Jason Wang
2023-May-24 08:18 UTC
[PATCH V3 net-next 0/2] virtio-net: don't busy poll for cvq command
Hi all: The code used to busy poll for cvq command which turns out to have several side effects: 1) infinite poll for buggy devices 2) bad interaction with scheduler So this series tries to use cond_resched() in the waiting loop. Before doing this we need first make sure the cvq command is not executed in atomic environment, so we need first convert rx mode handling to a workqueue. Please review. Thanks Changes since V2: - Don't use interrupt but cond_resched() Changes since V1: - use RTNL to synchronize rx mode worker - use completion for simplicity - don't try to harden CVQ command Changes since RFC: - switch to use BAD_RING in virtio_break_device() - check virtqueue_is_broken() after being woken up - use more_used() instead of virtqueue_get_buf() to allow caller to get buffers afterwards - break the virtio-net device when timeout - get buffer manually since the virtio core check more_used() instead Jason Wang (2): virtio-net: convert rx mode setting to use workqueue virtio-net: add cond_resched() to the command waiting loop drivers/net/virtio_net.c | 59 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 55 insertions(+), 4 deletions(-) -- 2.25.1
Jason Wang
2023-May-24 08:18 UTC
[PATCH V3 net-next 1/2] virtio-net: convert rx mode setting to use workqueue
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. Signed-off-by: Jason Wang <jasowang at redhat.com> --- Changes since V1: - use RTNL to synchronize rx mode worker --- 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 56ca1d270304..5d2f1da4eaa0 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -265,6 +265,12 @@ struct virtnet_info { /* Work struct for config space updates */ struct work_struct config_work; + /* Work struct for config rx mode */ + struct work_struct rx_mode_work; + + /* Is rx mode work enabled? */ + bool rx_mode_work_enabled; + /* Does the affinity hint is set for virtqueues? */ bool affinity_hint_set; @@ -388,6 +394,20 @@ 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) { @@ -2341,9 +2361,11 @@ 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; @@ -2356,6 +2378,8 @@ 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); @@ -2373,14 +2397,19 @@ 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); @@ -2401,6 +2430,8 @@ 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)); @@ -2408,9 +2439,19 @@ 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) { @@ -3181,6 +3222,8 @@ 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); @@ -3203,6 +3246,7 @@ 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); @@ -4002,6 +4046,7 @@ 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)) { @@ -4110,6 +4155,8 @@ 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(); @@ -4207,6 +4254,8 @@ 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); -- 2.25.1
Jason Wang
2023-May-24 08:18 UTC
[PATCH V3 net-next 2/2] virtio-net: add cond_resched() to the command waiting loop
Adding cond_resched() to the command waiting loop for a better co-operation with the scheduler. This allows to give CPU a breath to run other task(workqueue) instead of busy looping when preemption is not allowed on a device whose CVQ might be slow. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/net/virtio_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 5d2f1da4eaa0..de498dbbf0d4 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2207,8 +2207,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, * into the hypervisor, so the request should be handled immediately. */ while (!virtqueue_get_buf(vi->cvq, &tmp) && - !virtqueue_is_broken(vi->cvq)) + !virtqueue_is_broken(vi->cvq)) { + cond_resched(); cpu_relax(); + } return vi->ctrl->status == VIRTIO_NET_OK; } -- 2.25.1
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