Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next

Steffen Klassert says:

====================
ipsec-next 2016-09-08

1) Constify the xfrm_replay structures. From Julia Lawall

2) Protect xfrm state hash tables with rcu, lookups
   can be done now without acquiring xfrm_state_lock.
   From Florian Westphal.

3) Protect xfrm policy hash tables with rcu, lookups
   can be done now without acquiring xfrm_policy_lock.
   From Florian Westphal.

4) We don't need to have a garbage collector list per
   namespace anymore, so use a global one instead.
   From Florian Westphal.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 167 insertions, 105 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index b5e665b3cfb0..f7ce6265961a 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -49,6 +49,7 @@ static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO]
 						__read_mostly;
 
 static struct kmem_cache *xfrm_dst_cache __read_mostly;
+static __read_mostly seqcount_t xfrm_policy_hash_generation;
 
 static void xfrm_init_pmtu(struct dst_entry *dst);
 static int stale_bundle(struct dst_entry *dst);
@@ -59,6 +60,11 @@ static void __xfrm_policy_link(struct xfrm_policy *pol, int dir);
 static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
 						int dir);
 
+static inline bool xfrm_pol_hold_rcu(struct xfrm_policy *policy)
+{
+	return atomic_inc_not_zero(&policy->refcnt);
+}
+
 static inline bool
 __xfrm4_selector_match(const struct xfrm_selector *sel, const struct flowi *fl)
 {
@@ -385,9 +391,11 @@ static struct hlist_head *policy_hash_bysel(struct net *net,
 	__get_hash_thresh(net, family, dir, &dbits, &sbits);
 	hash = __sel_hash(sel, family, hmask, dbits, sbits);
 
-	return (hash == hmask + 1 ?
-		&net->xfrm.policy_inexact[dir] :
-		net->xfrm.policy_bydst[dir].table + hash);
+	if (hash == hmask + 1)
+		return &net->xfrm.policy_inexact[dir];
+
+	return rcu_dereference_check(net->xfrm.policy_bydst[dir].table,
+		     lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash;
 }
 
 static struct hlist_head *policy_hash_direct(struct net *net,
@@ -403,7 +411,8 @@ static struct hlist_head *policy_hash_direct(struct net *net,
 	__get_hash_thresh(net, family, dir, &dbits, &sbits);
 	hash = __addr_hash(daddr, saddr, family, hmask, dbits, sbits);
 
-	return net->xfrm.policy_bydst[dir].table + hash;
+	return rcu_dereference_check(net->xfrm.policy_bydst[dir].table,
+		     lockdep_is_held(&net->xfrm.xfrm_policy_lock)) + hash;
 }
 
 static void xfrm_dst_hash_transfer(struct net *net,
@@ -426,14 +435,14 @@ redo:
 		h = __addr_hash(&pol->selector.daddr, &pol->selector.saddr,
 				pol->family, nhashmask, dbits, sbits);
 		if (!entry0) {
-			hlist_del(&pol->bydst);
-			hlist_add_head(&pol->bydst, ndsttable+h);
+			hlist_del_rcu(&pol->bydst);
+			hlist_add_head_rcu(&pol->bydst, ndsttable + h);
 			h0 = h;
 		} else {
 			if (h != h0)
 				continue;
-			hlist_del(&pol->bydst);
-			hlist_add_behind(&pol->bydst, entry0);
+			hlist_del_rcu(&pol->bydst);
+			hlist_add_behind_rcu(&pol->bydst, entry0);
 		}
 		entry0 = &pol->bydst;
 	}
@@ -468,22 +477,32 @@ static void xfrm_bydst_resize(struct net *net, int dir)
 	unsigned int hmask = net->xfrm.policy_bydst[dir].hmask;
 	unsigned int nhashmask = xfrm_new_hash_mask(hmask);
 	unsigned int nsize = (nhashmask + 1) * sizeof(struct hlist_head);
-	struct hlist_head *odst = net->xfrm.policy_bydst[dir].table;
 	struct hlist_head *ndst = xfrm_hash_alloc(nsize);
+	struct hlist_head *odst;
 	int i;
 
 	if (!ndst)
 		return;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
+	write_seqcount_begin(&xfrm_policy_hash_generation);
+
+	odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table,
+				lockdep_is_held(&net->xfrm.xfrm_policy_lock));
+
+	odst = rcu_dereference_protected(net->xfrm.policy_bydst[dir].table,
+				lockdep_is_held(&net->xfrm.xfrm_policy_lock));
 
 	for (i = hmask; i >= 0; i--)
 		xfrm_dst_hash_transfer(net, odst + i, ndst, nhashmask, dir);
 
