[PATCH 6.12.y 1/3] mptcp: pm: use for_each_subflow helper

[Sasha Levin <sashal@kernel.org>]

From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>

[ Upstream commit f81689172429885d6c2c7c3dd4926ec626e794bb ]

Similar to most places in the MPTCP code. So instead of passing the
subflow list and use list_for_each_entry(subflow, list, node), pass the
msk and use mptcp_for_each_subflow(msk, subflow).

That's clearer and more uniform with the rest.

While at it, add 'pm_' prefix for the exported one to easily identify
the origin. Plus replace 'lookup' by 'has', because a bool is returned.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260605-net-next-mptcp-add-addr6-port-ts-v2-9-758e7ca73f4d@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Stable backport adaptation for 2ac7d6e620764f1fc79eb4edd3610a7a661981ca:

The stable tree keeps both subflow lookups and their callers in
pm_netlink.c. Apply the iterator conversion there, retaining private
helpers and using has_subflow_saddr() for the source-address lookup.
Drop the upstream pm.c, pm_userspace.c and protocol.h hunks, which assume
helper moves and a userspace callback not present on this branch.

Rename pm_netlink.c to pm_kernel.c and update the Makefile so the target
patch finds its existing ID0 removal function at the upstream path.
Rename the existing remove_anno_list_by_saddr() and
mptcp_pm_nl_rm_subflow_received() helpers to mptcp_pm_announced_remove()
and mptcp_pm_rm_subflow(), updating all callers, to provide the target's
helper name and patch context. Keep their stable implementations and
static linkage. No functions are added and the ID0 fix itself remains
for the target commit.

[ sashal: Reduced backport -- upstream f816891724298 touches 4 file(s), this
  backport carries 2. Not backported here:
  net/mptcp/pm.c
  net/mptcp/pm_userspace.c
  net/mptcp/protocol.h
  This note is generated from the file lists only; see the resolution record
  for the reasoning. ]

Stable-dep-of: 2ac7d6e62076 ("mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mptcp/Makefile                      |  2 +-
 net/mptcp/{pm_netlink.c => pm_kernel.c} | 41 ++++++++++++-------------
 2 files changed, 21 insertions(+), 22 deletions(-)
 rename net/mptcp/{pm_netlink.c => pm_kernel.c} (98%)

diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index bcf1dbf3a432f..8d5efaed6f98c 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -2,7 +2,7 @@
 obj-$(CONFIG_MPTCP) += mptcp.o
 
 mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o \
-	   mib.o pm_netlink.o sockopt.o pm_userspace.o fastopen.o sched.o \
+	   mib.o pm_kernel.o sockopt.o pm_userspace.o fastopen.o sched.o \
 	   mptcp_pm_gen.o
 
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_kernel.c
similarity index 98%
rename from net/mptcp/pm_netlink.c
rename to net/mptcp/pm_kernel.c
index 7ea8ccd16df2f..44f7f419e69a2 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_kernel.c
@@ -109,14 +109,14 @@ static void remote_address(const struct sock_common *skc,
 #endif
 }
 
-static bool lookup_subflow_by_saddr(const struct list_head *list,
-				    const struct mptcp_addr_info *saddr)
+static bool has_subflow_saddr(const struct mptcp_sock *msk,
+			      const struct mptcp_addr_info *saddr)
 {
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_addr_info cur;
 	struct sock_common *skc;
 
-	list_for_each_entry(subflow, list, node) {
+	mptcp_for_each_subflow(msk, subflow) {
 		skc = (struct sock_common *)mptcp_subflow_tcp_sock(subflow);
 
 		mptcp_local_address(skc, &cur);
@@ -127,13 +127,13 @@ static bool lookup_subflow_by_saddr(const struct list_head *list,
 	return false;
 }
 
-static bool lookup_subflow_by_daddr(const struct list_head *list,
-				    const struct mptcp_addr_info *daddr)
+static bool has_subflow_daddr(const struct mptcp_sock *msk,
+			      const struct mptcp_addr_info *daddr)
 {
 	struct mptcp_subflow_context *subflow;
 	struct mptcp_addr_info cur;
 
-	list_for_each_entry(subflow, list, node) {
+	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
 		if (!((1 << inet_sk_state_load(ssk)) &
@@ -843,7 +843,7 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
 	mptcp_pm_announce_addr(msk, &remote, true);
 	mptcp_pm_nl_addr_send_ack(msk);
 
-	if (lookup_subflow_by_daddr(&msk->conn_list, &remote))
+	if (has_subflow_daddr(msk, &remote))
 		return;
 
 	/* pick id 0 port, if none is provided the remote address */
@@ -1047,8 +1047,8 @@ static void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
 	mptcp_pm_nl_rm_addr_or_subflow(msk, &msk->pm.rm_list_rx, MPTCP_MIB_RMADDR);
 }
 
