Revert "xfrm: destroy xfrm_state synchronously on net exit path"

[ Upstream commit 2a198bbec6913ae1c90ec963750003c6213668c7 ]

This reverts commit f75a2804da391571563c4b6b29e7797787332673.

With all states (whether user or kern) removed from the hashtables
during deletion, there's no need for synchronous destruction of
states. xfrm6_tunnel states still need to have been destroyed (which
will be the case when its last user is deleted (not destroyed)) so
that xfrm6_tunnel_free_spi removes it from the per-netns hashtable
before the netns is destroyed.

This has the benefit of skipping one synchronize_rcu per state (in
__xfrm_state_destroy(sync=true)) when we exit a netns.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>

Author: qsn

include/net/xfrm.h

@@ -850,7 +850,7 @@ static inline void xfrm_pols_put(struct xfrm_policy **pols, int npols)
 		xfrm_pol_put(pols[i]);
 }
 
-void __xfrm_state_destroy(struct xfrm_state *, bool);
+void __xfrm_state_destroy(struct xfrm_state *);
 
 static inline void __xfrm_state_put(struct xfrm_state *x)
 {
@@ -860,13 +860,7 @@ static inline void __xfrm_state_put(struct xfrm_state *x)
 static inline void xfrm_state_put(struct xfrm_state *x)
 {
 	if (refcount_dec_and_test(&x->refcnt))
-		__xfrm_state_destroy(x, false);
-}
-
-static inline void xfrm_state_put_sync(struct xfrm_state *x)
-{
-	if (refcount_dec_and_test(&x->refcnt))
-		__xfrm_state_destroy(x, true);
+		__xfrm_state_destroy(x);
 }
 
 static inline void xfrm_state_hold(struct xfrm_state *x)
@@ -1638,7 +1632,7 @@ struct xfrmk_spdinfo {
 
 struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq);
 int xfrm_state_delete(struct xfrm_state *x);
-int xfrm_state_flush(struct net *net, u8 proto, bool task_valid, bool sync);
+int xfrm_state_flush(struct net *net, u8 proto, bool task_valid);
 int xfrm_dev_state_flush(struct net *net, struct net_device *dev, bool task_valid);
 void xfrm_sad_getinfo(struct net *net, struct xfrmk_sadinfo *si);
 void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si);

net/ipv6/xfrm6_tunnel.c

@@ -344,7 +344,7 @@ static void __net_exit xfrm6_tunnel_net_exit(struct net *net)
 	struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
 	unsigned int i;
 
-	xfrm_state_flush(net, 0, false, true);
+	xfrm_state_flush(net, IPSEC_PROTO_ANY, false);
 	xfrm_flush_gc();
 
 	for (i = 0; i < XFRM6_TUNNEL_SPI_BYADDR_HSIZE; i++)

net/key/af_key.c

@@ -1776,7 +1776,7 @@ static int pfkey_flush(struct sock *sk, struct sk_buff *skb, const struct sadb_m
 	if (proto == 0)
 		return -EINVAL;
 
-	err = xfrm_state_flush(net, proto, true, false);
+	err = xfrm_state_flush(net, proto, true);
 	err2 = unicast_flush_resp(sk, hdr);
 	if (err || err2) {
 		if (err == -ESRCH) /* empty table - go quietly */

net/xfrm/xfrm_state.c

@@ -431,7 +431,7 @@ void xfrm_state_free(struct xfrm_state *x)
 }
 EXPORT_SYMBOL(xfrm_state_free);
 
-static void ___xfrm_state_destroy(struct xfrm_state *x)
+static void xfrm_state_gc_destroy(struct xfrm_state *x)
 {
 	tasklet_hrtimer_cancel(&x->mtimer);
 	del_timer_sync(&x->rtimer);
@@ -475,7 +475,7 @@ static void xfrm_state_gc_task(struct work_struct *work)
 	synchronize_rcu();
 
 	hlist_for_each_entry_safe(x, tmp, &gc_list, gclist)
-		___xfrm_state_destroy(x);
+		xfrm_state_gc_destroy(x);
 }
 
 static enum hrtimer_restart xfrm_timer_handler(struct hrtimer *me)
@@ -599,19 +599,14 @@ struct xfrm_state *xfrm_state_alloc(struct net *net)
 }
 EXPORT_SYMBOL(xfrm_state_alloc);
 
-void __xfrm_state_destroy(struct xfrm_state *x, bool sync)
+void __xfrm_state_destroy(struct xfrm_state *x)
 {
 	WARN_ON(x->km.state != XFRM_STATE_DEAD);
 
-	if (sync) {
-		synchronize_rcu();
-		___xfrm_state_destroy(x);
-	} else {
-		spin_lock_bh(&xfrm_state_gc_lock);
-		hlist_add_head(&x->gclist, &xfrm_state_gc_list);
-		spin_unlock_bh(&xfrm_state_gc_lock);
-		schedule_work(&xfrm_state_gc_work);
-	}
+	spin_lock_bh(&xfrm_state_gc_lock);
+	hlist_add_head(&x->gclist, &xfrm_state_gc_list);
+	spin_unlock_bh(&xfrm_state_gc_lock);
+	schedule_work(&xfrm_state_gc_work);
 }
 EXPORT_SYMBOL(__xfrm_state_destroy);
 
@@ -717,7 +712,7 @@ xfrm_dev_state_flush_secctx_check(struct net *net, struct net_device *dev, bool
 }
 #endif
 
-int xfrm_state_flush(struct net *net, u8 proto, bool task_valid, bool sync)
+int xfrm_state_flush(struct net *net, u8 proto, bool task_valid)
 {
 	int i, err = 0, cnt = 0;
 
@@ -2425,7 +2420,7 @@ void xfrm_state_fini(struct net *net)
 	unsigned int sz;
 
 	flush_work(&net->xfrm.state_hash_work);
-	xfrm_state_flush(net, 0, false, true);
+	xfrm_state_flush(net, IPSEC_PROTO_ANY, false);
 	flush_work(&xfrm_state_gc_work);
 
 	WARN_ON(!list_empty(&net->xfrm.state_all));

net/xfrm/xfrm_user.c

@@ -1958,7 +1958,7 @@ static int xfrm_flush_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct xfrm_usersa_flush *p = nlmsg_data(nlh);
 	int err;
 
-	err = xfrm_state_flush(net, p->proto, true, false);
+	err = xfrm_state_flush(net, p->proto, true);
 	if (err) {
 		if (err == -ESRCH) /* empty table */
 			return 0;