-	net->xfrm.policy_bydst[dir].table = ndst;
+	rcu_assign_pointer(net->xfrm.policy_bydst[dir].table, ndst);
 	net->xfrm.policy_bydst[dir].hmask = nhashmask;
 
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	write_seqcount_end(&xfrm_policy_hash_generation);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
+
+	synchronize_rcu();
 
 	xfrm_hash_free(odst, (hmask + 1) * sizeof(struct hlist_head));
 }
@@ -500,7 +519,7 @@ static void xfrm_byidx_resize(struct net *net, int total)
 	if (!nidx)
 		return;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 
 	for (i = hmask; i >= 0; i--)
 		xfrm_idx_hash_transfer(oidx + i, nidx, nhashmask);
@@ -508,7 +527,7 @@ static void xfrm_byidx_resize(struct net *net, int total)
 	net->xfrm.policy_byidx = nidx;
 	net->xfrm.policy_idx_hmask = nhashmask;
 
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	xfrm_hash_free(oidx, (hmask + 1) * sizeof(struct hlist_head));
 }
@@ -541,7 +560,6 @@ static inline int xfrm_byidx_should_resize(struct net *net, int total)
 
 void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si)
 {
-	read_lock_bh(&net->xfrm.xfrm_policy_lock);
 	si->incnt = net->xfrm.policy_count[XFRM_POLICY_IN];
 	si->outcnt = net->xfrm.policy_count[XFRM_POLICY_OUT];
 	si->fwdcnt = net->xfrm.policy_count[XFRM_POLICY_FWD];
@@ -550,7 +568,6 @@ void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si)
 	si->fwdscnt = net->xfrm.policy_count[XFRM_POLICY_FWD+XFRM_POLICY_MAX];
 	si->spdhcnt = net->xfrm.policy_idx_hmask;
 	si->spdhmcnt = xfrm_policy_hashmax;
-	read_unlock_bh(&net->xfrm.xfrm_policy_lock);
 }
 EXPORT_SYMBOL(xfrm_spd_getinfo);
 
@@ -600,7 +617,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 		rbits6 = net->xfrm.policy_hthresh.rbits6;
 	} while (read_seqretry(&net->xfrm.policy_hthresh.lock, seq));
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 
 	/* reset the bydst and inexact table in all directions */
 	for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
@@ -642,7 +659,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 			hlist_add_head(&policy->bydst, chain);
 	}
 
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	mutex_unlock(&hash_resize_mutex);
 }
@@ -753,7 +770,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 	struct hlist_head *chain;
 	struct hlist_node *newpos;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	chain = policy_hash_bysel(net, &policy->selector, policy->family, dir);
 	delpol = NULL;
 	newpos = NULL;
@@ -764,7 +781,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 		    xfrm_sec_ctx_match(pol->security, policy->security) &&
 		    !WARN_ON(delpol)) {
 			if (excl) {
-				write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+				spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 				return -EEXIST;
 			}
 			delpol = pol;
@@ -800,7 +817,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 	policy->curlft.use_time = 0;
 	if (!mod_timer(&policy->timer, jiffies + HZ))
 		xfrm_pol_hold(policy);
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	if (delpol)
 		xfrm_policy_kill(delpol);
@@ -820,7 +837,7 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
 	struct hlist_head *chain;
 
 	*err = 0;
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	chain = policy_hash_bysel(net, sel, sel->family, dir);
 	ret = NULL;
 	hlist_for_each_entry(pol, chain, bydst) {
@@ -833,7 +850,7 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
 				*err = security_xfrm_policy_delete(
 								pol->security);
 				if (*err) {
-					write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+					spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 					return pol;
 				}
 				__xfrm_policy_unlink(pol, dir);
@@ -842,7 +859,7 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
 			break;
 		}
 	}
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	if (ret && delete)
 		xfrm_policy_kill(ret);
@@ -861,7 +878,7 @@ struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8 type,
 		return NULL;
 
