There is no need to call this helper: it will check if the address ID
attribute is set, but this attribute has already been parsed previously.

Indeed, the value has been set in 'entry->addr.id' if it was set and
positive, which is what we were looking at. Then only looking at this
already parsed value is enough, not need to re-extract all Netlink
attributes again.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm_kernel.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
index 82e59f9c6dd9..0ebf43be9939 100644
--- a/net/mptcp/pm_kernel.c
+++ b/net/mptcp/pm_kernel.c
@@ -720,7 +720,7 @@ static void __mptcp_pm_release_addr_entry(struct mptcp_pm_addr_entry *entry)
 
 static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
 					     struct mptcp_pm_addr_entry *entry,
-					     bool needs_id, bool replace)
+					     bool replace)
 {
 	struct mptcp_pm_addr_entry *cur, *del_entry = NULL;
 	int ret = -EINVAL;
@@ -779,7 +779,7 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
 		}
 	}
 
-	if (!entry->addr.id && needs_id) {
+	if (!entry->addr.id) {
 find_next:
 		entry->addr.id = find_next_zero_bit(pernet->id_bitmap,
 						    MPTCP_PM_MAX_ADDR_ID + 1,
@@ -790,7 +790,7 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
 		}
 	}
 
-	if (!entry->addr.id && needs_id)
+	if (!entry->addr.id)
 		goto out;
 
 	__set_bit(entry->addr.id, pernet->id_bitmap);
@@ -923,7 +923,7 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk,
 		return -ENOMEM;
 
 	entry->addr.port = 0;
-	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true, false);
+	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, false);
 	if (ret < 0)
 		kfree(entry);
 
@@ -977,18 +977,6 @@ static int mptcp_nl_add_subflow_or_signal_addr(struct net *net,
 	return 0;
 }
 
-static bool mptcp_pm_has_addr_attr_id(const struct nlattr *attr,
-				      struct genl_info *info)
-{
-	struct nlattr *tb[MPTCP_PM_ADDR_ATTR_MAX + 1];
-
-	if (!nla_parse_nested_deprecated(tb, MPTCP_PM_ADDR_ATTR_MAX, attr,
-					 mptcp_pm_address_nl_policy, info->extack) &&
-	    tb[MPTCP_PM_ADDR_ATTR_ID])
-		return true;
-	return false;
-}
-
 /* Add an MPTCP endpoint */
 int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)
 {
@@ -1037,9 +1025,7 @@ int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)
 			goto out_free;
 		}
 	}
-	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry,
-						!mptcp_pm_has_addr_attr_id(attr, info),
-						true);
+	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true);
 	if (ret < 0) {
 		GENL_SET_ERR_MSG_FMT(info, "too many addresses or duplicate one: %d", ret);
 		goto out_free;

-- 
2.53.0

Hello,

On 03/04/2026 13:29, Matthieu Baerts (NGI0) wrote:
> There is no need to call this helper: it will check if the address ID
> attribute is set, but this attribute has already been parsed previously.
> 
> Indeed, the value has been set in 'entry->addr.id' if it was set and
> positive, which is what we were looking at. Then only looking at this
> already parsed value is enough, not need to re-extract all Netlink
> attributes again.

Sashiko [1] is complaining that endpoints with an ID 0 are now no longer
supported. But they were never supposed to: "ip mptcp endpoint add id 0"
reports an error.

In fact, this patch is for 'net': from what I see, this patch reverts
commit 584f38942626 ("mptcp: add needs_id for netlink appending addr"),
which should not have been introduced. Other tools could happily add
endpoints with an unexpected ID 0.

If that's OK with the net maintainers, I suggest dropping only this
patch: the rest of the series is OK and not related to it. I will send
this exact same patch for 'net' after having adapted the commit message
and added a "Fixes" tag.

[1]
https://sashiko.dev/#/patchset/20260403-net-next-mptcp-msg_eor-misc-v1-0-b0b33bea3fed%40kernel.org

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.