From f207c10d982388fa42710922ad1c0c9d3ba9a87b Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 22 Sep 2016 16:56:33 -0700 Subject: [PATCH] hv_netvsc: use RCU to protect vf_netdev The vf_netdev pointer in the netvsc device context can simply be protected by RCU because network device destruction is already RCU synchronized. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- drivers/net/hyperv/hyperv_net.h | 2 +- drivers/net/hyperv/netvsc_drv.c | 29 +++++++++++++++-------------- 2 files changed, 16 insertions(+), 15 deletions(-) diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h index 284b97b6b258..6b7948764443 100644 --- a/drivers/net/hyperv/hyperv_net.h +++ b/drivers/net/hyperv/hyperv_net.h @@ -695,7 +695,7 @@ struct net_device_context { bool start_remove; /* State to manage the associated VF interface. */ - struct net_device *vf_netdev; + struct net_device __rcu *vf_netdev; bool vf_inject; atomic_t vf_use_cnt; /* 1: allocated, serial number is valid. 0: not allocated */ diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 87682198ff73..dde17c0faf9f 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -667,8 +667,8 @@ int netvsc_recv_callback(struct hv_device *device_obj, { struct net_device *net = hv_get_drvdata(device_obj); struct net_device_context *net_device_ctx = netdev_priv(net); + struct net_device *vf_netdev; struct sk_buff *skb; - struct sk_buff *vf_skb; struct netvsc_stats *rx_stats; u32 bytes_recvd = packet->total_data_buflen; int ret = 0; @@ -676,9 +676,12 @@ int netvsc_recv_callback(struct hv_device *device_obj, if (!net || net->reg_state != NETREG_REGISTERED) return NVSP_STAT_FAIL; - if (READ_ONCE(net_device_ctx->vf_inject)) { + vf_netdev = rcu_dereference(net_device_ctx->vf_netdev); + if (vf_netdev) { + struct sk_buff *vf_skb; + atomic_inc(&net_device_ctx->vf_use_cnt); - if (!READ_ONCE(net_device_ctx->vf_inject)) { + if (!net_device_ctx->vf_inject) { /* * We raced; just move on. */ @@ -694,13 +697,12 @@ int netvsc_recv_callback(struct hv_device *device_obj, * the host). Deliver these via the VF interface * in the guest. */ - vf_skb = netvsc_alloc_recv_skb(net_device_ctx->vf_netdev, + vf_skb = netvsc_alloc_recv_skb(vf_netdev, packet, csum_info, *data, vlan_tci); if (vf_skb != NULL) { - ++net_device_ctx->vf_netdev->stats.rx_packets; - net_device_ctx->vf_netdev->stats.rx_bytes += - bytes_recvd; + ++vf_netdev->stats.rx_packets; + vf_netdev->stats.rx_bytes += bytes_recvd; netif_receive_skb(vf_skb); } else { ++net->stats.rx_dropped; @@ -1232,7 +1234,7 @@ static struct net_device *get_netvsc_bymac(const u8 *mac) return NULL; } -static struct net_device *get_netvsc_byref(const struct net_device *vf_netdev) +static struct net_device *get_netvsc_byref(struct net_device *vf_netdev) { struct net_device *dev; @@ -1248,7 +1250,7 @@ static struct net_device *get_netvsc_byref(const struct net_device *vf_netdev) if (net_device_ctx->nvdev == NULL) continue; /* device is removed */ - if (net_device_ctx->vf_netdev == vf_netdev) + if (rtnl_dereference(net_device_ctx->vf_netdev) == vf_netdev) return dev; /* a match */ } @@ -1275,7 +1277,7 @@ static int netvsc_register_vf(struct net_device *vf_netdev) net_device_ctx = netdev_priv(ndev); netvsc_dev = net_device_ctx->nvdev; - if (!netvsc_dev || net_device_ctx->vf_netdev) + if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev)) return NOTIFY_DONE; netdev_info(ndev, "VF registering: %s\n", vf_netdev->name); @@ -1285,7 +1287,7 @@ static int netvsc_register_vf(struct net_device *vf_netdev) try_module_get(THIS_MODULE); dev_hold(vf_netdev); - net_device_ctx->vf_netdev = vf_netdev; + rcu_assign_pointer(net_device_ctx->vf_netdev, vf_netdev); return NOTIFY_OK; } @@ -1379,7 +1381,8 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev) netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name); netvsc_inject_disable(net_device_ctx); - net_device_ctx->vf_netdev = NULL; + + RCU_INIT_POINTER(net_device_ctx->vf_netdev, NULL); dev_put(vf_netdev); module_put(THIS_MODULE); return NOTIFY_OK; @@ -1433,8 +1436,6 @@ static int netvsc_probe(struct hv_device *dev, INIT_LIST_HEAD(&net_device_ctx->reconfig_events); atomic_set(&net_device_ctx->vf_use_cnt, 0); - net_device_ctx->vf_netdev = NULL; - net_device_ctx->vf_inject = false; net->netdev_ops = &device_ops; -- 2.20.1