linux-kernel - [PATCH 3.2 14/79] l2tp: add session reorder queue purge function to core

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Message-ID: <lsq.1518322806.699914069@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Tom Parkin" <tparkin@...alix.com>,
        "James Chapman" <jchapman@...alix.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.2 14/79] l2tp: add session reorder queue purge function
 to core

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Parkin <tparkin@...alix.com>

commit 48f72f92b31431c40279b0fba6c5588e07e67d95 upstream.

If an l2tp session is deleted, it is necessary to delete skbs in-flight
on the session's reorder queue before taking it down.

Rather than having each pseudowire implementation reaching into the
l2tp_session struct to handle this itself, provide a function in l2tp_core to
purge the session queue.

Signed-off-by: Tom Parkin <tparkin@...alix.com>
Signed-off-by: James Chapman <jchapman@...alix.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.2: use non-atomic increment on rx_errors]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/l2tp/l2tp_core.c | 17 +++++++++++++++++
 net/l2tp/l2tp_core.h |  1 +
 2 files changed, 18 insertions(+)

--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -830,6 +830,23 @@ discard:
 }
 EXPORT_SYMBOL(l2tp_recv_common);
 
+/* Drop skbs from the session's reorder_q
+ */
+int l2tp_session_queue_purge(struct l2tp_session *session)
+{
+	struct sk_buff *skb = NULL;
+	BUG_ON(!session);
+	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+	while ((skb = skb_dequeue(&session->reorder_q))) {
+		session->stats.rx_errors++;
+		kfree_skb(skb);
+		if (session->deref)
+			(*session->deref)(session);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
+
 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
  * here. The skb is not on a list when we get here.
  * Returns 0 if the packet was a data packet and was successfully passed on.
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -249,6 +249,7 @@ extern struct l2tp_session *l2tp_session
 extern int l2tp_session_delete(struct l2tp_session *session);
 extern void l2tp_session_free(struct l2tp_session *session);
 extern void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, unsigned char *ptr, unsigned char *optr, u16 hdrflags, int length, int (*payload_hook)(struct sk_buff *skb));
+extern int l2tp_session_queue_purge(struct l2tp_session *session);
 extern int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
 
 extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len);