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


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