netdev - [PATCH net-next 3/3] l2tp: remove the .tunnel_sock field from struct pppol2tp

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Date:   Sat, 11 Nov 2017 06:06:37 +0900
From:   Guillaume Nault <g.nault@...halink.fr>
To:     netdev@...r.kernel.org
Cc:     James Chapman <jchapman@...alix.com>
Subject: [PATCH net-next 3/3] l2tp: remove the .tunnel_sock field from struct
 pppol2tp_session

The last user of .tunnel_sock is pppol2tp_connect() which defensively
uses it to verify internal data consistency.

This check isn't necessary: l2tp_session_get() guarantees that the
returned session belongs to the tunnel passed as parameter. And
.tunnel_sock is never updated, so checking that it still points to
the parent tunnel socket is useless; that test can never fail.

Signed-off-by: Guillaume Nault <g.nault@...halink.fr>
---
 net/l2tp/l2tp_ppp.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 88b4cb1b7cde..b412fc3351dc 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -127,8 +127,6 @@ struct pppol2tp_session {
 						 * PPPoX socket */
 	struct sock		*__sk;		/* Copy of .sk, for cleanup */
 	struct rcu_head		rcu;		/* For asynchronous release */
-	struct sock		*tunnel_sock;	/* Pointer to the tunnel UDP
-						 * socket */
 	int			flags;		/* accessed by PPPIOCGFLAGS.
 						 * Unused. */
 };
@@ -592,7 +590,6 @@ static void pppol2tp_session_init(struct l2tp_session *session)
 
 	ps = l2tp_session_priv(session);
 	mutex_init(&ps->sk_lock);
-	ps->tunnel_sock = session->tunnel->sock;
 	ps->owner = current->pid;
 
 	/* If PMTU discovery was enabled, use the MTU that was discovered */
@@ -743,13 +740,6 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 			error = -EEXIST;
 			goto end;
 		}
-
-		/* consistency checks */
-		if (ps->tunnel_sock != tunnel->sock) {
-			mutex_unlock(&ps->sk_lock);
-			error = -EEXIST;
-			goto end;
-		}
 	} else {
 		/* Default MTU must allow space for UDP/L2TP/PPP headers */
 		cfg.mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD;
-- 
2.11.0