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Date:   Thu, 20 Jul 2023 13:25:03 -0700
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Subject: Re: [PATCH net-next v4 1/2] virtio-net: convert rx mode setting to
 use workqueue
Content-Language: en-US
To:     Jason Wang <jasowang@redhat.com>, mst@redhat.com,
        xuanzhuo@linux.alibaba.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, edumazet@google.com,
        maxime.coquelin@redhat.com, kuba@kernel.org, pabeni@redhat.com,
        davem@davemloft.net
References: <20230720083839.481487-1-jasowang@redhat.com>
 <20230720083839.481487-2-jasowang@redhat.com>
From:   Shannon Nelson <shannon.nelson@amd.com>
In-Reply-To: <20230720083839.481487-2-jasowang@redhat.com>
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On 7/20/23 1:38 AM, Jason Wang wrote:
> 
> This patch convert rx mode setting to be done in a workqueue, this is
> a must for allow to sleep when waiting for the cvq command to
> response since current code is executed under addr spin lock.
> 
> Note that we need to disable and flush the workqueue during freeze,
> this means the rx mode setting is lost after resuming. This is not the
> bug of this patch as we never try to restore rx mode setting during
> resume.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>

> ---
>   drivers/net/virtio_net.c | 55 +++++++++++++++++++++++++++++++++++++---
>   1 file changed, 52 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index d67b36fdba0d..9f3b1d6ac33d 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -274,6 +274,12 @@ struct virtnet_info {
>          /* Work struct for config space updates */
>          struct work_struct config_work;
> 
> +       /* Work struct for setting rx mode */
> +       struct work_struct rx_mode_work;
> +
> +       /* OK to queue work setting RX mode? */
> +       bool rx_mode_work_enabled;
> +
>          /* Does the affinity hint is set for virtqueues? */
>          bool affinity_hint_set;
> 
> @@ -397,6 +403,20 @@ static void disable_delayed_refill(struct virtnet_info *vi)
>          spin_unlock_bh(&vi->refill_lock);
>   }
> 
> +static void enable_rx_mode_work(struct virtnet_info *vi)
> +{
> +       rtnl_lock();
> +       vi->rx_mode_work_enabled = true;
> +       rtnl_unlock();
> +}
> +
> +static void disable_rx_mode_work(struct virtnet_info *vi)
> +{
> +       rtnl_lock();
> +       vi->rx_mode_work_enabled = false;
> +       rtnl_unlock();
> +}
> +
>   static void virtqueue_napi_schedule(struct napi_struct *napi,
>                                      struct virtqueue *vq)
>   {
> @@ -2448,9 +2468,11 @@ static int virtnet_close(struct net_device *dev)
>          return 0;
>   }
> 
> -static void virtnet_set_rx_mode(struct net_device *dev)
> +static void virtnet_rx_mode_work(struct work_struct *work)
>   {
> -       struct virtnet_info *vi = netdev_priv(dev);
> +       struct virtnet_info *vi =
> +               container_of(work, struct virtnet_info, rx_mode_work);
> +       struct net_device *dev = vi->dev;
>          struct scatterlist sg[2];
>          struct virtio_net_ctrl_mac *mac_data;
>          struct netdev_hw_addr *ha;
> @@ -2463,6 +2485,8 @@ static void virtnet_set_rx_mode(struct net_device *dev)
>          if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
>                  return;
> 
> +       rtnl_lock();
> +
>          vi->ctrl->promisc = ((dev->flags & IFF_PROMISC) != 0);
>          vi->ctrl->allmulti = ((dev->flags & IFF_ALLMULTI) != 0);
> 
> @@ -2480,14 +2504,19 @@ static void virtnet_set_rx_mode(struct net_device *dev)
>                  dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
>                           vi->ctrl->allmulti ? "en" : "dis");
> 
> +       netif_addr_lock_bh(dev);
> +
>          uc_count = netdev_uc_count(dev);
>          mc_count = netdev_mc_count(dev);
>          /* MAC filter - use one buffer for both lists */
>          buf = kzalloc(((uc_count + mc_count) * ETH_ALEN) +
>                        (2 * sizeof(mac_data->entries)), GFP_ATOMIC);
>          mac_data = buf;
> -       if (!buf)
> +       if (!buf) {
> +               netif_addr_unlock_bh(dev);
> +               rtnl_unlock();
>                  return;
> +       }
> 
>          sg_init_table(sg, 2);
> 
> @@ -2508,6 +2537,8 @@ static void virtnet_set_rx_mode(struct net_device *dev)
>          netdev_for_each_mc_addr(ha, dev)
>                  memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);
> 
> +       netif_addr_unlock_bh(dev);
> +
>          sg_set_buf(&sg[1], mac_data,
>                     sizeof(mac_data->entries) + (mc_count * ETH_ALEN));
> 
> @@ -2515,9 +2546,19 @@ static void virtnet_set_rx_mode(struct net_device *dev)
>                                    VIRTIO_NET_CTRL_MAC_TABLE_SET, sg))
>                  dev_warn(&dev->dev, "Failed to set MAC filter table.\n");
> 
> +       rtnl_unlock();
> +
>          kfree(buf);
>   }
> 
> +static void virtnet_set_rx_mode(struct net_device *dev)
> +{
> +       struct virtnet_info *vi = netdev_priv(dev);
> +
> +       if (vi->rx_mode_work_enabled)
> +               schedule_work(&vi->rx_mode_work);
> +}
> +
>   static int virtnet_vlan_rx_add_vid(struct net_device *dev,
>                                     __be16 proto, u16 vid)
>   {
> @@ -3286,6 +3327,8 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
> 
>          /* Make sure no work handler is accessing the device */
>          flush_work(&vi->config_work);
> +       disable_rx_mode_work(vi);
> +       flush_work(&vi->rx_mode_work);
> 
>          netif_tx_lock_bh(vi->dev);
>          netif_device_detach(vi->dev);
> @@ -3308,6 +3351,7 @@ static int virtnet_restore_up(struct virtio_device *vdev)
>          virtio_device_ready(vdev);
> 
>          enable_delayed_refill(vi);
> +       enable_rx_mode_work(vi);
> 
>          if (netif_running(vi->dev)) {
>                  err = virtnet_open(vi->dev);
> @@ -4121,6 +4165,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>          vdev->priv = vi;
> 
>          INIT_WORK(&vi->config_work, virtnet_config_changed_work);
> +       INIT_WORK(&vi->rx_mode_work, virtnet_rx_mode_work);
>          spin_lock_init(&vi->refill_lock);
> 
>          if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
> @@ -4229,6 +4274,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>          if (vi->has_rss || vi->has_rss_hash_report)
>                  virtnet_init_default_rss(vi);
> 
> +       enable_rx_mode_work(vi);
> +
>          /* serialize netdev register + virtio_device_ready() with ndo_open() */
>          rtnl_lock();
> 
> @@ -4326,6 +4373,8 @@ static void virtnet_remove(struct virtio_device *vdev)
> 
>          /* Make sure no work handler is accessing the device. */
>          flush_work(&vi->config_work);
> +       disable_rx_mode_work(vi);
> +       flush_work(&vi->rx_mode_work);
> 
>          unregister_netdev(vi->dev);
> 
> --
> 2.39.3
> 
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