[PATCH net-next v6 1/2] net: ethtool: Introduce per-PHY DUMP operations

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

ethnl commands that target a phy_device need a DUMP implementation that
will fill the reply for every PHY behind a netdev. We therefore need to
iterate over the dev->topo to list them.

When multiple PHYs are behind the same netdev, it's also useful to
perform DUMP with a filter on a given netdev, to get the capability of
every PHY.

Implement dedicated genl ->start(), ->dumpit() and ->done() operations
for PHY-targetting command, allowing filtered dumps and using a dump
context that keep track of the PHY iteration for multi-message dump.

PSE-PD and PLCA are converted to this new set of ops along the way.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
V6: Squashed PSE and PLCA into this patch.

 net/ethtool/netlink.c | 180 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 171 insertions(+), 9 deletions(-)

diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 977beeaaa2f9..afb609ed515a 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -357,6 +357,16 @@ struct ethnl_dump_ctx {
 	unsigned long			pos_ifindex;
 };
 
+/**
+ * struct ethnl_perphy_dump_ctx - context for dumpit() PHY-aware callbacks
+ * @ethnl_ctx: generic ethnl context
+ * @pos_phyindex: iterator position for multi-msg DUMP
+ */
+struct ethnl_perphy_dump_ctx {
+	struct ethnl_dump_ctx	ethnl_ctx;
+	unsigned long		pos_phyindex;
+};
+
 static const struct ethnl_request_ops *
 ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
 	[ETHTOOL_MSG_STRSET_GET]	= &ethnl_strset_request_ops,
@@ -407,6 +417,12 @@ static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
 	return (struct ethnl_dump_ctx *)cb->ctx;
 }
 
+static struct ethnl_perphy_dump_ctx *
+ethnl_perphy_dump_context(struct netlink_callback *cb)
+{
+	return (struct ethnl_perphy_dump_ctx *)cb->ctx;
+}
+
 /**
  * ethnl_default_parse() - Parse request message
  * @req_info:    pointer to structure to put data into
@@ -662,6 +678,152 @@ static int ethnl_default_start(struct netlink_callback *cb)
 	return ret;
 }
 
