[PATCH net-next 10/16] l2tp: add session_free callback

[James Chapman <jchapman@katalix.com>]

When a session refcount hits 0, the session is freed via
l2tp_session_free. Some pseudowires (ppp, eth) may have additional
resources to free when this happens. Add a session_free callback that
can be used by pseudowires to override the default kfree. The callback
is responsible for freeing the session.

Signed-off-by: James Chapman <jchapman@katalix.com>
---
 net/l2tp/l2tp_core.c | 7 +++++--
 net/l2tp/l2tp_core.h | 1 +
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 869dec89ff0f..d6306ba2d78e 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1662,12 +1662,15 @@ void l2tp_session_free(struct l2tp_session *session)
 
 	BUG_ON(refcount_read(&session->ref_count) != 0);
 
+	if (session->session_free)
+		session->session_free(session);
+	else
+		kfree(session);
+
 	if (tunnel) {
 		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
 		l2tp_tunnel_dec_refcount(tunnel);
 	}
-
-	kfree(session);
 }
 EXPORT_SYMBOL_GPL(l2tp_session_free);
 
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 98709086fe84..be3fa986dfd1 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -125,6 +125,7 @@ struct l2tp_session {
 	int (*build_header)(struct l2tp_session *session, void *buf);
 	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 	void (*session_close)(struct l2tp_session *session);
+	void (*session_free)(struct l2tp_session *session);
 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 	void (*show)(struct seq_file *m, void *priv);
 #endif
-- 
1.9.1