linux-kernel - [PATCH 3.12 03/98] ipv4: Don't do expensive useless work during inetdev destroy.

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Date:	Mon, 11 Apr 2016 15:22:05 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 03/98] ipv4: Don't do expensive useless work during inetdev destroy.

From: "David S. Miller" <davem@...emloft.net>

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

===============

commit fbd40ea0180a2d328c5adc61414dc8bab9335ce2 upstream.

When an inetdev is destroyed, every address assigned to the interface
is removed.  And in this scenerio we do two pointless things which can
be very expensive if the number of assigned interfaces is large:

1) Address promotion.  We are deleting all addresses, so there is no
   point in doing this.

2) A full nf conntrack table purge for every address.  We only need to
   do this once, as is already caught by the existing
   masq_dev_notifier so masq_inet_event() can skip this.

[mk] 3.12.*: The change in masq_inet_event() needs to be duplicated in
both IPv4 and IPv6 version of the function, these two were merged in
3.18.

Reported-by: Solar Designer <solar@...nwall.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Tested-by: Cyrill Gorcunov <gorcunov@...nvz.org>
Acked-by: Michal Kubecek <mkubecek@...e.cz>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 net/ipv4/devinet.c                   |  4 ++++
 net/ipv4/fib_frontend.c              |  4 ++++
 net/ipv4/netfilter/ipt_MASQUERADE.c  | 12 ++++++++++--
 net/ipv6/netfilter/ip6t_MASQUERADE.c | 12 ++++++++++--
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 68447109000f..6678bebb82c8 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -328,6 +328,9 @@ static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 
 	ASSERT_RTNL();
 
+	if (in_dev->dead)
+		goto no_promotions;
+
 	/* 1. Deleting primary ifaddr forces deletion all secondaries
 	 * unless alias promotion is set
 	 **/
@@ -374,6 +377,7 @@ static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 			fib_del_ifaddr(ifa, ifa1);
 	}
 
+no_promotions:
 	/* 2. Unlink it */
 
 	*ifap = ifa1->ifa_next;
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index f7f8cff67344..25a0946f7074 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -812,6 +812,9 @@ void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)
 		subnet = 1;
 	}
 
+	if (in_dev->dead)
+		goto no_promotions;
+
 	/* Deletion is more complicated than add.
 	 * We should take care of not to delete too much :-)
 	 *
@@ -887,6 +890,7 @@ void fib_del_ifaddr(struct in_ifaddr *ifa, struct in_ifaddr *iprim)
 		}
 	}
 
+no_promotions:
 	if (!(ok & BRD_OK))
 		fib_magic(RTM_DELROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32, prim);
 	if (subnet && ifa->ifa_prefixlen < 31) {
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
index 00352ce0f0de..3bc1c98aa2f0 100644
--- a/net/ipv4/netfilter/ipt_MASQUERADE.c
+++ b/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -128,10 +128,18 @@ static int masq_inet_event(struct notifier_block *this,
 			   unsigned long event,
 			   void *ptr)
 {
-	struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
+	struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev;
 	struct netdev_notifier_info info;
 
-	netdev_notifier_info_init(&info, dev);
+	/* The masq_dev_notifier will catch the case of the device going
+	 * down.  So if the inetdev is dead and being destroyed we have
+	 * no work to do.  Otherwise this is an individual address removal
+	 * and we have to perform the flush.
+	 */
+	if (idev->dead)
+		return NOTIFY_DONE;
+
+	netdev_notifier_info_init(&info, idev->dev);
 	return masq_device_event(this, event, &info);
 }
 
diff --git a/net/ipv6/netfilter/ip6t_MASQUERADE.c b/net/ipv6/netfilter/ip6t_MASQUERADE.c
index 3e4e92d5e157..bee09e9050c3 100644
--- a/net/ipv6/netfilter/ip6t_MASQUERADE.c
+++ b/net/ipv6/netfilter/ip6t_MASQUERADE.c
@@ -88,10 +88,18 @@ static struct notifier_block masq_dev_notifier = {
 static int masq_inet_event(struct notifier_block *this,
 			   unsigned long event, void *ptr)
 {
-	struct inet6_ifaddr *ifa = ptr;
+	struct inet6_dev *idev = ((struct inet6_ifaddr *)ptr)->idev;
 	struct netdev_notifier_info info;
 
-	netdev_notifier_info_init(&info, ifa->idev->dev);
+	/* The masq_dev_notifier will catch the case of the device going
+	 * down.  So if the inetdev is dead and being destroyed we have
+	 * no work to do.  Otherwise this is an individual address removal
+	 * and we have to perform the flush.
+	 */
+	if (idev->dead)
+		return NOTIFY_DONE;
+
+	netdev_notifier_info_init(&info, idev->dev);
 	return masq_device_event(this, event, &info);
 }
 
-- 
2.8.1