+/* perphy ->start() handler for GET requests */
+static int ethnl_perphy_start(struct netlink_callback *cb)
+{
+	struct ethnl_perphy_dump_ctx *phy_ctx = ethnl_perphy_dump_context(cb);
+	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
+	struct ethnl_dump_ctx *ctx = &phy_ctx->ethnl_ctx;
+	struct ethnl_reply_data *reply_data;
+	const struct ethnl_request_ops *ops;
+	struct ethnl_req_info *req_info;
+	struct genlmsghdr *ghdr;
+	int ret;
+
+	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
+
+	ghdr = nlmsg_data(cb->nlh);
+	ops = ethnl_default_requests[ghdr->cmd];
+	if (WARN_ONCE(!ops, "cmd %u has no ethnl_request_ops\n", ghdr->cmd))
+		return -EOPNOTSUPP;
+	req_info = kzalloc(ops->req_info_size, GFP_KERNEL);
+	if (!req_info)
+		return -ENOMEM;
+	reply_data = kmalloc(ops->reply_data_size, GFP_KERNEL);
+	if (!reply_data) {
+		ret = -ENOMEM;
+		goto free_req_info;
+	}
+
+	/* Don't ignore the dev even for DUMP requests */
+	ret = ethnl_default_parse(req_info, &info->info, ops, false);
+	if (ret < 0)
+		goto free_reply_data;
+
+	ctx->ops = ops;
+	ctx->req_info = req_info;
+	ctx->reply_data = reply_data;
+	ctx->pos_ifindex = 0;
+
+	return 0;
+
+free_reply_data:
+	kfree(reply_data);
+free_req_info:
+	kfree(req_info);
+
+	return ret;
+}
+
+static int ethnl_perphy_dump_one_dev(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct ethnl_perphy_dump_ctx *ctx,
+				     const struct genl_info *info)
+{
+	struct ethnl_dump_ctx *ethnl_ctx = &ctx->ethnl_ctx;
+	struct phy_device_node *pdn;
+	int ret = 0;
+
+	if (!dev->link_topo)
+		return 0;
+
+	xa_for_each_start(&dev->link_topo->phys, ctx->pos_phyindex, pdn,
+			  ctx->pos_phyindex) {
+		ethnl_ctx->req_info->phy_index = ctx->pos_phyindex;
+
+		/* We can re-use the original dump_one as ->prepare_data in
+		 * commands use ethnl_req_get_phydev(), which gets the PHY from
+		 * the req_info->phy_index
+		 */
+		ret = ethnl_default_dump_one(skb, dev, ethnl_ctx, info);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
+static int ethnl_perphy_dump_all_dev(struct sk_buff *skb,
+				     struct ethnl_perphy_dump_ctx *ctx,
+				     const struct genl_info *info)
+{
+	struct ethnl_dump_ctx *ethnl_ctx = &ctx->ethnl_ctx;
+	struct net *net = sock_net(skb->sk);
+	struct net_device *dev;
+	int ret = 0;
+
+	rcu_read_lock();
+	for_each_netdev_dump(net, dev, ethnl_ctx->pos_ifindex) {
+		dev_hold(dev);
+		rcu_read_unlock();
+
+		/* per-PHY commands use ethnl_req_get_phydev(), which needs the
+		 * net_device in the req_info
+		 */
+		ethnl_ctx->req_info->dev = dev;
+		ret = ethnl_perphy_dump_one_dev(skb, dev, ctx, info);
+
+		rcu_read_lock();
+		dev_put(dev);
+
+		if (ret < 0 && ret != -EOPNOTSUPP) {
+			if (likely(skb->len))
+				ret = skb->len;
+			break;
+		}
+		ret = 0;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+/* perphy ->dumpit() handler for GET requests. */
+static int ethnl_perphy_dumpit(struct sk_buff *skb,
+			       struct netlink_callback *cb)
+{
+	struct ethnl_perphy_dump_ctx *ctx = ethnl_perphy_dump_context(cb);
+	struct ethnl_dump_ctx *ethnl_ctx = &ctx->ethnl_ctx;
+	int ret = 0;
+
+	if (ethnl_ctx->req_info->dev) {
+		ret = ethnl_perphy_dump_one_dev(skb, ethnl_ctx->req_info->dev,
+						ctx, genl_info_dump(cb));
+
+		if (ret < 0 && ret != -EOPNOTSUPP && likely(skb->len))
+			ret = skb->len;
+
+		netdev_put(ethnl_ctx->req_info->dev,
+			   &ethnl_ctx->req_info->dev_tracker);
+	} else {
+		ret = ethnl_perphy_dump_all_dev(skb, ctx, genl_info_dump(cb));
+	}
+
+	return ret;
+}
+
+/* perphy ->done() handler for GET requests */
+static int ethnl_perphy_done(struct netlink_callback *cb)
+{
+	struct ethnl_perphy_dump_ctx *ctx = ethnl_perphy_dump_context(cb);
+	struct ethnl_dump_ctx *ethnl_ctx = &ctx->ethnl_ctx;
+
+	kfree(ethnl_ctx->reply_data);
+	kfree(ethnl_ctx->req_info);
+
+	return 0;
+}
+
 /* default ->done() handler for GET requests */
 static int ethnl_default_done(struct netlink_callback *cb)
 {
@@ -1200,9 +1362,9 @@ static const struct genl_ops ethtool_genl_ops[] = {
 	{
 		.cmd	= ETHTOOL_MSG_PSE_GET,
 		.doit	= ethnl_default_doit,
-		.start	= ethnl_default_start,
-		.dumpit	= ethnl_default_dumpit,
-		.done	= ethnl_default_done,
+		.start	= ethnl_perphy_start,
+		.dumpit	= ethnl_perphy_dumpit,
+		.done	= ethnl_perphy_done,
 		.policy = ethnl_pse_get_policy,
 		.maxattr = ARRAY_SIZE(ethnl_pse_get_policy) - 1,
 	},
@@ -1224,9 +1386,9 @@ static const struct genl_ops ethtool_genl_ops[] = {
 	{
 		.cmd	= ETHTOOL_MSG_PLCA_GET_CFG,
 		.doit	= ethnl_default_doit,
-		.start	= ethnl_default_start,
-		.dumpit	= ethnl_default_dumpit,
-		.done	= ethnl_default_done,
+		.start	= ethnl_perphy_start,
+		.dumpit	= ethnl_perphy_dumpit,
+		.done	= ethnl_perphy_done,
 		.policy = ethnl_plca_get_cfg_policy,
 		.maxattr = ARRAY_SIZE(ethnl_plca_get_cfg_policy) - 1,
 	},
@@ -1240,9 +1402,9 @@ static const struct genl_ops ethtool_genl_ops[] = {
 	{
 		.cmd	= ETHTOOL_MSG_PLCA_GET_STATUS,
 		.doit	= ethnl_default_doit,
-		.start	= ethnl_default_start,
-		.dumpit	= ethnl_default_dumpit,
-		.done	= ethnl_default_done,
+		.start	= ethnl_perphy_start,
+		.dumpit	= ethnl_perphy_dumpit,
+		.done	= ethnl_perphy_done,
 		.policy = ethnl_plca_get_status_policy,
 		.maxattr = ARRAY_SIZE(ethnl_plca_get_status_policy) - 1,
 	},
-- 
2.49.0