netdev - [PATCH net-next 09/15] l2tp: free sessions using rcu

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Message-Id: <1d9c903d17d8ec6e1e4f8a674693526a14a904ee.1722265212.git.jchapman@katalix.com>
Date: Mon, 29 Jul 2024 16:38:08 +0100
From: James Chapman <jchapman@...alix.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	dsahern@...nel.org,
	tparkin@...alix.com
Subject: [PATCH net-next 09/15] l2tp: free sessions using rcu

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>
---
 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 f6ae18c180bf..4cf4aa271353 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -166,7 +166,7 @@ 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(const struct sock *sk)
@@ -1269,8 +1269,6 @@ 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 8d7a589ccd2a..58d3977870de 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -66,6 +66,7 @@ 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;
-- 
2.34.1