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

Sasha Levin
2024-09-25T11:38:04Z

From: James Chapman <jchapman@katalix.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@katalix.com>
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.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