[PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

[PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

[David Wei]

This patchset adds the ability to link two netdevsim ports together and
forward skbs between them, similar to veth. The goal is to use netdevsim
for testing features e.g. zero copy Rx using io_uring.

This feature was tested locally on QEMU, and a selftest is included.

---
v7->v8:
- fix not dereferencing RCU ptr using rcu_dereference()
- remove unused variables in selftest

v6->v7:
- change link syntax to netnsid:ifidx
- replace dev_get_by_index() with __dev_get_by_index()
- check for NULL peer when linking
- add a sysfs attribute for unlinking
- only update Tx stats if not dropped
- update selftest

v5->v6:
- reworked to link two netdevsims using sysfs attribute on the bus
  device instead of debugfs due to deadlock possibility if a netdevsim
  is removed during linking
- removed unnecessary patch maintaining a list of probed nsim_devs
- updated selftest

v4->v5:
- reduce nsim_dev_list_lock critical section
- fixed missing mutex unlock during unwind ladder
- rework nsim_dev_peer_write synchronization to take devlink lock as
  well as rtnl_lock
- return err msgs to user during linking if port doesn't exist or
  linking to self
- update tx stats outside of RCU lock

v3->v4:
- maintain a mutex protected list of probed nsim_devs instead of using
  nsim_bus_dev
- fixed synchronization issues by taking rtnl_lock
- track tx_dropped skbs

v2->v3:
- take lock when traversing nsim_bus_dev_list
- take device ref when getting a nsim_bus_dev
- return 0 if nsim_dev_peer_read cannot find the port
- address code formatting
- do not hard code values in selftests
- add Makefile for selftests

v1->v2:
- renamed debugfs file from "link" to "peer"
- replaced strstep() with sscanf() for consistency
- increased char[] buf sz to 22 for copying id + port from user
- added err msg w/ expected fmt when linking as a hint to user
- prevent linking port to itself
- protect peer ptr using RCU

David Wei (4):
  netdevsim: allow two netdevsim ports to be connected
  netdevsim: forward skbs from one connected port to another
  netdevsim: add selftest for forwarding skb between connected ports
  netdevsim: add Makefile for selftests

 MAINTAINERS                                   |   1 +
 drivers/net/netdevsim/bus.c                   | 130 ++++++++++++++++++
 drivers/net/netdevsim/netdev.c                |  39 +++++-
 drivers/net/netdevsim/netdevsim.h             |   3 +
 .../selftests/drivers/net/netdevsim/Makefile  |  18 +++
 .../selftests/drivers/net/netdevsim/peer.sh   | 125 +++++++++++++++++
 6 files changed, 311 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/drivers/net/netdevsim/Makefile
 create mode 100755 tools/testing/selftests/drivers/net/netdevsim/peer.sh

-- 
2.39.3

[PATCH net-next v8 1/4] netdevsim: allow two netdevsim ports to be connected

[David Wei]

Add two netdevsim bus attribute to sysfs:
/sys/bus/netdevsim/link_device
/sys/bus/netdevsim/unlink_device

Writing "A M B N" to link_device will link netdevsim M in netnsid A with
netdevsim N in netnsid B.

Writing "A M" to unlink_device will unlink netdevsim M in netnsid A from
its peer, if any.

rtnl_lock is taken to ensure nothing changes during the linking.

Signed-off-by: David Wei <dw@davidwei.uk>
---
 drivers/net/netdevsim/bus.c       | 132 ++++++++++++++++++++++++++++++
 drivers/net/netdevsim/netdev.c    |  11 +++
 drivers/net/netdevsim/netdevsim.h |   2 +
 3 files changed, 145 insertions(+)

diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
index bcbc1e19edde..57e28801bb51 100644
--- a/drivers/net/netdevsim/bus.c
+++ b/drivers/net/netdevsim/bus.c
@@ -232,9 +232,141 @@ del_device_store(const struct bus_type *bus, const char *buf, size_t count)
 }
 static BUS_ATTR_WO(del_device);
 
