netdev - [PATCH AUTOSEL 6.11 038/244] l2tp: use rcu list add/del when updating lists

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Message-ID: <20240925113641.1297102-38-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:24:19 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: James Chapman <jchapman@...alix.com>,
	Tom Parkin <tparkin@...alix.com>,
	"David S . Miller" <davem@...emloft.net>,
	Sasha Levin <sashal@...nel.org>,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	samuel.thibault@...-lyon.org,
	thorsten.blum@...lux.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.11 038/244] l2tp: use rcu list add/del when updating lists

From: James Chapman <jchapman@...alix.com>

[ Upstream commit 89b768ec2dfefaeba5212de14fc71368e12d06ba ]

l2tp_v3_session_htable and tunnel->session_list are read by lockless
getters using RCU. Use rcu list variants when adding or removing list
items.

Signed-off-by: James Chapman <jchapman@...alix.com>
Signed-off-by: Tom Parkin <tparkin@...alix.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/l2tp/l2tp_core.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index edff7afc06199..ee8133f77b64c 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -394,12 +394,12 @@ static int l2tp_session_collision_add(struct l2tp_net *pn,
 
 	/* If existing session isn't already in the session hlist, add it. */
 	if (!hash_hashed(&session2->hlist))
-		hash_add(pn->l2tp_v3_session_htable, &session2->hlist,
-			 session2->hlist_key);
+		hash_add_rcu(pn->l2tp_v3_session_htable, &session2->hlist,
+			     session2->hlist_key);
 
 	/* Add new session to the hlist and collision list */
-	hash_add(pn->l2tp_v3_session_htable, &session1->hlist,
-		 session1->hlist_key);
+	hash_add_rcu(pn->l2tp_v3_session_htable, &session1->hlist,
+		     session1->hlist_key);
 	refcount_inc(&clist->ref_count);
 	l2tp_session_coll_list_add(clist, session1);
 
@@ -415,7 +415,7 @@ static void l2tp_session_collision_del(struct l2tp_net *pn,
 
 	lockdep_assert_held(&pn->l2tp_session_idr_lock);
 
-	hash_del(&session->hlist);
+	hash_del_rcu(&session->hlist);
 
 	if (clist) {
 		/* Remove session from its collision list. If there
@@ -490,7 +490,7 @@ int l2tp_session_register(struct l2tp_session *session,
 
 	l2tp_tunnel_inc_refcount(tunnel);
 	WRITE_ONCE(session->tunnel, tunnel);
-	list_add(&session->list, &tunnel->session_list);
+	list_add_rcu(&session->list, &tunnel->session_list);
 
 	if (tunnel->version == L2TP_HDR_VER_3) {
 		if (!other_session)
-- 
2.43.0