Merge branch 'net-use-netdev-lock-to-protect-napi'

Jakub Kicinski says:

====================
net: use netdev->lock to protect NAPI

We recently added a lock member to struct net_device, with a vague
plan to start using it to protect netdev-local state, removing
the need to take rtnl_lock for new configuration APIs.

Lay some groundwork and use this lock for protecting NAPI APIs.

v1: https://lore.kernel.org/20250114035118.110297-1-kuba@kernel.org
====================

Link: https://patch.msgid.link/20250115035319.559603-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 25 insertions, 31 deletions

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index c59619a2ec23..715f85c6b62e 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -167,7 +167,7 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi,
 	void *hdr;
 	pid_t pid;
 
-	if (!(napi->dev->flags & IFF_UP))
+	if (!napi->dev->up)
 		return 0;
 
 	hdr = genlmsg_iput(rsp, info);
@@ -229,20 +229,15 @@ int netdev_nl_napi_get_doit(struct sk_buff *skb, struct genl_info *info)
 	if (!rsp)
 		return -ENOMEM;
 
-	rtnl_lock();
-	rcu_read_lock();
-
-	napi = netdev_napi_by_id(genl_info_net(info), napi_id);
+	napi = netdev_napi_by_id_lock(genl_info_net(info), napi_id);
 	if (napi) {
 		err = netdev_nl_napi_fill_one(rsp, napi, info);
+		netdev_unlock(napi->dev);
 	} else {
 		NL_SET_BAD_ATTR(info->extack, info->attrs[NETDEV_A_NAPI_ID]);
 		err = -ENOENT;
 	}
 
-	rcu_read_unlock();
-	rtnl_unlock();
-
 	if (err) {
 		goto err_free_msg;
 	} else if (!rsp->len) {
@@ -266,7 +261,7 @@ netdev_nl_napi_dump_one(struct net_device *netdev, struct sk_buff *rsp,
 	unsigned int prev_id;
 	int err = 0;
 
-	if (!(netdev->flags & IFF_UP))
+	if (!netdev->up)
 		return err;
 
 	prev_id = UINT_MAX;
@@ -301,22 +296,22 @@ int netdev_nl_napi_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	if (info->attrs[NETDEV_A_NAPI_IFINDEX])
 		ifindex = nla_get_u32(info->attrs[NETDEV_A_NAPI_IFINDEX]);
 
-	rtnl_lock();
 	if (ifindex) {
-		netdev = __dev_get_by_index(net, ifindex);
-		if (netdev)
+		netdev = netdev_get_by_index_lock(net, ifindex);
+		if (netdev) {
 			err = netdev_nl_napi_dump_one(netdev, skb, info, ctx);
-		else
+			netdev_unlock(netdev);
+		} else {
 			err = -ENODEV;
+		}
 	} else {
-		for_each_netdev_dump(net, netdev, ctx->ifindex) {
+		for_each_netdev_lock_scoped(net, netdev, ctx->ifindex) {
 			err = netdev_nl_napi_dump_one(netdev, skb, info, ctx);
 			if (err < 0)
 				break;
 			ctx->napi_id = 0;
 		}
 	}
-	rtnl_unlock();
 
 	return err;
 }
@@ -357,20 +352,15 @@ int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info)
 
 	napi_id = nla_get_u32(info->attrs[NETDEV_A_NAPI_ID]);
 
-	rtnl_lock();
-	rcu_read_lock();
-
-	napi = netdev_napi_by_id(genl_info_net(info), napi_id);
+	napi = netdev_napi_by_id_lock(genl_info_net(info), napi_id);
 	if (napi) {
 		err = netdev_nl_napi_set_config(napi, info);
+		netdev_unlock(napi->dev);
 	} else {
 		NL_SET_BAD_ATTR(info->extack, info->attrs[NETDEV_A_NAPI_ID]);
 		err = -ENOENT;
 	}
 
-	rcu_read_unlock();
-	rtnl_unlock();
-
 	return err;
 }
 
@@ -442,7 +432,7 @@ netdev_nl_queue_fill(struct sk_buff *rsp, struct net_device *netdev, u32 q_idx,
 {
 	int err;
 
-	if (!(netdev->flags & IFF_UP))
+	if (!netdev->up)
 		return -ENOENT;
 
 	err = netdev_nl_queue_validate(netdev, q_idx, q_type);
@@ -474,11 +464,13 @@ int netdev_nl_queue_get_doit(struct sk_buff *skb, struct genl_info *info)
 
 	rtnl_lock();
 
-	netdev = __dev_get_by_index(genl_info_net(info), ifindex);
-	if (netdev)
+	netdev = netdev_get_by_index_lock(genl_info_net(info), ifindex);
+	if (netdev) {
 		err = netdev_nl_queue_fill(rsp, netdev, q_id, q_type, info);
-	else
+		netdev_unlock(netdev);
+	} else {
 		err = -ENODEV;
+	}
 
 	rtnl_unlock();
 
@@ -499,7 +491,7 @@ netdev_nl_queue_dump_one(struct net_device *netdev, struct sk_buff *rsp,
 {
 	int err = 0;
 
-	if (!(netdev->flags & IFF_UP))
+	if (!netdev->up)
 		return err;
 
 	for (; ctx->rxq_idx < netdev->real_num_rx_queues; ctx->rxq_idx++) {
@@ -532,13 +524,15 @@ int netdev_nl_queue_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 
 	rtnl_lock();
 	if (ifindex) {
-		netdev = __dev_get_by_index(net, ifindex);
-		if (netdev)
+		netdev = netdev_get_by_index_lock(net, ifindex);
+		if (netdev) {
 			err = netdev_nl_queue_dump_one(netdev, skb, info, ctx);
-		else
+			netdev_unlock(netdev);
+		} else {
 			err = -ENODEV;
+		}
 	} else {
-		for_each_netdev_dump(net, netdev, ctx->ifindex) {
+		for_each_netdev_lock_scoped(net, netdev, ctx->ifindex) {
 			err = netdev_nl_queue_dump_one(netdev, skb, info, ctx);
 			if (err < 0)
 				break;