+static ssize_t link_device_store(const struct bus_type *bus, const char *buf, size_t count)
+{
+	unsigned int netnsid_a, netnsid_b, ifidx_a, ifidx_b;
+	struct netdevsim *nsim_a, *nsim_b, *peer;
+	struct net_device *dev_a, *dev_b;
+	struct net *ns_a, *ns_b;
+	int err;
+
+	err = sscanf(buf, "%u:%u %u:%u", &netnsid_a, &ifidx_a, &netnsid_b, &ifidx_b);
+	if (err != 4) {
+		pr_err("Format for linking two devices is \"netnsid_a:ifidx_a netnsid_b:ifidx_b\" (uint uint unit uint).\n");
+		return -EINVAL;
+	}
+
+	err = -EINVAL;
+	rtnl_lock();
+	ns_a = get_net_ns_by_id(current->nsproxy->net_ns, netnsid_a);
+	if (!ns_a) {
+		pr_err("Could not find netns with id: %u\n", netnsid_a);
+		goto out_unlock_rtnl;
+	}
+
+	dev_a = __dev_get_by_index(ns_a, ifidx_a);
+	if (!dev_a) {
+		pr_err("Could not find device with ifindex %u in netnsid %u\n", ifidx_a, netnsid_a);
+		goto out_put_netns_a;
+	}
+
+	if (!netdev_is_nsim(dev_a)) {
+		pr_err("Device with ifindex %u in netnsid %u is not a netdevsim\n", ifidx_a, netnsid_a);
+		goto out_put_netns_a;
+	}
+
+	ns_b = get_net_ns_by_id(current->nsproxy->net_ns, netnsid_b);
+	if (!ns_b) {
+		pr_err("Could not find netns with id: %u\n", netnsid_b);
+		goto out_put_netns_a;
+	}
+
+	dev_b = __dev_get_by_index(ns_b, ifidx_b);
+	if (!dev_b) {
+		pr_err("Could not find device with ifindex %u in netnsid %u\n", ifidx_b, netnsid_b);
+		goto out_put_netns_b;
+	}
+
+	if (!netdev_is_nsim(dev_b)) {
+		pr_err("Device with ifindex %u in netnsid %u is not a netdevsim\n", ifidx_b, netnsid_b);
+		goto out_put_netns_b;
+	}
+
+	err = 0;
+	nsim_a = netdev_priv(dev_a);
+	peer = rtnl_dereference(nsim_a->peer);
+	if (peer) {
+		pr_err("Netdevsim %u:%u is already linked\n", netnsid_a, ifidx_a);
+		goto out_put_netns_b;
+	}
+
+	nsim_b = netdev_priv(dev_b);
+	peer = rtnl_dereference(nsim_b->peer);
+	if (peer) {
+		pr_err("Netdevsim %u:%u is already linked\n", netnsid_b, ifidx_b);
+		goto out_put_netns_b;
+	}
+
+	rcu_assign_pointer(nsim_a->peer, nsim_b);
+	rcu_assign_pointer(nsim_b->peer, nsim_a);
+
+out_put_netns_b:
+	put_net(ns_b);
+out_put_netns_a:
+	put_net(ns_a);
+out_unlock_rtnl:
+	rtnl_unlock();
+
+	return !err ? count : err;
+}
+static BUS_ATTR_WO(link_device);
+
+static ssize_t unlink_device_store(const struct bus_type *bus, const char *buf, size_t count)
+{
+	struct netdevsim *nsim, *peer;
+	unsigned int netnsid, ifidx;
+	struct net_device *dev;
+	struct net *ns;
+	int err;
+
+	err = sscanf(buf, "%u:%u", &netnsid, &ifidx);
+	if (err != 2) {
+		pr_err("Format for unlinking a device is \"netnsid:ifidx\" (uint uint).\n");
+		return -EINVAL;
+	}
+
+	err = -EINVAL;
+	rtnl_lock();
+	ns = get_net_ns_by_id(current->nsproxy->net_ns, netnsid);
+	if (!ns) {
+		pr_err("Could not find netns with id: %u\n", netnsid);
+		goto out_unlock_rtnl;
+	}
+
+	dev = __dev_get_by_index(ns, ifidx);
+	if (!dev) {
+		pr_err("Could not find device with ifindex %u in netnsid %u\n", ifidx, netnsid);
+		goto out_put_netns;
+	}
+
+	if (!netdev_is_nsim(dev)) {
+		pr_err("Device with ifindex %u in netnsid %u is not a netdevsim\n", ifidx, netnsid);
+		goto out_put_netns;
+	}
+
+	err = 0;
+	nsim = netdev_priv(dev);
+	peer = rtnl_dereference(nsim->peer);
+	if (!peer)
+		goto out_put_netns;
+
+	RCU_INIT_POINTER(nsim->peer, NULL);
+	RCU_INIT_POINTER(peer->peer, NULL);
+
+out_put_netns:
+	put_net(ns);
+out_unlock_rtnl:
+	rtnl_unlock();
+
+	return !err ? count : err;
+}
+static BUS_ATTR_WO(unlink_device);
+
 static struct attribute *nsim_bus_attrs[] = {
 	&bus_attr_new_device.attr,
 	&bus_attr_del_device.attr,
+	&bus_attr_link_device.attr,
+	&bus_attr_unlink_device.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(nsim_bus);
diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index 77e8250282a5..57883773e4fb 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -333,6 +333,7 @@ static int nsim_init_netdevsim(struct netdevsim *ns)
 		goto err_phc_destroy;
 
