netdev: depend on netdev->lock for xdp features

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.

Reviewed-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250408195956.412733-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 7ef9b019193644e96975fe2f1076919abbce6f7d..8c58261de96914dc8363b4edbb9d880669b429c7 100644 (file)
--- 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