Date: Fri, 28 Jul 2023 17:47:17 -0700
From: Amritha Nambiar <amritha.nambiar@...el.com>
To: netdev@...r.kernel.org, kuba@...nel.org, davem@...emloft.net
Cc: sridhar.samudrala@...el.com, amritha.nambiar@...el.com
Subject: [net-next PATCH v1 5/9] netdev-genl: Add netlink framework
 functions for napi

Implement the netdev netlink framework functions for
napi support. The netdev structure tracks all the napi
instances and napi fields. The napi instances and associated
queue[s] can be retrieved this way.

Signed-off-by: Amritha Nambiar <amritha.nambiar@...el.com>
---
 net/core/netdev-genl.c |  253 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 251 insertions(+), 2 deletions(-)

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index e35cfa3cd173..ca3ed6eb457b 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -8,6 +8,20 @@
 
 #include "netdev-genl-gen.h"
 
+struct netdev_nl_dump_ctx {
+	int dev_entry_hash;
+	int dev_entry_idx;
+	int napi_idx;
+};
+
+static inline struct netdev_nl_dump_ctx *
+netdev_dump_ctx(struct netlink_callback *cb)
+{
+	NL_ASSERT_DUMP_CTX_FITS(struct netdev_nl_dump_ctx);
+
+	return (struct netdev_nl_dump_ctx *)cb->ctx;
+}
+
 static int
 netdev_nl_dev_fill(struct net_device *netdev, struct sk_buff *rsp,
 		   u32 portid, u32 seq, int flags, u32 cmd)
@@ -120,14 +134,249 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
+static int
+netdev_nl_napi_fill_one(struct sk_buff *msg, struct napi_struct *napi)
+{
+	struct netdev_rx_queue *rx_queue, *rxq;
+	struct netdev_queue *tx_queue, *txq;
+	unsigned int rx_qid, tx_qid;
+	struct nlattr *napi_info;
+
+	napi_info = nla_nest_start(msg, NETDEV_A_NAPI_NAPI_INFO);
+	if (!napi_info)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(msg, NETDEV_A_NAPI_INFO_ENTRY_NAPI_ID, napi->napi_id))
+		goto nla_put_failure;
+
+	list_for_each_entry_safe(rx_queue, rxq, &napi->napi_rxq_list, q_list) {
+		rx_qid = get_netdev_rx_queue_index(rx_queue);
+		if (nla_put_u32(msg, NETDEV_A_NAPI_INFO_ENTRY_RX_QUEUES, rx_qid))
+			goto nla_put_failure;
+	}
+
+	list_for_each_entry_safe(tx_queue, txq, &napi->napi_txq_list, q_list) {
+		tx_qid = get_netdev_queue_index(tx_queue);
+		if (nla_put_u32(msg, NETDEV_A_NAPI_INFO_ENTRY_TX_QUEUES, tx_qid))
+			goto nla_put_failure;
+	}
+
+	nla_nest_end(msg, napi_info);
+	return 0;
+nla_put_failure:
+	nla_nest_cancel(msg, napi_info);
+	return -EMSGSIZE;
+}
+
+static int
+netdev_nl_napi_fill(struct net_device *netdev, struct sk_buff *msg, int *start)
+{
+	struct napi_struct *napi, *n;
+	int i = 0;
+
+	list_for_each_entry_safe(napi, n, &netdev->napi_list, dev_list) {
+		if (i < *start) {
+			i++;
+			continue;
+		}
+		if (netdev_nl_napi_fill_one(msg, napi))
+			return -EMSGSIZE;
+		*start = ++i;
+	}
+	return 0;
+}
+
+static int
+netdev_nl_napi_prepare_fill(struct net_device *netdev, u32 portid, u32 seq,
+			    int flags, u32 cmd)
+{
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+	bool last = false;
+	int index = 0;
+	void *hdr;
+	int err;
+
+	while (!last) {
+		int tmp_index = index;
+
+		skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+		if (!skb)
+			return -ENOMEM;
+
+		hdr = genlmsg_put(skb, portid, seq, &netdev_nl_family,
+				  flags | NLM_F_MULTI, cmd);
+		if (!hdr) {
+			err = -EMSGSIZE;
+			goto nla_put_failure;
+		}
+		err = netdev_nl_napi_fill(netdev, skb, &index);
+		if (!err)
+			last = true;
+		else if (err != -EMSGSIZE || tmp_index == index)
+			goto nla_put_failure;
+
+		genlmsg_end(skb, hdr);
+		err = genlmsg_unicast(dev_net(netdev), skb, portid);
+		if (err)
+			return err;
+	}
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+	nlh = nlmsg_put(skb, portid, seq, NLMSG_DONE, 0, flags | NLM_F_MULTI);
+	if (!nlh) {
+		err = -EMSGSIZE;
+		goto nla_put_failure;
+	}
+
+	return genlmsg_unicast(dev_net(netdev), skb, portid);
+
+nla_put_failure:
+	nlmsg_free(skb);
+	return err;
+}
+
+static int
+netdev_nl_napi_info_fill(struct net_device *netdev, u32 portid, u32 seq,
+			 int flags, u32 cmd)
+{
+	struct sk_buff *skb;
+	void *hdr;
+	int err;
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(skb, portid, seq, &netdev_nl_family, flags, cmd);
+	if (!hdr) {
+		err = -EMSGSIZE;
+		goto err_free_msg;
+	}
+	if (nla_put_u32(skb, NETDEV_A_NAPI_IFINDEX, netdev->ifindex)) {
+		genlmsg_cancel(skb, hdr);
+		err = -EINVAL;
+		goto err_free_msg;
+	}
+
+	genlmsg_end(skb, hdr);
+
+	err = genlmsg_unicast(dev_net(netdev), skb, portid);
+	if (err)
+		return err;
+
+	return netdev_nl_napi_prepare_fill(netdev, portid, seq, flags, cmd);
+
+err_free_msg:
+	nlmsg_free(skb);
+	return err;
+}
+
 int netdev_nl_napi_get_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	return -EOPNOTSUPP;
+	struct net_device *netdev;
+	u32 ifindex;
+	int err;
+
+	if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_NAPI_IFINDEX))
+		return -EINVAL;
+
+	ifindex = nla_get_u32(info->attrs[NETDEV_A_NAPI_IFINDEX]);
+
+	rtnl_lock();
+
+	netdev = __dev_get_by_index(genl_info_net(info), ifindex);
+	if (netdev)
+		err = netdev_nl_napi_info_fill(netdev, info->snd_portid,
+					       info->snd_seq, 0, info->genlhdr->cmd);
+	else
+		err = -ENODEV;
+
+	rtnl_unlock();
+
+	return err;
+}
+
+static int
+netdev_nl_napi_dump_entry(struct net_device *netdev, struct sk_buff *rsp,
+			  struct netlink_callback *cb, int *start)
+{
+	int index = *start;
+	int tmp_index = index;
+	void *hdr;
+	int err;
+
+	hdr = genlmsg_put(rsp, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
+			  &netdev_nl_family, NLM_F_MULTI, NETDEV_CMD_NAPI_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(rsp, NETDEV_A_NAPI_IFINDEX, netdev->ifindex))
+		goto nla_put_failure;
+
+	err =  netdev_nl_napi_fill(netdev, rsp, &index);
+	if (err && (err != -EMSGSIZE || tmp_index == index))
+		goto nla_put_failure;
+
+	*start = index;
+	genlmsg_end(rsp, hdr);
+
+	return err;
+
+nla_put_failure:
+	genlmsg_cancel(rsp, hdr);
+	return -EINVAL;
 }
 