 	rtnl_lock();
+	RCU_INIT_POINTER(ns->peer, NULL);
 	err = nsim_bpf_init(ns);
 	if (err)
 		goto err_utn_destroy;
@@ -413,8 +414,13 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
 void nsim_destroy(struct netdevsim *ns)
 {
 	struct net_device *dev = ns->netdev;
+	struct netdevsim *peer;
 
 	rtnl_lock();
+	peer = rtnl_dereference(ns->peer);
+	if (peer)
+		RCU_INIT_POINTER(peer->peer, NULL);
+	RCU_INIT_POINTER(ns->peer, NULL);
 	unregister_netdevice(dev);
 	if (nsim_dev_port_is_pf(ns->nsim_dev_port)) {
 		nsim_macsec_teardown(ns);
@@ -427,6 +433,11 @@ void nsim_destroy(struct netdevsim *ns)
 	free_netdev(dev);
 }
 
+bool netdev_is_nsim(struct net_device *dev)
+{
+	return dev->netdev_ops == &nsim_netdev_ops;
+}
+
 static int nsim_validate(struct nlattr *tb[], struct nlattr *data[],
 			 struct netlink_ext_ack *extack)
 {
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 028c825b86db..c8b45b0d955e 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -125,11 +125,13 @@ struct netdevsim {
 	} udp_ports;
 
 	struct nsim_ethtool ethtool;
+	struct netdevsim __rcu *peer;
 };
 
 struct netdevsim *
 nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port);
 void nsim_destroy(struct netdevsim *ns);
+bool netdev_is_nsim(struct net_device *dev);
 
 void nsim_ethtool_init(struct netdevsim *ns);
 
-- 
2.39.3

[PATCH net-next v8 2/4] netdevsim: forward skbs from one connected port to another

[David Wei]

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    | 28 +++++++++++++++++++++++-----
 drivers/net/netdevsim/netdevsim.h |  1 +
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index 57883773e4fb..fd6bf789ff70 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -29,19 +29,37 @@
 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)
+		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 +88,7 @@ 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 +321,6 @@ 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;
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index c8b45b0d955e..553c4b9b4f63 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -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;
-- 
2.39.3

[PATCH net-next v8 3/4] netdevsim: add selftest for forwarding skb between connected ports

[David Wei]

Connect two netdevsim ports in different namespaces together, then send
packets between them using socat.

