Re: [RFC] net: ipv4 -- Introduce ifa limit per net

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 04 Mar 2016 16:08:30 -0800

> __inet_del_ifa() should probably take into account in_dev->dead (no
> promotion, no list scan...)

Indeed, that is the real problem:

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 8c3df2c..7412feb 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -334,6 +334,12 @@ static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 
 	ASSERT_RTNL();
 
+	/* None of these potentially quadratic scans matter if the
+	 * device is being destroyed.
+	 */
+	if (in_dev->dead)
+		goto no_promotions;
+
 	/* 1. Deleting primary ifaddr forces deletion all secondaries
 	 * unless alias promotion is set
 	 **/
@@ -380,6 +386,7 @@ 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;