 int netdev_nl_napi_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	return -EOPNOTSUPP;
+	struct netdev_nl_dump_ctx *ctx = netdev_dump_ctx(cb);
+	struct net *net = sock_net(skb->sk);
+	struct net_device *netdev;
+	int idx = 0, s_idx, n_idx;
+	int h, s_h;
+	int err;
+
+	s_h = ctx->dev_entry_hash;
+	s_idx = ctx->dev_entry_idx;
+	n_idx = ctx->napi_idx;
+
+	rtnl_lock();
+
+	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
+		struct hlist_head *head;
+
+		idx = 0;
+		head = &net->dev_index_head[h];
+		hlist_for_each_entry(netdev, head, index_hlist) {
+			if (idx < s_idx)
+				goto cont;
+			err = netdev_nl_napi_dump_entry(netdev, skb, cb, &n_idx);
+			if (err == -EMSGSIZE)
+				goto out;
+			n_idx = 0;
+			if (err < 0)
+				break;
+cont:
+			idx++;
+		}
+	}
+
+	rtnl_unlock();
+
+	return err;
+
+out:
+	rtnl_unlock();
+
+	ctx->dev_entry_idx = idx;
+	ctx->dev_entry_hash = h;
+	ctx->napi_idx = n_idx;
+	cb->seq = net->dev_base_seq;
+
+	return skb->len;
 }
 
 static int netdev_genl_netdevice_event(struct notifier_block *nb,

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