 	*err = 0;
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	chain = net->xfrm.policy_byidx + idx_hash(net, id);
 	ret = NULL;
 	hlist_for_each_entry(pol, chain, byidx) {
@@ -872,7 +889,7 @@ struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8 type,
 				*err = security_xfrm_policy_delete(
 								pol->security);
 				if (*err) {
-					write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+					spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 					return pol;
 				}
 				__xfrm_policy_unlink(pol, dir);
@@ -881,7 +898,7 @@ struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8 type,
 			break;
 		}
 	}
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	if (ret && delete)
 		xfrm_policy_kill(ret);
@@ -939,7 +956,7 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
 {
 	int dir, err = 0, cnt = 0;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 
 	err = xfrm_policy_flush_secctx_check(net, type, task_valid);
 	if (err)
@@ -955,14 +972,14 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
 			if (pol->type != type)
 				continue;
 			__xfrm_policy_unlink(pol, dir);
-			write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+			spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 			cnt++;
 
 			xfrm_audit_policy_delete(pol, 1, task_valid);
 
 			xfrm_policy_kill(pol);
 
-			write_lock_bh(&net->xfrm.xfrm_policy_lock);
+			spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 			goto again1;
 		}
 
@@ -974,13 +991,13 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
 				if (pol->type != type)
 					continue;
 				__xfrm_policy_unlink(pol, dir);
-				write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+				spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 				cnt++;
 
 				xfrm_audit_policy_delete(pol, 1, task_valid);
 				xfrm_policy_kill(pol);
 
-				write_lock_bh(&net->xfrm.xfrm_policy_lock);
+				spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 				goto again2;
 			}
 		}
@@ -989,7 +1006,7 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
 	if (!cnt)
 		err = -ESRCH;
 out:
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 	return err;
 }
 EXPORT_SYMBOL(xfrm_policy_flush);
@@ -1009,7 +1026,7 @@ int xfrm_policy_walk(struct net *net, struct xfrm_policy_walk *walk,
 	if (list_empty(&walk->walk.all) && walk->seq != 0)
 		return 0;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	if (list_empty(&walk->walk.all))
 		x = list_first_entry(&net->xfrm.policy_all, struct xfrm_policy_walk_entry, all);
 	else
@@ -1037,7 +1054,7 @@ int xfrm_policy_walk(struct net *net, struct xfrm_policy_walk *walk,
 	}
 	list_del_init(&walk->walk.all);
 out:
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 	return error;
 }
 EXPORT_SYMBOL(xfrm_policy_walk);
@@ -1056,9 +1073,9 @@ void xfrm_policy_walk_done(struct xfrm_policy_walk *walk, struct net *net)
 	if (list_empty(&walk->walk.all))
 		return;
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock); /*FIXME where is net? */
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock); /*FIXME where is net? */
 	list_del(&walk->walk.all);
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 }
 EXPORT_SYMBOL(xfrm_policy_walk_done);
 
@@ -1096,17 +1113,24 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
 	struct xfrm_policy *pol, *ret;
 	const xfrm_address_t *daddr, *saddr;
 	struct hlist_head *chain;
-	u32 priority = ~0U;
+	unsigned int sequence;
+	u32 priority;
 
 	daddr = xfrm_flowi_daddr(fl, family);
 	saddr = xfrm_flowi_saddr(fl, family);
 	if (unlikely(!daddr || !saddr))
 		return NULL;
 
-	read_lock_bh(&net->xfrm.xfrm_policy_lock);
-	chain = policy_hash_direct(net, daddr, saddr, family, dir);
+	rcu_read_lock();
+ retry:
+	do {
+		sequence = read_seqcount_begin(&xfrm_policy_hash_generation);
+		chain = policy_hash_direct(net, daddr, saddr, family, dir);
+	} while (read_seqcount_retry(&xfrm_policy_hash_generation, sequence));
+
+	priority = ~0U;
 	ret = NULL;
-	hlist_for_each_entry(pol, chain, bydst) {
+	hlist_for_each_entry_rcu(pol, chain, bydst) {
 		err = xfrm_policy_match(pol, fl, type, family, dir);
 		if (err) {
 			if (err == -ESRCH)
@@ -1122,7 +1146,7 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
 		}
 	}
 	chain = &net->xfrm.policy_inexact[dir];
-	hlist_for_each_entry(pol, chain, bydst) {
+	hlist_for_each_entry_rcu(pol, chain, bydst) {
 		if ((pol->priority >= priority) && ret)
 			break;
 
