linux-kernel - [062/146] igmp: call ip_mc_clear_src() only when we have no users of ip_mc

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Message-Id: <20110601080323.623873577@blue.kroah.org>
Date:	Wed, 01 Jun 2011 16:59:58 +0900
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	David L Stevens <dlstevens@...ibm.com>,
	Veaceslav Falico <vfalico@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [062/146] igmp: call ip_mc_clear_src() only when we have no users of ip_mc_list

2.6.38-stable review patch.  If anyone has any objections, please let us know.

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


From: Veaceslav Falico <vfalico@...hat.com>

[ Upstream commit 24cf3af3fed5edcf90bc2a0ed181e6ce1513d2dc ]

In igmp_group_dropped() we call ip_mc_clear_src(), which resets the number
of source filters per mulitcast. However, igmp_group_dropped() is also
called on NETDEV_DOWN, NETDEV_PRE_TYPE_CHANGE and NETDEV_UNREGISTER, which
means that the group might get added back on NETDEV_UP, NETDEV_REGISTER and
NETDEV_POST_TYPE_CHANGE respectively, leaving us with broken source
filters.

To fix that, we must clear the source filters only when there are no users
in the ip_mc_list, i.e. in ip_mc_dec_group() and on device destroy.

Acked-by: David L Stevens <dlstevens@...ibm.com>
Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 net/ipv4/igmp.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1172,20 +1172,18 @@ static void igmp_group_dropped(struct ip
 
 	if (!in_dev->dead) {
 		if (IGMP_V1_SEEN(in_dev))
-			goto done;
+			return;
 		if (IGMP_V2_SEEN(in_dev)) {
 			if (reporter)
 				igmp_send_report(in_dev, im, IGMP_HOST_LEAVE_MESSAGE);
-			goto done;
+			return;
 		}
 		/* IGMPv3 */
 		igmpv3_add_delrec(in_dev, im);
 
 		igmp_ifc_event(in_dev);
 	}
-done:
 #endif
-	ip_mc_clear_src(im);
 }
 
 static void igmp_group_added(struct ip_mc_list *im)
@@ -1322,6 +1320,7 @@ void ip_mc_dec_group(struct in_device *i
 				*ip = i->next_rcu;
 				in_dev->mc_count--;
 				igmp_group_dropped(i);
+				ip_mc_clear_src(i);
 
 				if (!in_dev->dead)
 					ip_rt_multicast_event(in_dev);
@@ -1431,7 +1430,8 @@ void ip_mc_destroy_dev(struct in_device
 		in_dev->mc_list = i->next_rcu;
 		in_dev->mc_count--;
 
-		igmp_group_dropped(i);
+		/* We've dropped the groups in ip_mc_down already */
+		ip_mc_clear_src(i);
 		ip_ma_put(i);
 	}
 }


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