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Date: Tue, 13 Feb 2018 12:54:47 +0200
From: Eyal Birger <eyal.birger@...il.com>
To: steffen.klassert@...unet.com
Cc: herbert@...dor.apana.org.au, weiwan@...gle.com,
davem@...emloft.net, netdev@...r.kernel.org, fw@...len.de,
shmulik@...anetworks.com, shannon.nelson@...cle.com,
Eyal Birger <eyal.birger@...il.com>
Subject: [PATCH ipsec,v3] net: xfrm_policy: fix device unregistration hang
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.
This issue was first introduced in commit 52df157f17e5
("xfrm: take refcnt of dst when creating struct xfrm_dst bundle")
as part of an effort to remove routing garbage collection.
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/down events.
Signed-off-by: Eyal Birger <eyal.birger@...il.com>
Fixes: 52df157f17e5 ("xfrm: take refcnt of dst when creating struct xfrm_dst bundle")
[1] https://patchwork.ozlabs.org/patch/869025/
---
v3:
- add 'Fixes' tag and document appropriately
v2:
- call gc flush from existing netdev notifier per Shannon Nelson's
suggestion.
---
include/net/xfrm.h | 11 +++------
net/xfrm/xfrm_device.c | 2 ++
net/xfrm/xfrm_policy.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 72 insertions(+), 7 deletions(-)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 7d20776..4614047 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -324,6 +324,7 @@ void xfrm_policy_unregister_afinfo(const struct xfrm_policy_afinfo *afinfo);
void km_policy_notify(struct xfrm_policy *xp, int dir,
const struct km_event *c);
void xfrm_policy_cache_flush(void);
+void xfrm_policy_dst_gc_flush_dev(struct net_device *dev);
void km_state_notify(struct xfrm_state *x, const struct km_event *c);
struct xfrm_tmpl;
@@ -994,6 +995,8 @@ 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 +1028,7 @@ 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_device.c b/net/xfrm/xfrm_device.c
index 8e70291..5bd9892 100644
--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -309,6 +309,7 @@ static int xfrm_dev_register(struct net_device *dev)
static int xfrm_dev_unregister(struct net_device *dev)
{
xfrm_policy_cache_flush();
+ xfrm_policy_dst_gc_flush_dev(dev);
return NOTIFY_DONE;
}
@@ -323,6 +324,7 @@ static int xfrm_dev_down(struct net_device *dev)
xfrm_dev_state_flush(dev_net(dev), dev, true);
xfrm_policy_cache_flush();
+ xfrm_policy_dst_gc_flush_dev(dev);
return NOTIFY_DONE;
}
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 7a23078..c7b9a9a 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);
+
+void xfrm_policy_dst_gc_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
@@ -2984,6 +3037,18 @@ 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);
+ }
+}
+
void __init xfrm_init(void)
{
int i;
@@ -2998,6 +3063,7 @@ 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
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