@@ -1140,9 +1164,13 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
 		}
 	}
 
-	xfrm_pol_hold(ret);
+	if (read_seqcount_retry(&xfrm_policy_hash_generation, sequence))
+		goto retry;
+
+	if (ret && !xfrm_pol_hold_rcu(ret))
+		goto retry;
 fail:
-	read_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	rcu_read_unlock();
 
 	return ret;
 }
@@ -1219,10 +1247,9 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
 						 const struct flowi *fl)
 {
 	struct xfrm_policy *pol;
-	struct net *net = sock_net(sk);
 
 	rcu_read_lock();
-	read_lock_bh(&net->xfrm.xfrm_policy_lock);
+ again:
 	pol = rcu_dereference(sk->sk_policy[dir]);
 	if (pol != NULL) {
 		bool match = xfrm_selector_match(&pol->selector, fl,
@@ -1237,8 +1264,8 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
 			err = security_xfrm_policy_lookup(pol->security,
 						      fl->flowi_secid,
 						      policy_to_flow_dir(dir));
-			if (!err)
-				xfrm_pol_hold(pol);
+			if (!err && !xfrm_pol_hold_rcu(pol))
+				goto again;
 			else if (err == -ESRCH)
 				pol = NULL;
 			else
@@ -1247,7 +1274,6 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
 			pol = NULL;
 	}
 out:
-	read_unlock_bh(&net->xfrm.xfrm_policy_lock);
 	rcu_read_unlock();
 	return pol;
 }
@@ -1271,7 +1297,7 @@ static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
 
 	/* Socket policies are not hashed. */
 	if (!hlist_unhashed(&pol->bydst)) {
-		hlist_del(&pol->bydst);
+		hlist_del_rcu(&pol->bydst);
 		hlist_del(&pol->byidx);
 	}
 
@@ -1295,9 +1321,9 @@ int xfrm_policy_delete(struct xfrm_policy *pol, int dir)
 {
 	struct net *net = xp_net(pol);
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	pol = __xfrm_policy_unlink(pol, dir);
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 	if (pol) {
 		xfrm_policy_kill(pol);
 		return 0;
@@ -1316,7 +1342,7 @@ int xfrm_sk_policy_insert(struct sock *sk, int dir, struct xfrm_policy *pol)
 		return -EINVAL;
 #endif
 
-	write_lock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	old_pol = rcu_dereference_protected(sk->sk_policy[dir],
 				lockdep_is_held(&net->xfrm.xfrm_policy_lock));
 	if (pol) {
@@ -1334,7 +1360,7 @@ int xfrm_sk_policy_insert(struct sock *sk, int dir, struct xfrm_policy *pol)
 		 */
 		xfrm_sk_policy_unlink(old_pol, dir);
 	}
-	write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	if (old_pol) {
 		xfrm_policy_kill(old_pol);
@@ -1364,9 +1390,9 @@ static struct xfrm_policy *clone_policy(const struct xfrm_policy *old, int dir)
 		newp->type = old->type;
 		memcpy(newp->xfrm_vec, old->xfrm_vec,
 		       newp->xfrm_nr*sizeof(struct xfrm_tmpl));
-		write_lock_bh(&net->xfrm.xfrm_policy_lock);
+		spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 		xfrm_sk_policy_link(newp, dir);
-		write_unlock_bh(&net->xfrm.xfrm_policy_lock);
+		spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 		xfrm_pol_put(newp);
 	}
 	return newp;
@@ -3048,7 +3074,7 @@ static int __net_init xfrm_net_init(struct net *net)
 
 	/* Initialize the per-net locks here */
 	spin_lock_init(&net->xfrm.xfrm_state_lock);
-	rwlock_init(&net->xfrm.xfrm_policy_lock);
+	spin_lock_init(&net->xfrm.xfrm_policy_lock);
 	mutex_init(&net->xfrm.xfrm_cfg_mutex);
 
 	return 0;
@@ -3082,6 +3108,7 @@ static struct pernet_operations __net_initdata xfrm_net_ops = {
 void __init xfrm_init(void)
 {
 	register_pernet_subsys(&xfrm_net_ops);
+	seqcount_init(&xfrm_policy_hash_generation);
 	xfrm_input_init();
 }
 
