Re: [PATCH net-next 1/3] nexthop: Use a dedicated policy for nh_valid_get_del_req()

On 1/19/21 1:55 PM, Jakub Kicinski wrote:

quoted

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index e53e43aef785..d5d88f7c5c11 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c

@@ -36,6 +36,10 @@ static const struct nla_policy rtm_nh_policy[NHA_MAX + 1] = {
 	[NHA_FDB]		= { .type = NLA_FLAG },
 };
 
+static const struct nla_policy rtm_nh_policy_get[NHA_MAX + 1] = {

This is an unnecessary waste of memory if you ask me.

NHA_ID is 1, so we're creating an array of 10 extra NULL elements.

Can you leave the size to the compiler and use ARRAY_SIZE() below?

interesting suggestion in general for netlink attributes.

quoted

+	[NHA_ID]		= { .type = NLA_U32 },
+};
+
 static bool nexthop_notifiers_is_empty(struct net *net)
 {
 	return !net->nexthop.notifier_chain.head;

@@ -1843,27 +1847,14 @@ static int nh_valid_get_del_req(struct nlmsghdr *nlh, u32 *id,
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
 	struct nlattr *tb[NHA_MAX + 1];

This tb array too could be sized to just the highest indexed expected -
NHA_ID in this case.

quoted

-	int err, i;
+	int err;
 
-	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy,
+	err = nlmsg_parse(nlh, sizeof(*nhm), tb, NHA_MAX, rtm_nh_policy_get,
 			  extack);
 	if (err < 0)
 		return err;
 
 	err = -EINVAL;
-	for (i = 0; i < __NHA_MAX; ++i) {
-		if (!tb[i])
-			continue;
-
-		switch (i) {
-		case NHA_ID:
-			break;
-		default:
-			NL_SET_ERR_MSG_ATTR(extack, tb[i],
-					    "Unexpected attribute in request");
-			goto out;
-		}
-	}
 	if (nhm->nh_protocol || nhm->resvd || nhm->nh_scope || nhm->nh_flags) {
 		NL_SET_ERR_MSG(extack, "Invalid values in header");
 		goto out;