[PATCH 5.4 31/60] virtio_net: fix xdp_rxq_info bug after suspend/resume

Greg Kroah-Hartman
2022-06-27T11:33:53Z

From: Stephan Gerhold <stephan.gerhold@kernkonzept.com>

[ Upstream commit 8af52fe9fd3bf5e7478da99193c0632276e1dfce ]

The following sequence currently causes a driver bug warning
when using virtio_net:

# ip link set eth0 up
# echo mem > /sys/power/state (or e.g. # rtcwake -s 10 -m mem)
<resume>
# ip link set eth0 down

Missing register, driver bug
WARNING: CPU: 0 PID: 375 at net/core/xdp.c:138 xdp_rxq_info_unreg+0x58/0x60
Call trace:
xdp_rxq_info_unreg+0x58/0x60
virtnet_close+0x58/0xac
__dev_close_many+0xac/0x140
__dev_change_flags+0xd8/0x210
dev_change_flags+0x24/0x64
do_setlink+0x230/0xdd0
...

This happens because virtnet_freeze() frees the receive_queue
completely (including struct xdp_rxq_info) but does not call
xdp_rxq_info_unreg(). Similarly, virtnet_restore() sets up the
receive_queue again but does not call xdp_rxq_info_reg().

Actually, parts of virtnet_freeze_down() and virtnet_restore_up()
are almost identical to virtnet_close() and virtnet_open(): only
the calls to xdp_rxq_info_(un)reg() are missing. This means that
we can fix this easily and avoid such problems in the future by
just calling virtnet_close()/open() from the freeze/restore handlers.

Aside from adding the missing xdp_rxq_info calls the only difference
is that the refill work is only cancelled if netif_running(). However,
this should not make any functional difference since the refill work
should only be active if the network interface is actually up.

Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220621114845.3650258-1-stephan.gerhold@kernkonzept.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/virtio_net.c | 25 ++++++-------------------
1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 37c2cecd1e50..f4c03518d7d2 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2393,7 +2393,6 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
static void virtnet_freeze_down(struct virtio_device *vdev)
{
struct virtnet_info *vi = vdev->priv;
- int i;

/* Make sure no work handler is accessing the device */
flush_work(&vi->config_work);
@@ -2401,14 +2400,8 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
netif_tx_lock_bh(vi->dev);
netif_device_detach(vi->dev);
netif_tx_unlock_bh(vi->dev);
- cancel_delayed_work_sync(&vi->refill);
-
- if (netif_running(vi->dev)) {
- for (i = 0; i < vi->max_queue_pairs; i++) {
- napi_disable(&vi->rq[i].napi);
- virtnet_napi_tx_disable(&vi->sq[i].napi);
- }
- }
+ if (netif_running(vi->dev))
+ virtnet_close(vi->dev);
}

static int init_vqs(struct virtnet_info *vi);
@@ -2416,7 +2409,7 @@ static int init_vqs(struct virtnet_info *vi);
static int virtnet_restore_up(struct virtio_device *vdev)
{
struct virtnet_info *vi = vdev->priv;
- int err, i;
+ int err;

err = init_vqs(vi);
if (err)
@@ -2425,15 +2418,9 @@ static int virtnet_restore_up(struct virtio_device *vdev)
virtio_device_ready(vdev);

if (netif_running(vi->dev)) {
- for (i = 0; i < vi->curr_queue_pairs; i++)
- if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
- schedule_delayed_work(&vi->refill, 0);
-
- for (i = 0; i < vi->max_queue_pairs; i++) {
- virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
- virtnet_napi_tx_enable(vi, vi->sq[i].vq,
- &vi->sq[i].napi);
- }
+ err = virtnet_open(vi->dev);
+ if (err)
+ return err;
}

netif_tx_lock_bh(vi->dev);
--
2.35.1