@@ -3179,7 +3206,7 @@ static struct xfrm_policy *xfrm_migrate_policy_find(const struct xfrm_selector *
 	struct hlist_head *chain;
 	u32 priority = ~0U;
 
-	read_lock_bh(&net->xfrm.xfrm_policy_lock); /*FIXME*/
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	chain = policy_hash_direct(net, &sel->daddr, &sel->saddr, sel->family, dir);
 	hlist_for_each_entry(pol, chain, bydst) {
 		if (xfrm_migrate_selector_match(sel, &pol->selector) &&
@@ -3203,7 +3230,7 @@ static struct xfrm_policy *xfrm_migrate_policy_find(const struct xfrm_selector *
 
 	xfrm_pol_hold(ret);
 
-	read_unlock_bh(&net->xfrm.xfrm_policy_lock);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	return ret;
 }
diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
index 4fd725a0c500..cdc2e2e71bff 100644
--- a/net/xfrm/xfrm_replay.c
+++ b/net/xfrm/xfrm_replay.c
@@ -558,7 +558,7 @@ static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
 }
 
-static struct xfrm_replay xfrm_replay_legacy = {
+static const struct xfrm_replay xfrm_replay_legacy = {
 	.advance	= xfrm_replay_advance,
 	.check		= xfrm_replay_check,
 	.recheck	= xfrm_replay_check,
@@ -566,7 +566,7 @@ static struct xfrm_replay xfrm_replay_legacy = {
 	.overflow	= xfrm_replay_overflow,
 };
 
-static struct xfrm_replay xfrm_replay_bmp = {
+static const struct xfrm_replay xfrm_replay_bmp = {
 	.advance	= xfrm_replay_advance_bmp,
 	.check		= xfrm_replay_check_bmp,
 	.recheck	= xfrm_replay_check_bmp,
@@ -574,7 +574,7 @@ static struct xfrm_replay xfrm_replay_bmp = {
 	.overflow	= xfrm_replay_overflow_bmp,
 };
 
-static struct xfrm_replay xfrm_replay_esn = {
+static const struct xfrm_replay xfrm_replay_esn = {
 	.advance	= xfrm_replay_advance_esn,
 	.check		= xfrm_replay_check_esn,
 	.recheck	= xfrm_replay_recheck_esn,
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 9895a8c56d8c..ba8bf518ba14 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -28,6 +28,11 @@
 
 #include "xfrm_hash.h"
 
+#define xfrm_state_deref_prot(table, net) \
+	rcu_dereference_protected((table), lockdep_is_held(&(net)->xfrm.xfrm_state_lock))
+
+static void xfrm_state_gc_task(struct work_struct *work);
+
 /* Each xfrm_state may be linked to two tables:
 
    1. Hash table by (spi,daddr,ah/esp) to find SA by SPI. (input,ctl)
@@ -36,6 +41,15 @@
  */
 
 static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;
+static __read_mostly seqcount_t xfrm_state_hash_generation = SEQCNT_ZERO(xfrm_state_hash_generation);
+
+static DECLARE_WORK(xfrm_state_gc_work, xfrm_state_gc_task);
+static HLIST_HEAD(xfrm_state_gc_list);
+
+static inline bool xfrm_state_hold_rcu(struct xfrm_state __rcu *x)
+{
+	return atomic_inc_not_zero(&x->refcnt);
+}
 
 static inline unsigned int xfrm_dst_hash(struct net *net,
 					 const xfrm_address_t *daddr,
@@ -76,18 +90,18 @@ static void xfrm_hash_transfer(struct hlist_head *list,
 		h = __xfrm_dst_hash(&x->id.daddr, &x->props.saddr,
 				    x->props.reqid, x->props.family,
 				    nhashmask);
-		hlist_add_head(&x->bydst, ndsttable+h);
+		hlist_add_head_rcu(&x->bydst, ndsttable + h);
 
 		h = __xfrm_src_hash(&x->id.daddr, &x->props.saddr,
 				    x->props.family,
 				    nhashmask);
-		hlist_add_head(&x->bysrc, nsrctable+h);
+		hlist_add_head_rcu(&x->bysrc, nsrctable + h);
 
 		if (x->id.spi) {
 			h = __xfrm_spi_hash(&x->id.daddr, x->id.spi,
 					    x->id.proto, x->props.family,
 					    nhashmask);
-			hlist_add_head(&x->byspi, nspitable+h);
+			hlist_add_head_rcu(&x->byspi, nspitable + h);
 		}
 	}
 }
@@ -122,25 +136,29 @@ static void xfrm_hash_resize(struct work_struct *work)
 	}
 