Signed-off-by: David Wei <dw@davidwei.uk>
---
 .../selftests/drivers/net/netdevsim/peer.sh   | 125 ++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100755 tools/testing/selftests/drivers/net/netdevsim/peer.sh

diff --git a/tools/testing/selftests/drivers/net/netdevsim/peer.sh b/tools/testing/selftests/drivers/net/netdevsim/peer.sh
new file mode 100755
index 000000000000..9d232fc50d69
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netdevsim/peer.sh
@@ -0,0 +1,125 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+
+NSIM_DEV_1_ID=$((RANDOM % 1024))
+NSIM_DEV_1_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_DEV_1_ID
+NSIM_DEV_2_ID=$((RANDOM % 1024))
+NSIM_DEV_2_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_DEV_2_ID
+
+NSIM_DEV_SYS_NEW=/sys/bus/netdevsim/new_device
+NSIM_DEV_SYS_DEL=/sys/bus/netdevsim/del_device
+NSIM_DEV_SYS_LINK=/sys/bus/netdevsim/link_device
+NSIM_DEV_SYS_UNLINK=/sys/bus/netdevsim/unlink_device
+
+socat_check()
+{
+	if [ ! -x "$(command -v socat)" ]; then
+		echo "socat command not found. Skipping test"
+		return 1
+	fi
+
+	return 0
+}
+
+setup_ns()
+{
+	set -e
+	ip netns add nssv
+	ip netns add nscl
+
+	NSIM_DEV_1_NAME=$(find $NSIM_DEV_1_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_DEV_1_SYS/net -exec basename {} \;)
+	NSIM_DEV_2_NAME=$(find $NSIM_DEV_2_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_DEV_2_SYS/net -exec basename {} \;)
+
+	ip link set $NSIM_DEV_1_NAME netns nssv
+	ip link set $NSIM_DEV_2_NAME netns nscl
+
+	ip netns exec nssv ip addr add '192.168.1.1/24' dev $NSIM_DEV_1_NAME
+	ip netns exec nscl ip addr add '192.168.1.2/24' dev $NSIM_DEV_2_NAME
+
+	ip netns exec nssv ip link set dev $NSIM_DEV_1_NAME up
+	ip netns exec nscl ip link set dev $NSIM_DEV_2_NAME up
+	set +e
+}
+
+cleanup_ns()
+{
+	ip netns del nscl
+	ip netns del nssv
+}
+
+###
+### Code start
+###
+
+modprobe netdevsim
+
+# linking
+
+echo $NSIM_DEV_1_ID > $NSIM_DEV_SYS_NEW
+echo $NSIM_DEV_2_ID > $NSIM_DEV_SYS_NEW
+
+setup_ns
+
+NSIM_DEV_1_NETNSID=$(ip netns list-id | grep nssv | awk '{print $2}')
+NSIM_DEV_1_IFIDX=$(ip netns exec nssv cat /sys/class/net/$NSIM_DEV_1_NAME/ifindex)
+
+NSIM_DEV_2_NETNSID=$(ip netns list-id | grep nscl | awk '{print $2}')
+NSIM_DEV_2_IFIDX=$(ip netns exec nscl cat /sys/class/net/$NSIM_DEV_2_NAME/ifindex)
+
+echo "$NSIM_DEV_1_NETNSID:$NSIM_DEV_1_IFIDX $NSIM_DEV_2_NETNSID:20" > $NSIM_DEV_SYS_LINK 2>/dev/null
+if [ $? -eq 0 ]; then
+	echo "linking with non-existent netdevsim should fail"
+	exit 1
+fi
+
+echo "$NSIM_DEV_1_NETNSID:$NSIM_DEV_1_IFIDX 20:$NSIM_DEV_2_IFIDX" > $NSIM_DEV_SYS_LINK 2>/dev/null
+if [ $? -eq 0 ]; then
+	echo "linking with non-existent netnsid should fail"
+	exit 1
+fi
+
+echo "$NSIM_DEV_1_NETNSID:$NSIM_DEV_1_IFIDX $NSIM_DEV_2_NETNSID:$NSIM_DEV_2_IFIDX" > $NSIM_DEV_SYS_LINK
+if [ $? -ne 0 ]; then
+	echo "linking netdevsim1 with netdevsim2 should succeed"
+	exit 1
+fi
+
+# argument error checking
+
+echo "$NSIM_DEV_1_NETNSID:$NSIM_DEV_1_IFIDX $NSIM_DEV_2_NETNSID:a" > $NSIM_DEV_SYS_LINK 2>/dev/null
+if [ $? -eq 0 ]; then
+	echo "invalid arg should fail"
+	exit 1
+fi
+
+# send/recv packets
+
+socat_check || exit 4
+
+tmp_file=$(mktemp)
+ip netns exec nssv socat TCP-LISTEN:1234,fork $tmp_file &
+pid=$!
+res=0
+
+echo "HI" | ip netns exec nscl socat STDIN TCP:192.168.1.1:1234
+
+count=$(cat $tmp_file | wc -c)
+if [[ $count -ne 3 ]]; then
+	echo "expected 3 bytes, got $count"
+	res=1
+fi
+
+echo "$NSIM_DEV_1_NETNSID:$NSIM_DEV_1_IFIDX" > $NSIM_DEV_SYS_UNLINK
+
+echo $NSIM_DEV_2_ID > $NSIM_DEV_SYS_DEL
+
+kill $pid
+echo $NSIM_DEV_1_ID > $NSIM_DEV_SYS_DEL
+
+cleanup_ns
+
+modprobe -r netdevsim
+
+exit $res
-- 
2.39.3

