linux-kernel - [PATCH AUTOSEL 6.11 037/244] l2tp: free sessions using rcu

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Message-ID: <20240925113641.1297102-37-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:24:18 -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 6.11 037/244] l2tp: free sessions using rcu

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

[ Upstream commit d17e89999574aca143dd4ede43e4382d32d98724 ]

l2tp sessions may be accessed under an rcu read lock. Have them freed
via rcu and remove the now unneeded synchronize_rcu when a session is
removed.

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 | 4 +---
 net/l2tp/l2tp_core.h | 1 +
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index a9cbcbc9d016d..edff7afc06199 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -152,7 +152,7 @@ static void l2tp_session_free(struct l2tp_session *session)
 	trace_free_session(session);
 	if (session->tunnel)
 		l2tp_tunnel_dec_refcount(session->tunnel);
-	kfree(session);
+	kfree_rcu(session, rcu);
 }
 
 struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk)
@@ -1298,8 +1298,6 @@ static void l2tp_session_unhash(struct l2tp_session *session)
 
 		spin_unlock_bh(&pn->l2tp_session_idr_lock);
 		spin_unlock_bh(&tunnel->list_lock);
-
-		synchronize_rcu();
 	}
 }
 
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 6c25c196cc222..d0e3460089d90 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -67,6 +67,7 @@ struct l2tp_session_coll_list {
 struct l2tp_session {
 	int			magic;		/* should be L2TP_SESSION_MAGIC */
 	long			dead;
+	struct rcu_head		rcu;
 
 	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel context */
 	u32			session_id;
-- 
2.43.0