 	spin_lock_bh(&net->xfrm.xfrm_state_lock);
+	write_seqcount_begin(&xfrm_state_hash_generation);
 
 	nhashmask = (nsize / sizeof(struct hlist_head)) - 1U;
+	odst = xfrm_state_deref_prot(net->xfrm.state_bydst, net);
 	for (i = net->xfrm.state_hmask; i >= 0; i--)
-		xfrm_hash_transfer(net->xfrm.state_bydst+i, ndst, nsrc, nspi,
-				   nhashmask);
+		xfrm_hash_transfer(odst + i, ndst, nsrc, nspi, nhashmask);
 
-	odst = net->xfrm.state_bydst;
-	osrc = net->xfrm.state_bysrc;
-	ospi = net->xfrm.state_byspi;
+	osrc = xfrm_state_deref_prot(net->xfrm.state_bysrc, net);
+	ospi = xfrm_state_deref_prot(net->xfrm.state_byspi, net);
 	ohashmask = net->xfrm.state_hmask;
 
-	net->xfrm.state_bydst = ndst;
-	net->xfrm.state_bysrc = nsrc;
-	net->xfrm.state_byspi = nspi;
+	rcu_assign_pointer(net->xfrm.state_bydst, ndst);
+	rcu_assign_pointer(net->xfrm.state_bysrc, nsrc);
+	rcu_assign_pointer(net->xfrm.state_byspi, nspi);
 	net->xfrm.state_hmask = nhashmask;
 
+	write_seqcount_end(&xfrm_state_hash_generation);
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 
 	osize = (ohashmask + 1) * sizeof(struct hlist_head);
+
+	synchronize_rcu();
+
 	xfrm_hash_free(odst, osize);
 	xfrm_hash_free(osrc, osize);
 	xfrm_hash_free(ospi, osize);
@@ -355,15 +373,16 @@ static void xfrm_state_gc_destroy(struct xfrm_state *x)
 
 static void xfrm_state_gc_task(struct work_struct *work)
 {
-	struct net *net = container_of(work, struct net, xfrm.state_gc_work);
 	struct xfrm_state *x;
 	struct hlist_node *tmp;
 	struct hlist_head gc_list;
 
 	spin_lock_bh(&xfrm_state_gc_lock);
-	hlist_move_list(&net->xfrm.state_gc_list, &gc_list);
+	hlist_move_list(&xfrm_state_gc_list, &gc_list);
 	spin_unlock_bh(&xfrm_state_gc_lock);
 
+	synchronize_rcu();
+
 	hlist_for_each_entry_safe(x, tmp, &gc_list, gclist)
 		xfrm_state_gc_destroy(x);
 }
@@ -500,14 +519,12 @@ EXPORT_SYMBOL(xfrm_state_alloc);
 
 void __xfrm_state_destroy(struct xfrm_state *x)
 {
-	struct net *net = xs_net(x);
-
 	WARN_ON(x->km.state != XFRM_STATE_DEAD);
 
 	spin_lock_bh(&xfrm_state_gc_lock);
-	hlist_add_head(&x->gclist, &net->xfrm.state_gc_list);
+	hlist_add_head(&x->gclist, &xfrm_state_gc_list);
 	spin_unlock_bh(&xfrm_state_gc_lock);
-	schedule_work(&net->xfrm.state_gc_work);
+	schedule_work(&xfrm_state_gc_work);
 }
 EXPORT_SYMBOL(__xfrm_state_destroy);
 
@@ -520,10 +537,10 @@ int __xfrm_state_delete(struct xfrm_state *x)
 		x->km.state = XFRM_STATE_DEAD;
 		spin_lock(&net->xfrm.xfrm_state_lock);
 		list_del(&x->km.all);
-		hlist_del(&x->bydst);
-		hlist_del(&x->bysrc);
+		hlist_del_rcu(&x->bydst);
+		hlist_del_rcu(&x->bysrc);
 		if (x->id.spi)
-			hlist_del(&x->byspi);
+			hlist_del_rcu(&x->byspi);
 		net->xfrm.state_num--;
 		spin_unlock(&net->xfrm.xfrm_state_lock);
 
