xfrm: reuse uncached_list to track xdsts

BugLink: http://bugs.launchpad.net/bugs/1746474
In early time, when freeing a xdst, it would be inserted into
dst_garbage.list first. Then if it's refcnt was still held
somewhere, later it would be put into dst_busy_list in
dst_gc_task().

When one dev was being unregistered, the dev of these dsts in
dst_busy_list would be set with loopback_dev and put this dev.
So that this dev's removal wouldn't get blocked, and avoid the
kmsg warning:

  kernel:unregister_netdevice: waiting for veth0 to become \
  free. Usage count = 2

However after Commit 52df157f17e5 ("xfrm: take refcnt of dst
when creating struct xfrm_dst bundle"), the xdst will not be
freed with dst gc, and this warning happens.

To fix it, we need to find these xdsts that are still held by
others when removing the dev, and free xdst's dev and set it
with loopback_dev.

But unfortunately after flow_cache for xfrm was deleted, no
list tracks them anymore. So we need to save these xdsts
somewhere to release the xdst's dev later.

To make this easier, this patch is to reuse uncached_list to
track xdsts, so that the dev refcnt can be released in the
event NETDEV_UNREGISTER process of fib_netdev_notifier.

Thanks to Florian, we could move forward this fix quickly.

Fixes: 52df157f17e5 ("xfrm: take refcnt of dst when creating struct xfrm_dst bundle")
Reported-by: Jianlin Shi <jishi@redhat.com>
Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Tested-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
(back ported from commit 510c321b557121861601f9d259aadd65aa274f35)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: AceLan Kao <acelan.kao@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 199056933dcbf44cf25c00619cf4af8db66997da..7721693e62094f8219b29955a3a3b4e677cbf6c9 100644 (file)
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -163,6 +163,8 @@ void rt6_mtu_change(struct net_device *dev, unsigned int mtu);
 void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
 void rt6_clean_tohost(struct net *net, struct in6_addr *gateway);
 
+void rt6_uncached_list_add(struct rt6_info *rt);
+void rt6_uncached_list_del(struct rt6_info *rt);
 
 /*
  *     Store a destination cache entry in a socket

diff --git a/include/net/route.h b/include/net/route.h
index 58458966e31e7adf0e720d658a2db51bbaed0512..09a3507ca5df3ae329bdc653410f0609a6e3eeb4 100644 (file)
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -226,6 +226,9 @@ struct in_ifaddr;
 void fib_add_ifaddr(struct in_ifaddr *);
 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
 
+void rt_add_uncached_list(struct rtable *rt);
+void rt_del_uncached_list(struct rtable *rt);
+
 static inline void ip_rt_put(struct rtable *rt)
 {
        /* dst_release() accepts a NULL parameter.

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 83a2c49487b8a508376159770d470de6c97a5558..33db041156d81216ea3f3338910690ac89622c56 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1382,7 +1382,7 @@ struct uncached_list {
 
 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
 
-static void rt_add_uncached_list(struct rtable *rt)
+void rt_add_uncached_list(struct rtable *rt)
 {
        struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
 
@@ -1393,14 +1393,8 @@ static void rt_add_uncached_list(struct rtable *rt)
        spin_unlock_bh(&ul->lock);
 }
 
-static void ipv4_dst_destroy(struct dst_entry *dst)
+void rt_del_uncached_list(struct rtable *rt)
 {
-       struct dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);
-       struct rtable *rt = (struct rtable *) dst;
-
-       if (p != &dst_default_metrics && refcount_dec_and_test(&p->refcnt))
-               kfree(p);
-
        if (!list_empty(&rt->rt_uncached)) {
                struct uncached_list *ul = rt->rt_uncached_list;
 
@@ -1410,6 +1404,17 @@ static void ipv4_dst_destroy(struct dst_entry *dst)
        }
 }
 
+static void ipv4_dst_destroy(struct dst_entry *dst)
+{
+       struct dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);
+       struct rtable *rt = (struct rtable *)dst;
+
+       if (p != &dst_default_metrics && refcount_dec_and_test(&p->refcnt))
+               kfree(p);
+
+       rt_del_uncached_list(rt);
+}
+
 void rt_flush_dev(struct net_device *dev)
 {
        struct net *net = dev_net(dev);

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 71b4ecc195c707b3e2ce9dab974f6d68a5e5c5eb..cb9890ab3bd4f4f1d1cb1949ea8c8f335a795eb5 100644 (file)
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -97,6 +97,7 @@ static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
        xdst->u.rt.rt_pmtu = rt->rt_pmtu;
        xdst->u.rt.rt_table_id = rt->rt_table_id;
        INIT_LIST_HEAD(&xdst->u.rt.rt_uncached);
+       rt_add_uncached_list(&xdst->u.rt);
 
        return 0;
 }
@@ -244,7 +245,8 @@ static void xfrm4_dst_destroy(struct dst_entry *dst)
        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 
        dst_destroy_metrics_generic(dst);
-
+       if (xdst->u.rt.rt_uncached_list)
+               rt_del_uncached_list(&xdst->u.rt);
        xfrm_dst_destroy(xdst);
 }
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index d00e41c3786e8e3505e243777e366c8a407bf4e6..6062c654b02faae811c9632fd4213fde461d177e 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -124,7 +124,7 @@ struct uncached_list {
 
 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt6_uncached_list);
 
-static void rt6_uncached_list_add(struct rt6_info *rt)
+void rt6_uncached_list_add(struct rt6_info *rt)
 {
        struct uncached_list *ul = raw_cpu_ptr(&rt6_uncached_list);
 
@@ -135,7 +135,7 @@ static void rt6_uncached_list_add(struct rt6_info *rt)
        spin_unlock_bh(&ul->lock);
 }
 
-static void rt6_uncached_list_del(struct rt6_info *rt)
+void rt6_uncached_list_del(struct rt6_info *rt)
 {
        if (!list_empty(&rt->rt6i_uncached)) {
                struct uncached_list *ul = rt->rt6i_uncached_list;

diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 79651bc71bf0d48d54e47d75cef0cd3f686e16ab..dec840c8b4b460755c43370d70b750463872757c 100644 (file)
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -109,6 +109,8 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
        xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
        xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
        xdst->u.rt6.rt6i_src = rt->rt6i_src;
+       INIT_LIST_HEAD(&xdst->u.rt6.rt6i_uncached);
+       rt6_uncached_list_add(&xdst->u.rt6);
 
        return 0;
 }
@@ -247,6 +249,8 @@ static void xfrm6_dst_destroy(struct dst_entry *dst)
        if (likely(xdst->u.rt6.rt6i_idev))
                in6_dev_put(xdst->u.rt6.rt6i_idev);
        dst_destroy_metrics_generic(dst);
+       if (xdst->u.rt6.rt6i_uncached_list)
+               rt6_uncached_list_del(&xdst->u.rt6);
        xfrm_dst_destroy(xdst);
 }