[PATCH net-next v8 4/4] netdevsim: add Makefile for selftests

[David Wei]

Add a Makefile for netdevsim selftests and add selftests path to
MAINTAINERS

Signed-off-by: David Wei <dw@davidwei.uk>
---
 MAINTAINERS                                    |  1 +
 .../selftests/drivers/net/netdevsim/Makefile   | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 tools/testing/selftests/drivers/net/netdevsim/Makefile

diff --git a/MAINTAINERS b/MAINTAINERS
index 92152ac346c8..562af3dfd2d0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15082,6 +15082,7 @@ NETDEVSIM
 M:	Jakub Kicinski <kuba@kernel.org>
 S:	Maintained
 F:	drivers/net/netdevsim/*
+F:	tools/testing/selftests/drivers/net/netdevsim/*
 
 NETEM NETWORK EMULATOR
 M:	Stephen Hemminger <stephen@networkplumber.org>
diff --git a/tools/testing/selftests/drivers/net/netdevsim/Makefile b/tools/testing/selftests/drivers/net/netdevsim/Makefile
new file mode 100644
index 000000000000..5bace0b7fb57
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netdevsim/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0+ OR MIT
+
+TEST_PROGS = devlink.sh \
+	devlink_in_netns.sh \
+	devlink_trap.sh \
+	ethtool-coalesce.sh \
+	ethtool-fec.sh \
+	ethtool-pause.sh \
+	ethtool-ring.sh \
+	fib.sh \
+	hw_stats_l3.sh \
+	nexthop.sh \
+	peer.sh \
+	psample.sh \
+	tc-mq-visibility.sh \
+	udp_tunnel_nic.sh \
+
+include ../../../lib.mk
-- 
2.39.3

Re: [PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

[Jakub Kicinski]

On Tue, 30 Jan 2024 13:46:16 -0800 David Wei wrote:
> [PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

There's only 4 patches here, you'll need to repost because you promised
patchwork 5 by saying 0/5 :(

Re: [PATCH net-next v8 1/4] netdevsim: allow two netdevsim ports to be connected

[Jakub Kicinski]

On Tue, 30 Jan 2024 13:46:17 -0800 David Wei wrote:
> +	err = -EINVAL;
> +	rtnl_lock();
> +	ns_a = get_net_ns_by_id(current->nsproxy->net_ns, netnsid_a);

I think we should support local netns, i.e. the one which we are
currently in. But by definition it has no id. How about we make the
netns id signed and make -1 mean "use current->nsproxy->net_ns
directly"?

Also you can look up the netns before taking rtnl_lock, they are 
not protected by rtnl_lock.