@@ -659,7 +676,7 @@ static struct xfrm_state *__xfrm_state_lookup(struct net *net, u32 mark,
 	unsigned int h = xfrm_spi_hash(net, daddr, spi, proto, family);
 	struct xfrm_state *x;
 
-	hlist_for_each_entry(x, net->xfrm.state_byspi+h, byspi) {
+	hlist_for_each_entry_rcu(x, net->xfrm.state_byspi + h, byspi) {
 		if (x->props.family != family ||
 		    x->id.spi       != spi ||
 		    x->id.proto     != proto ||
@@ -668,7 +685,8 @@ static struct xfrm_state *__xfrm_state_lookup(struct net *net, u32 mark,
 
 		if ((mark & x->mark.m) != x->mark.v)
 			continue;
-		xfrm_state_hold(x);
+		if (!xfrm_state_hold_rcu(x))
+			continue;
 		return x;
 	}
 
@@ -683,7 +701,7 @@ static struct xfrm_state *__xfrm_state_lookup_byaddr(struct net *net, u32 mark,
 	unsigned int h = xfrm_src_hash(net, daddr, saddr, family);
 	struct xfrm_state *x;
 
-	hlist_for_each_entry(x, net->xfrm.state_bysrc+h, bysrc) {
+	hlist_for_each_entry_rcu(x, net->xfrm.state_bysrc + h, bysrc) {
 		if (x->props.family != family ||
 		    x->id.proto     != proto ||
 		    !xfrm_addr_equal(&x->id.daddr, daddr, family) ||
@@ -692,7 +710,8 @@ static struct xfrm_state *__xfrm_state_lookup_byaddr(struct net *net, u32 mark,
 
 		if ((mark & x->mark.m) != x->mark.v)
 			continue;
-		xfrm_state_hold(x);
+		if (!xfrm_state_hold_rcu(x))
+			continue;
 		return x;
 	}
 
@@ -775,13 +794,16 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 	struct xfrm_state *best = NULL;
 	u32 mark = pol->mark.v & pol->mark.m;
 	unsigned short encap_family = tmpl->encap_family;
+	unsigned int sequence;
 	struct km_event c;
 
 	to_put = NULL;
 
-	spin_lock_bh(&net->xfrm.xfrm_state_lock);
+	sequence = read_seqcount_begin(&xfrm_state_hash_generation);
+
+	rcu_read_lock();
 	h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family);
-	hlist_for_each_entry(x, net->xfrm.state_bydst+h, bydst) {
+	hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) {
 		if (x->props.family == encap_family &&
 		    x->props.reqid == tmpl->reqid &&
 		    (mark & x->mark.m) == x->mark.v &&
@@ -797,7 +819,7 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 		goto found;
 
 	h_wildcard = xfrm_dst_hash(net, daddr, &saddr_wildcard, tmpl->reqid, encap_family);
-	hlist_for_each_entry(x, net->xfrm.state_bydst+h_wildcard, bydst) {
+	hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h_wildcard, bydst) {
 		if (x->props.family == encap_family &&
 		    x->props.reqid == tmpl->reqid &&
 		    (mark & x->mark.m) == x->mark.v &&
@@ -850,19 +872,21 @@ found:
 		}
 
 		if (km_query(x, tmpl, pol) == 0) {
+			spin_lock_bh(&net->xfrm.xfrm_state_lock);
 			x->km.state = XFRM_STATE_ACQ;
 			list_add(&x->km.all, &net->xfrm.state_all);
-			hlist_add_head(&x->bydst, net->xfrm.state_bydst+h);
+			hlist_add_head_rcu(&x->bydst, net->xfrm.state_bydst + h);
 			h = xfrm_src_hash(net, daddr, saddr, encap_family);
-			hlist_add_head(&x->bysrc, net->xfrm.state_bysrc+h);
+			hlist_add_head_rcu(&x->bysrc, net->xfrm.state_bysrc + h);
 			if (x->id.spi) {
 				h = xfrm_spi_hash(net, &x->id.daddr, x->id.spi, x->id.proto, encap_family);
-				hlist_add_head(&x->byspi, net->xfrm.state_byspi+h);
+				hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h);
 			}
 			x->lft.hard_add_expires_seconds = net->xfrm.sysctl_acq_expires;
 			tasklet_hrtimer_start(&x->mtimer, ktime_set(net->xfrm.sysctl_acq_expires, 0), HRTIMER_MODE_REL);
 			net->xfrm.state_num++;
 			xfrm_hash_grow_check(net, x->bydst.next != NULL);
+			spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 		} else {
 			x->km.state = XFRM_STATE_DEAD;
 			to_put = x;
@@ -871,13 +895,26 @@ found:
 		}
 	}
 out:
-	if (x)
-		xfrm_state_hold(x);
-	else
+	if (x) {
+		if (!xfrm_state_hold_rcu(x)) {
+			*err = -EAGAIN;
+			x = NULL;
+		}
+	} else {
 		*err = acquire_in_progress ? -EAGAIN : error;
-	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
+	}
+	rcu_read_unlock();
 	if (to_put)
 		xfrm_state_put(to_put);
+
+	if (read_seqcount_retry(&xfrm_state_hash_generation, sequence)) {
+		*err = -EAGAIN;
+		if (x) {
+			xfrm_state_put(x);
+			x = NULL;
+		}
+	}
+
 	return x;
 }
 
