linux-kernel - [PATCH 4.2.y-ckt 247/273] l2tp: Fix error creating L2TP tunnels

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Date:	Mon,  7 Mar 2016 14:50:38 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>,
	"David S . Miller" <davem@...emloft.net>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 247/273] l2tp: Fix error creating L2TP tunnels

4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>

[ Upstream commit 853effc55b0f975abd6d318cca486a9c1b67e10f ]

A previous commit (33f72e6) added notification via netlink for tunnels
when created/modified/deleted. If the notification returned an error,
this error was returned from the tunnel function. If there were no
listeners, the error code ESRCH was returned, even though having no
listeners is not an error. Other calls to this and other similar
notification functions either ignore the error code, or filter ESRCH.
This patch checks for ESRCH and does not flag this as an error.

Reviewed-by: Hamish Martin <hamish.martin@...iedtelesis.co.nz>
Signed-off-by: Mark Tomlinson <mark.tomlinson@...iedtelesis.co.nz>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 net/l2tp/l2tp_netlink.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index 9e13c2f..fe92a08 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -124,8 +124,13 @@ static int l2tp_tunnel_notify(struct genl_family *family,
 	ret = l2tp_nl_tunnel_send(msg, info->snd_portid, info->snd_seq,
 				  NLM_F_ACK, tunnel, cmd);
 
-	if (ret >= 0)
-		return genlmsg_multicast_allns(family, msg, 0,	0, GFP_ATOMIC);
+	if (ret >= 0) {
+		ret = genlmsg_multicast_allns(family, msg, 0, 0, GFP_ATOMIC);
+		/* We don't care if no one is listening */
+		if (ret == -ESRCH)
+			ret = 0;
+		return ret;
+	}
 
 	nlmsg_free(msg);
 
@@ -147,8 +152,13 @@ static int l2tp_session_notify(struct genl_family *family,
 	ret = l2tp_nl_session_send(msg, info->snd_portid, info->snd_seq,
 				   NLM_F_ACK, session, cmd);
 
-	if (ret >= 0)
-		return genlmsg_multicast_allns(family, msg, 0,	0, GFP_ATOMIC);
+	if (ret >= 0) {
+		ret = genlmsg_multicast_allns(family, msg, 0, 0, GFP_ATOMIC);
+		/* We don't care if no one is listening */
+		if (ret == -ESRCH)
+			ret = 0;
+		return ret;
+	}
 
 	nlmsg_free(msg);
 
-- 
2.7.0