[PATCH net-next 6/8] netdev: depend on netdev->lock for xdp features

Jakub Kicinski
2025-04-07T19:01:20Z

Writes to XDP features are now protected by netdev->lock.
Other things we report are based on ops which don't change
once device has been registered. It is safe to stop taking
rtnl_lock, and depend on netdev->lock instead.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/core/netdev-genl.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 7ef9b0191936..8c58261de969 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -38,6 +38,8 @@ netdev_nl_dev_fill(struct net_device *netdev, struct sk_buff *rsp,
u64 xdp_rx_meta = 0;
void *hdr;

+ netdev_assert_locked(netdev); /* note: rtnl_lock may not be held! */
+
hdr = genlmsg_iput(rsp, info);
if (!hdr)
return -EMSGSIZE;
@@ -122,15 +124,14 @@ int netdev_nl_dev_get_doit(struct sk_buff *skb, struct genl_info *info)
if (!rsp)
return -ENOMEM;

- rtnl_lock();
-
- netdev = __dev_get_by_index(genl_info_net(info), ifindex);
- if (netdev)
- err = netdev_nl_dev_fill(netdev, rsp, info);
- else
+ netdev = netdev_get_by_index_lock(genl_info_net(info), ifindex);
+ if (!netdev) {
err = -ENODEV;
+ goto err_free_msg;
+ }

- rtnl_unlock();
+ err = netdev_nl_dev_fill(netdev, rsp, info);
+ netdev_unlock(netdev);

if (err)
goto err_free_msg;
@@ -146,18 +147,15 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
struct netdev_nl_dump_ctx *ctx = netdev_dump_ctx(cb);
struct net *net = sock_net(skb->sk);
- struct net_device *netdev;
- int err = 0;
+ int err;

- rtnl_lock();
- for_each_netdev_dump(net, netdev, ctx->ifindex) {
+ for_each_netdev_lock_scoped(net, netdev, ctx->ifindex) {
err = netdev_nl_dev_fill(netdev, skb, genl_info_dump(cb));
if (err < 0)
- break;
+ return err;
}
- rtnl_unlock();

- return err;
+ return 0;
}

static int
--
2.49.0