@@ -945,16 +982,16 @@ static void __xfrm_state_insert(struct xfrm_state *x)
 
 	h = xfrm_dst_hash(net, &x->id.daddr, &x->props.saddr,
 			  x->props.reqid, x->props.family);
-	hlist_add_head(&x->bydst, net->xfrm.state_bydst+h);
+	hlist_add_head_rcu(&x->bydst, net->xfrm.state_bydst + h);
 
 	h = xfrm_src_hash(net, &x->id.daddr, &x->props.saddr, x->props.family);
-	hlist_add_head(&x->bysrc, net->xfrm.state_bysrc+h);
+	hlist_add_head_rcu(&x->bysrc, net->xfrm.state_bysrc + h);
 
 	if (x->id.spi) {
 		h = xfrm_spi_hash(net, &x->id.daddr, x->id.spi, x->id.proto,
 				  x->props.family);
 
-		hlist_add_head(&x->byspi, net->xfrm.state_byspi+h);
+		hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h);
 	}
 
 	tasklet_hrtimer_start(&x->mtimer, ktime_set(1, 0), HRTIMER_MODE_REL);
@@ -1063,9 +1100,9 @@ static struct xfrm_state *__find_acq_core(struct net *net,
 		xfrm_state_hold(x);
 		tasklet_hrtimer_start(&x->mtimer, ktime_set(net->xfrm.sysctl_acq_expires, 0), HRTIMER_MODE_REL);
 		list_add(&x->km.all, &net->xfrm.state_all);
-		hlist_add_head(&x->bydst, net->xfrm.state_bydst+h);
+		hlist_add_head_rcu(&x->bydst, net->xfrm.state_bydst + h);
 		h = xfrm_src_hash(net, daddr, saddr, family);
-		hlist_add_head(&x->bysrc, net->xfrm.state_bysrc+h);
+		hlist_add_head_rcu(&x->bysrc, net->xfrm.state_bysrc + h);
 
 		net->xfrm.state_num++;
 
@@ -1581,7 +1618,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high)
 	if (x->id.spi) {
 		spin_lock_bh(&net->xfrm.xfrm_state_lock);
 		h = xfrm_spi_hash(net, &x->id.daddr, x->id.spi, x->id.proto, x->props.family);
-		hlist_add_head(&x->byspi, net->xfrm.state_byspi+h);
+		hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h);
 		spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 
 		err = 0;
@@ -2099,8 +2136,6 @@ int __net_init xfrm_state_init(struct net *net)
 
 	net->xfrm.state_num = 0;
 	INIT_WORK(&net->xfrm.state_hash_work, xfrm_hash_resize);
-	INIT_HLIST_HEAD(&net->xfrm.state_gc_list);
-	INIT_WORK(&net->xfrm.state_gc_work, xfrm_state_gc_task);
 	spin_lock_init(&net->xfrm.xfrm_state_lock);
 	return 0;
 
@@ -2118,7 +2153,7 @@ void xfrm_state_fini(struct net *net)
 
 	flush_work(&net->xfrm.state_hash_work);
 	xfrm_state_flush(net, IPSEC_PROTO_ANY, false);
-	flush_work(&net->xfrm.state_gc_work);
+	flush_work(&xfrm_state_gc_work);
 
 	WARN_ON(!list_empty(&net->xfrm.state_all));