Re: [PATCH net-next v3 4/5] net/sched: act_api: conditional notification of events

[Jiri Pirko <jiri@resnulli.us>]

Wed, Dec 06, 2023 at 05:44:15PM CET, pctammela@mojatatu.com wrote:
>As of today tc-action events are unconditionally built and sent to
>RTNLGRP_TC. As with the introduction of rtnl_notify_needed we can check
>before-hand if they are really needed.
>
>Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
>---
> net/sched/act_api.c | 105 ++++++++++++++++++++++++++++++++------------
> 1 file changed, 76 insertions(+), 29 deletions(-)
>
>diff --git a/net/sched/act_api.c b/net/sched/act_api.c
>index abec5c45b5a4..c15c2083ac84 100644
>--- a/net/sched/act_api.c
>+++ b/net/sched/act_api.c
>@@ -1785,31 +1785,45 @@ static int tcf_action_delete(struct net *net, struct tc_action *actions[])
> 	return 0;
> }
> 
>-static int
>-tcf_reoffload_del_notify(struct net *net, struct tc_action *action)
>+static struct sk_buff *tcf_reoffload_del_notify_msg(struct net *net,
>+						    struct tc_action *action)
> {
> 	size_t attr_size = tcf_action_fill_size(action);
> 	struct tc_action *actions[TCA_ACT_MAX_PRIO] = {
> 		[0] = action,
> 	};
>-	const struct tc_action_ops *ops = action->ops;
> 	struct sk_buff *skb;
>-	int ret;
> 
>-	skb = alloc_skb(attr_size <= NLMSG_GOODSIZE ? NLMSG_GOODSIZE : attr_size,
>-			GFP_KERNEL);
>+	skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);

I don't follow. I think you promissed to have this unrelated change as a
separate patch, right? Could you? Unrelated to this patch.


> 	if (!skb)
>-		return -ENOBUFS;
>+		return ERR_PTR(-ENOBUFS);
> 
> 	if (tca_get_fill(skb, actions, 0, 0, 0, RTM_DELACTION, 0, 1, NULL) <= 0) {
> 		kfree_skb(skb);
>-		return -EINVAL;
>+		return ERR_PTR(-EINVAL);
> 	}
> 
>+	return skb;
>+}
>+
>+static int tcf_reoffload_del_notify(struct net *net, struct tc_action *action)
>+{
>+	const struct tc_action_ops *ops = action->ops;
>+	struct sk_buff *skb = NULL;
>+	int ret;
>+
>+	if (!rtnl_notify_needed(net, 0, RTNLGRP_TC))
>+		goto skip_msg;
>+
>+	skb = tcf_reoffload_del_notify_msg(net, action);
>+	if (IS_ERR(skb))
>+		return PTR_ERR(skb);
>+
>+skip_msg:
> 	ret = tcf_idr_release_unsafe(action);
> 	if (ret == ACT_P_DELETED) {
> 		module_put(ops->owner);
>-		ret = rtnetlink_send(skb, net, 0, RTNLGRP_TC, 0);
>+		ret = rtnetlink_maybe_send(skb, net, 0, RTNLGRP_TC, 0);
> 	} else {
> 		kfree_skb(skb);
> 	}
>@@ -1875,25 +1889,42 @@ int tcf_action_reoffload_cb(flow_indr_block_bind_cb_t *cb,
> 	return 0;
> }
> 
>-static int
>-tcf_del_notify(struct net *net, struct nlmsghdr *n, struct tc_action *actions[],
>-	       u32 portid, size_t attr_size, struct netlink_ext_ack *extack)
>+static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,
>+					  struct tc_action *actions[],
>+					  u32 portid, size_t attr_size,
>+					  struct netlink_ext_ack *extack)
> {
>-	int ret;
> 	struct sk_buff *skb;
> 
>-	skb = alloc_skb(attr_size <= NLMSG_GOODSIZE ? NLMSG_GOODSIZE : attr_size,
>-			GFP_KERNEL);
>+	skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
> 	if (!skb)
>-		return -ENOBUFS;
>+		return ERR_PTR(-ENOBUFS);
> 
> 	if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, RTM_DELACTION,
> 			 0, 2, extack) <= 0) {
> 		NL_SET_ERR_MSG(extack, "Failed to fill netlink TC action attributes");
> 		kfree_skb(skb);
>-		return -EINVAL;
>+		return ERR_PTR(-EINVAL);
> 	}
> 
>+	return skb;
>+}
>+
>+static int tcf_del_notify(struct net *net, struct nlmsghdr *n,
>+			  struct tc_action *actions[], u32 portid,
>+			  size_t attr_size, struct netlink_ext_ack *extack)
>+{
>+	struct sk_buff *skb = NULL;
>+	int ret;
>+
>+	if (!rtnl_notify_needed(net, n->nlmsg_flags, RTNLGRP_TC))
>+		goto skip_msg;
>+
>+	skb = tcf_del_notify_msg(net, n, actions, portid, attr_size, extack);
>+	if (IS_ERR(skb))
>+		return PTR_ERR(skb);
>+
>+skip_msg:
> 	/* now do the delete */
> 	ret = tcf_action_delete(net, actions);
> 	if (ret < 0) {
>@@ -1902,9 +1933,8 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct tc_action *actions[],
> 		return ret;
> 	}
> 
>-	ret = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
>-			     n->nlmsg_flags & NLM_F_ECHO);
>-	return ret;
>+	return rtnetlink_maybe_send(skb, net, portid, RTNLGRP_TC,
>+				    n->nlmsg_flags & NLM_F_ECHO);
> }
> 
> static int
>@@ -1955,26 +1985,43 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
> 	return ret;
> }
> 
>-static int
>-tcf_add_notify(struct net *net, struct nlmsghdr *n, struct tc_action *actions[],
>-	       u32 portid, size_t attr_size, struct netlink_ext_ack *extack)
>+static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,
>+					  struct tc_action *actions[],
>+					  u32 portid, size_t attr_size,
>+					  struct netlink_ext_ack *extack)
> {
> 	struct sk_buff *skb;
> 
>-	skb = alloc_skb(attr_size <= NLMSG_GOODSIZE ? NLMSG_GOODSIZE : attr_size,
>-			GFP_KERNEL);
>+	skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
> 	if (!skb)
>-		return -ENOBUFS;
>+		return ERR_PTR(-ENOBUFS);
> 
> 	if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, n->nlmsg_flags,
> 			 RTM_NEWACTION, 0, 0, extack) <= 0) {
> 		NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action");
> 		kfree_skb(skb);
>-		return -EINVAL;
>+		return ERR_PTR(-EINVAL);
> 	}
> 
>-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
>-			      n->nlmsg_flags & NLM_F_ECHO);
>+	return skb;
>+}
>+
>+static int tcf_add_notify(struct net *net, struct nlmsghdr *n,
>+			  struct tc_action *actions[], u32 portid,
>+			  size_t attr_size, struct netlink_ext_ack *extack)
>+{
>+	struct sk_buff *skb = NULL;
>+
>+	if (!rtnl_notify_needed(net, n->nlmsg_flags, RTNLGRP_TC))
>+		goto skip_msg;
>+
>+	skb = tcf_add_notify_msg(net, n, actions, portid, attr_size, extack);
>+	if (IS_ERR(skb))
>+		return PTR_ERR(skb);
>+
>+skip_msg:
>+	return rtnetlink_maybe_send(skb, net, portid, RTNLGRP_TC,
>+				    n->nlmsg_flags & NLM_F_ECHO);
> }
> 
> static int tcf_action_add(struct net *net, struct nlattr *nla,
>-- 
>2.40.1
>