> +	if (!ns_a) {
> +		pr_err("Could not find netns with id: %u\n", netnsid_a);
> +		goto out_unlock_rtnl;
> +	}
> +
> +	dev_a = __dev_get_by_index(ns_a, ifidx_a);
> +	if (!dev_a) {
> +		pr_err("Could not find device with ifindex %u in netnsid %u\n", ifidx_a, netnsid_a);
> +		goto out_put_netns_a;
> +	}
> +
> +	if (!netdev_is_nsim(dev_a)) {
> +		pr_err("Device with ifindex %u in netnsid %u is not a netdevsim\n", ifidx_a, netnsid_a);
> +		goto out_put_netns_a;
> +	}
> +
> +	ns_b = get_net_ns_by_id(current->nsproxy->net_ns, netnsid_b);
> +	if (!ns_b) {
> +		pr_err("Could not find netns with id: %u\n", netnsid_b);
> +		goto out_put_netns_a;
> +	}
> +
> +	dev_b = __dev_get_by_index(ns_b, ifidx_b);
> +	if (!dev_b) {
> +		pr_err("Could not find device with ifindex %u in netnsid %u\n", ifidx_b, netnsid_b);
> +		goto out_put_netns_b;
> +	}
> +
> +	if (!netdev_is_nsim(dev_b)) {
> +		pr_err("Device with ifindex %u in netnsid %u is not a netdevsim\n", ifidx_b, netnsid_b);
> +		goto out_put_netns_b;
> +	}

You're missing if dev_a == dev_b return goto out..; ?
Actually I can't think of a reason why looping would explode.
Could you test it and if it indeed doesn't splat add a comment
here that loops are okay?

> +	err = 0;
> +	nsim_a = netdev_priv(dev_a);
> +	peer = rtnl_dereference(nsim_a->peer);
> +	if (peer) {
> +		pr_err("Netdevsim %u:%u is already linked\n", netnsid_a, ifidx_a);
> +		goto out_put_netns_b;
> +	}
> +
> +	nsim_b = netdev_priv(dev_b);
> +	peer = rtnl_dereference(nsim_b->peer);
> +	if (peer) {
> +		pr_err("Netdevsim %u:%u is already linked\n", netnsid_b, ifidx_b);
> +		goto out_put_netns_b;
> +	}
> +
> +	rcu_assign_pointer(nsim_a->peer, nsim_b);
> +	rcu_assign_pointer(nsim_b->peer, nsim_a);

> @@ -333,6 +333,7 @@ static int nsim_init_netdevsim(struct netdevsim *ns)
>  		goto err_phc_destroy;
>  
>  	rtnl_lock();
> +	RCU_INIT_POINTER(ns->peer, NULL);

since you have to repost - pretty sure ns is zalloc'ed so you don't
have to do this?

>  	err = nsim_bpf_init(ns);
>  	if (err)
>  		goto err_utn_destroy;

Re: [PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

[David Wei]

On 2024-01-31 16:44, Jakub Kicinski wrote:
> On Tue, 30 Jan 2024 13:46:16 -0800 David Wei wrote:
>> [PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports
> 
> There's only 4 patches here, you'll need to repost because you promised
> patchwork 5 by saying 0/5 :(

I'm sorry for being a bad chef and making bad copy pasta :(

Re: [PATCH net-next v8 4/4] netdevsim: add Makefile for selftests

[Jakub Kicinski]

On Tue, 30 Jan 2024 13:46:20 -0800 David Wei wrote:
> Add a Makefile for netdevsim selftests and add selftests path to
> MAINTAINERS
> 
> Signed-off-by: David Wei <dw@davidwei.uk>

Hi David! I'll apply this already. I have to move the current
CI runner for nsim because $$$, and making it more uniform
simplifies things.

Re: [PATCH net-next v8 0/5] netdevsim: link and forward skbs between ports

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 30 Jan 2024 13:46:16 -0800 you wrote:
> This patchset adds the ability to link two netdevsim ports together and
> forward skbs between them, similar to veth. The goal is to use netdevsim
> for testing features e.g. zero copy Rx using io_uring.
> 
> This feature was tested locally on QEMU, and a selftest is included.
> 
> 
> [...]

Here is the summary with links:
  - [net-next,v8,1/4] netdevsim: allow two netdevsim ports to be connected
    (no matching commit)
  - [net-next,v8,2/4] netdevsim: forward skbs from one connected port to another
    (no matching commit)
  - [net-next,v8,3/4] netdevsim: add selftest for forwarding skb between connected ports
    (no matching commit)
  - [net-next,v8,4/4] netdevsim: add Makefile for selftests
    https://git.kernel.org/netdev/net-next/c/8ff25dac88f6

You are awesome, thank you!
-- 
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