@@ -29,19 +29,39 @@
static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct netdevsim *ns = netdev_priv(dev);
+ unsigned int len = skb->len;
+ struct netdevsim *peer_ns;
+ int ret = NETDEV_TX_OK;
if (!nsim_ipsec_tx(ns, skb))
goto out;
+ rcu_read_lock();
+ peer_ns = rcu_dereference(ns->peer);
+ if (!peer_ns) {
+ dev_kfree_skb(skb);
+ goto out_stats;
+ }
+
+ skb_tx_timestamp(skb);
+ if (unlikely(dev_forward_skb(peer_ns->netdev, skb) == NET_RX_DROP))
+ ret = NET_XMIT_DROP;
+
+out_stats:
+ rcu_read_unlock();
u64_stats_update_begin(&ns->syncp);
- ns->tx_packets++;
- ns->tx_bytes += skb->len;
+ if (ret == NET_XMIT_DROP) {
+ ns->tx_dropped++;
+ } else {
+ ns->tx_packets++;
+ ns->tx_bytes += len;
+ }
u64_stats_update_end(&ns->syncp);
+ return ret;
out:
dev_kfree_skb(skb);
-
- return NETDEV_TX_OK;
+ return ret;
}
static void nsim_set_rx_mode(struct net_device *dev)
@@ -70,6 +90,7 @@ nsim_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
start = u64_stats_fetch_begin(&ns->syncp);
stats->tx_bytes = ns->tx_bytes;
stats->tx_packets = ns->tx_packets;
+ stats->tx_dropped = ns->tx_dropped;
} while (u64_stats_fetch_retry(&ns->syncp, start));
}
@@ -302,7 +323,6 @@ static void nsim_setup(struct net_device *dev)
eth_hw_addr_random(dev);
dev->tx_queue_len = 0;
- dev->flags |= IFF_NOARP;
dev->flags &= ~IFF_MULTICAST;
dev->priv_flags |= IFF_LIVE_ADDR_CHANGE |
IFF_NO_QUEUE;
@@ -98,6 +98,7 @@ struct netdevsim {
u64 tx_packets;
u64 tx_bytes;
+ u64 tx_dropped;
struct u64_stats_sync syncp;
struct nsim_bus_dev *nsim_bus_dev;
Forward skbs sent from one netdevsim port to its connected netdevsim port using dev_forward_skb, in a spirit similar to veth. Add a tx_dropped variable to struct netdevsim, tracking the number of skbs that could not be forwarded using dev_forward_skb(). The xmit() function accessing the peer ptr is protected by an RCU read critical section. The rcu_read_lock() is functionally redundant as since v5.0 all softirqs are implicitly RCU read critical sections; but it is useful for human readers. If another CPU is concurrently in nsim_destroy(), then it will first set the peer ptr to NULL. This does not affect any existing readers that dereferenced a non-NULL peer. Then, in unregister_netdevice(), there is a synchronize_rcu() before the netdev is actually unregistered and freed. This ensures that any readers i.e. xmit() that got a non-NULL peer will complete before the netdev is freed. Any readers after the RCU_INIT_POINTER() but before synchronize_rcu() will dereference NULL, making it safe. The codepath to nsim_destroy() and nsim_create() takes both the newly added nsim_dev_list_lock and rtnl_lock. This makes it safe with concurrent calls to linking two netdevsims together. Signed-off-by: David Wei <dw@davidwei.uk> --- drivers/net/netdevsim/netdev.c | 30 +++++++++++++++++++++++++----- drivers/net/netdevsim/netdevsim.h | 1 + 2 files changed, 26 insertions(+), 5 deletions(-)