In setups like the following:
Host A -- Host B
tun0 -- ipsec -- eth0 -- eth0 -- ipsec -- tun0
where tun0 are tunnel devices using dst_cache (ipip, ipip6, etc...).
Unregistration of an underlying eth0 device leads to the following log
messages:
unregister_netdevice: waiting for eth0 to become free. Usage count = 2
This is since xfrm dsts device references are not released upon device
unregistration when the xfrm dst is cached in a dst_cache.
Several approaches for fixing this were discussed in [1]; this commit keeps
track of allocated xdsts and releases their device references on a netdev
unregister event.
Signed-off-by: Eyal Birger <eyal.bir...@gmail.com>
[1] https://patchwork.ozlabs.org/patch/869025/
---
include/net/xfrm.h | 10 ++-----
net/xfrm/xfrm_policy.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 7 deletions(-)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 7d20776..c1c8493 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -994,6 +994,8 @@ struct xfrm_dst {
u32 child_mtu_cached;
u32 route_cookie;
u32 path_cookie;
+ struct list_head xfrm_dst_gc;
+ struct xfrm_dst_list *xfrm_dst_gc_list;
};
static inline struct dst_entry *xfrm_dst_path(const struct dst_entry *dst)
@@ -1025,13 +1027,7 @@ static inline void xfrm_dst_set_child(struct xfrm_dst
*xdst, struct dst_entry *c
xdst->child = child;
}
-static inline void xfrm_dst_destroy(struct xfrm_dst *xdst)
-{
- xfrm_pols_put(xdst->pols, xdst->num_pols);
- dst_release(xdst->route);
- if (likely(xdst->u.dst.xfrm))
- xfrm_state_put(xdst->u.dst.xfrm);
-}
+void xfrm_dst_destroy(struct xfrm_dst *xdst);
#endif
void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev);
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 7a23078..1da8a65 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -45,6 +45,12 @@ struct xfrm_flo {
u8 flags;
};
+struct xfrm_dst_list {
+ spinlock_t lock; /* sync writers */
+ struct list_head head;
+};
+
+static DEFINE_PER_CPU_ALIGNED(struct xfrm_dst_list, xfrm_dst_gc_list);
static DEFINE_PER_CPU(struct xfrm_dst *, xfrm_last_dst);
static struct work_struct *xfrm_pcpu_work __read_mostly;
static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
@@ -94,6 +100,51 @@ __xfrm6_selector_match(const struct xfrm_selector *sel,
const struct flowi *fl)
(fl6->flowi6_oif == sel->ifindex || !sel->ifindex);
}
+static void xfrm_dst_add_to_gc_list(struct xfrm_dst *xdst)
+{
+ struct xfrm_dst_list *xl = raw_cpu_ptr(&xfrm_dst_gc_list);
+
+ xdst->xfrm_dst_gc_list = xl;
+
+ spin_lock_bh(&xl->lock);
+ list_add_tail(&xdst->xfrm_dst_gc, &xl->head);
+ spin_unlock_bh(&xl->lock);
+}
+
+void xfrm_dst_destroy(struct xfrm_dst *xdst)
+{
+ xfrm_pols_put(xdst->pols, xdst->num_pols);
+ dst_release(xdst->route);
+ if (likely(xdst->u.dst.xfrm))
+ xfrm_state_put(xdst->u.dst.xfrm);
+ if (!list_empty(&xdst->xfrm_dst_gc)) {
+ struct xfrm_dst_list *xl = xdst->xfrm_dst_gc_list;
+
+ spin_lock_bh(&xl->lock);
+ list_del(&xdst->xfrm_dst_gc);
+ spin_unlock_bh(&xl->lock);
+ }
+}
+EXPORT_SYMBOL_GPL(xfrm_dst_destroy);
+
+static void xfrm_flush_dev(struct net_device *dev)
+{
+ struct xfrm_dst *xdst;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct xfrm_dst_list *xl = &per_cpu(xfrm_dst_gc_list, cpu);
+
+ spin_lock_bh(&xl->lock);
+ list_for_each_entry(xdst, &xl->head, xfrm_dst_gc) {
+ if (xdst->u.dst.dev != dev)
+ continue;
+ dst_dev_put(&xdst->u.dst);
+ }
+ spin_unlock_bh(&xl->lock);
+ }
+}
+
bool xfrm_selector_match(const struct xfrm_selector *sel, const struct flowi
*fl,
unsigned short family)
{
@@ -1581,6 +1632,8 @@ static struct dst_entry *xfrm_bundle_create(struct
xfrm_policy *policy,
}
bundle[i] = xdst;
+ xfrm_dst_add_to_gc_list(xdst);
+
if (!xdst_prev)
xdst0 = xdst;
else
@@ -2937,6 +2990,20 @@ static void xfrm_policy_fini(struct net *net)
xfrm_hash_free(net->xfrm.policy_byidx, sz);
}
+static int xfrm_netdev_event(struct notifier_block *this, unsigned long event,
+ void *ptr)
+{
+ struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+ if (event == NETDEV_UNREGISTER)
+ xfrm_flush_dev(dev);
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block xfrm_netdev_notifier = {
+ .notifier_call = xfrm_netdev_event,
+};
+
static int __net_init xfrm_net_init(struct net *net)
{
int rv;
@@ -2984,6 +3051,19 @@ static struct pernet_operations __net_initdata
xfrm_net_ops = {
.exit = xfrm_net_exit,
};
+static void __init xfrm_dst_gc_init(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct xfrm_dst_list *xl = &per_cpu(xfrm_dst_gc_list, cpu);
+
+ INIT_LIST_HEAD(&xl->head);
+ spin_lock_init(&xl->lock);
+ }
+ register_netdevice_notifier(&xfrm_netdev_notifier);
+}
+
void __init xfrm_init(void)
{
int i;
@@ -2998,6 +3078,7 @@ void __init xfrm_init(void)
register_pernet_subsys(&xfrm_net_ops);
seqcount_init(&xfrm_policy_hash_generation);
xfrm_input_init();
+ xfrm_dst_gc_init();
}
#ifdef CONFIG_AUDITSYSCALL
--
2.7.4