-static void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk,
-					    const struct mptcp_rm_list *rm_list)
+static void mptcp_pm_rm_subflow(struct mptcp_sock *msk,
+				const struct mptcp_rm_list *rm_list)
 {
 	mptcp_pm_nl_rm_addr_or_subflow(msk, rm_list, MPTCP_MIB_RMSUBFLOW);
 }
@@ -1572,7 +1572,7 @@ int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)
 	return ret;
 }
 
-static bool remove_anno_list_by_saddr(struct mptcp_sock *msk,
+static bool mptcp_pm_announced_remove(struct mptcp_sock *msk,
 				      const struct mptcp_addr_info *addr)
 {
 	struct mptcp_pm_add_entry *entry;
@@ -1601,7 +1601,7 @@ static bool mptcp_pm_remove_anno_addr(struct mptcp_sock *msk,
 
 	list.ids[list.nr++] = mptcp_endp_get_local_id(msk, addr);
 
-	ret = remove_anno_list_by_saddr(msk, addr);
+	ret = mptcp_pm_announced_remove(msk, addr);
 	if (ret || force) {
 		spin_lock_bh(&msk->pm.lock);
 		if (ret)
@@ -1638,7 +1638,7 @@ static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net,
 			goto next;
 
 		lock_sock(sk);
-		remove_subflow = lookup_subflow_by_saddr(&msk->conn_list, addr);
+		remove_subflow = has_subflow_saddr(msk, addr);
 		mptcp_pm_remove_anno_addr(msk, addr, remove_subflow &&
 					  !(entry->flags & MPTCP_PM_ADDR_FLAG_IMPLICIT));
 
@@ -1646,7 +1646,7 @@ static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net,
 
 		spin_lock_bh(&msk->pm.lock);
 		if (remove_subflow)
-			mptcp_pm_nl_rm_subflow_received(msk, &list);
+			mptcp_pm_rm_subflow(msk, &list);
 		if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW)
 			__mark_subflow_endp_available(msk, list.ids[0]);
 		else /* mark endp ID as available, e.g. Signal or MPC endp */
@@ -1688,7 +1688,7 @@ static int mptcp_nl_remove_id_zero_address(struct net *net,
 		lock_sock(sk);
 		spin_lock_bh(&msk->pm.lock);
 		mptcp_pm_remove_addr(msk, &list);
-		mptcp_pm_nl_rm_subflow_received(msk, &list);
+		mptcp_pm_rm_subflow(msk, &list);
 		__mark_subflow_endp_available(msk, 0);
 		spin_unlock_bh(&msk->pm.lock);
 		release_sock(sk);
@@ -1761,10 +1761,9 @@ void mptcp_pm_remove_addrs(struct mptcp_sock *msk, struct list_head *rm_list)
 			break;
 
 		/* only delete if either announced or matching a subflow */
-		if (remove_anno_list_by_saddr(msk, &entry->addr))
+		if (mptcp_pm_announced_remove(msk, &entry->addr))
 			anno_nr++;
-		else if (!lookup_subflow_by_saddr(&msk->conn_list,
-						  &entry->addr))
+		else if (!has_subflow_saddr(msk, &entry->addr))
 			continue;
 
 		alist.ids[alist.nr++] = entry->addr.id;
@@ -1787,11 +1786,11 @@ static void mptcp_pm_flush_addrs_and_subflows(struct mptcp_sock *msk,
 
 	list_for_each_entry(entry, rm_list, list) {
 		if (slist.nr < MPTCP_RM_IDS_MAX &&
-		    lookup_subflow_by_saddr(&msk->conn_list, &entry->addr))
+		    has_subflow_saddr(msk, &entry->addr))
 			slist.ids[slist.nr++] = mptcp_endp_get_local_id(msk, &entry->addr);
 
 		if (alist.nr < MPTCP_RM_IDS_MAX &&
-		    remove_anno_list_by_saddr(msk, &entry->addr))
+		    mptcp_pm_announced_remove(msk, &entry->addr))
 			alist.ids[alist.nr++] = mptcp_endp_get_local_id(msk, &entry->addr);
 	}
 
@@ -1801,7 +1800,7 @@ static void mptcp_pm_flush_addrs_and_subflows(struct mptcp_sock *msk,
 		mptcp_pm_remove_addr(msk, &alist);
 	}
 	if (slist.nr)
-		mptcp_pm_nl_rm_subflow_received(msk, &slist);
+		mptcp_pm_rm_subflow(msk, &slist);
 	/* Reset counters: maybe some subflows have been removed before */
 	bitmap_fill(msk->pm.id_avail_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
 	msk->pm.local_addr_used = 0;
@@ -2101,7 +2100,7 @@ static void mptcp_pm_nl_fullmesh(struct mptcp_sock *msk,
 	list.ids[list.nr++] = mptcp_endp_get_local_id(msk, addr);
 
 	spin_lock_bh(&msk->pm.lock);
-	mptcp_pm_nl_rm_subflow_received(msk, &list);
+	mptcp_pm_rm_subflow(msk, &list);
 	__mark_subflow_endp_available(msk, list.ids[0]);
 	mptcp_pm_create_subflow_or_signal_addr(msk);
 	spin_unlock_bh(&msk->pm.lock);
-- 
2.53.0