dev, qp_index,
+			       vi->rq[qp_index].napi.napi_id);
+	if (err < 0)
+		return err;
+
+	err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
+					 MEM_TYPE_PAGE_SHARED, NULL);
+	if (err < 0)
+		goto err_xdp_reg_mem_model;
+
+	virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
+	virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
+
+	return 0;
+
+err_xdp_reg_mem_model:
+	xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
+	return err;
+}
+
 static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
@@ -1881,22 +1913,17 @@ static int virtnet_open(struct net_device *dev)
 			if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
 				schedule_delayed_work(&vi->refill, 0);
 
-		err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i, vi->rq[i].napi.napi_id);
+		err = virtnet_enable_qp(vi, i);
 		if (err < 0)
-			return err;
-
-		err = xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
-						 MEM_TYPE_PAGE_SHARED, NULL);
-		if (err < 0) {
-			xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
-			return err;
-		}
-
-		virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
-		virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
+			goto err_enable_qp;
 	}
 
 	return 0;
+
+err_enable_qp:
+	for (i--; i >= 0; i--)
+		virtnet_disable_qp(vi, i);
+	return err;
 }
 
 static int virtnet_poll_tx(struct napi_struct *napi, int budget)
@@ -2305,11 +2332,8 @@ static int virtnet_close(struct net_device *dev)
 	/* Make sure refill_work doesn't re-enable napi! */
 	cancel_delayed_work_sync(&vi->refill);
 
-	for (i = 0; i < vi->max_queue_pairs; i++) {
-		virtnet_napi_tx_disable(&vi->sq[i].napi);
-		napi_disable(&vi->rq[i].napi);
-		xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
-	}
+	for (i = 0; i < vi->max_queue_pairs; i++)
+		virtnet_disable_qp(vi, i);
 
 	return 0;
 }
-- 
2.37.1 (Apple Git-137.1)