[PATCH ipsec-next 0/6] xfrm: policy: make policy backend const

[PATCH ipsec-next 0/6] xfrm: policy: make policy backend const

[Florian Westphal]

Hi Steffen,

This series removes all places that need to write to the afinfo policy
backends.  This then allows us to make the structures const.

[PATCH ipsec-next 1/6] xfrm: policy: xfrm_get_tos cannot fail

[Florian Westphal]

The comment makes it look like get_tos() is used to validate something,
but it turns out the comment was about xfrm_find_bundle() which got removed
years ago.

xfrm_get_tos will return either the tos (ipv4) or 0 (ipv6).

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/xfrm/xfrm_policy.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 99ad1af2927f..6fffa2fac607 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1538,19 +1538,13 @@ xfrm_tmpl_resolve(struct xfrm_policy **pols, int npols, const struct flowi *fl,
 
 }
 
-/* Check that the bundle accepts the flow and its components are
- * still valid.
- */
-
-static inline int xfrm_get_tos(const struct flowi *fl, int family)
+static int xfrm_get_tos(const struct flowi *fl, int family)
 {
-	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
-	int tos;
-
-	if (!afinfo)
-		return -EINVAL;
+	struct xfrm_policy_afinfo *afinfo;
+	int tos = 0;
 
-	tos = afinfo->get_tos(fl);
+	afinfo = xfrm_policy_get_afinfo(family);
+	tos = afinfo ? afinfo->get_tos(fl) : 0;
 
 	xfrm_policy_put_afinfo(afinfo);
 
@@ -1705,9 +1699,6 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
 	xfrm_flowi_addr_get(fl, &saddr, &daddr, family);
 
 	tos = xfrm_get_tos(fl, family);
-	err = tos;
-	if (tos < 0)
-		goto put_states;
 
 	dst_hold(dst);
 
-- 
2.10.2

[PATCH ipsec-next 2/6] xfrm: policy: xfrm_policy_unregister_afinfo can return void

[Florian Westphal]

Nothing checks the return value. Also, the errors returned on unregister
are impossible (we only support INET and INET6, so no way
xfrm_policy_afinfo[afinfo->family] can be anything other than 'afinfo'
itself).

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/xfrm.h     |  2 +-
 net/xfrm/xfrm_policy.c | 35 +++++++++++++----------------------
 2 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index da0e4dd653e2..39037b1cce7a 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -304,7 +304,7 @@ struct xfrm_policy_afinfo {
 };
 
 int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo);
-int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo);
+void xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo);
 void km_policy_notify(struct xfrm_policy *xp, int dir,
 		      const struct km_event *c);
 void km_state_notify(struct xfrm_state *x, const struct km_event *c);
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 6fffa2fac607..794148f76ae2 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2883,34 +2883,25 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 }
 EXPORT_SYMBOL(xfrm_policy_register_afinfo);
 
-int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
+void xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
 {
-	int err = 0;
-	if (unlikely(afinfo == NULL))
-		return -EINVAL;
+	struct dst_ops *dst_ops = afinfo->dst_ops;
+
 	if (unlikely(afinfo->family >= NPROTO))
-		return -EAFNOSUPPORT;
-	spin_lock(&xfrm_policy_afinfo_lock);
-	if (likely(xfrm_policy_afinfo[afinfo->family] != NULL)) {
-		if (unlikely(xfrm_policy_afinfo[afinfo->family] != afinfo))
-			err = -EINVAL;
-		else
-			RCU_INIT_POINTER(xfrm_policy_afinfo[afinfo->family],
+		return;
+
+	if (likely(xfrm_policy_afinfo[afinfo->family] != afinfo)) {
+		RCU_INIT_POINTER(xfrm_policy_afinfo[afinfo->family],
 					 NULL);
 	}
-	spin_unlock(&xfrm_policy_afinfo_lock);
-	if (!err) {
-		struct dst_ops *dst_ops = afinfo->dst_ops;
 
-		synchronize_rcu();
+	synchronize_rcu();
 
-		dst_ops->kmem_cachep = NULL;
-		dst_ops->check = NULL;
-		dst_ops->negative_advice = NULL;
-		dst_ops->link_failure = NULL;
-		afinfo->garbage_collect = NULL;
-	}
-	return err;
+	dst_ops->kmem_cachep = NULL;
+	dst_ops->check = NULL;
+	dst_ops->negative_advice = NULL;
+	dst_ops->link_failure = NULL;
+	afinfo->garbage_collect = NULL;
 }
 EXPORT_SYMBOL(xfrm_policy_unregister_afinfo);
 
-- 
2.10.2

[PATCH ipsec-next 3/6] xfrm: policy: remove garbage_collect callback

[Florian Westphal]

Just call xfrm_garbage_collect_deferred() directly.
This gets rid of a write to afinfo in register/unregister and allows to
constify afinfo later on.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/xfrm.h      | 2 +-
 net/ipv4/xfrm4_policy.c | 2 +-
 net/ipv6/xfrm6_policy.c | 2 +-
 net/xfrm/xfrm_policy.c  | 6 ++----
 4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 39037b1cce7a..a22368edd105 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -282,7 +282,6 @@ struct xfrm_dst;
 struct xfrm_policy_afinfo {
 	unsigned short		family;
 	struct dst_ops		*dst_ops;
-	void			(*garbage_collect)(struct net *net);
 	struct dst_entry	*(*dst_lookup)(struct net *net,
 					       int tos, int oif,
 					       const xfrm_address_t *saddr,
@@ -1169,6 +1168,7 @@ static inline void xfrm_sk_free_policy(struct sock *sk)
 }
 
 void xfrm_garbage_collect(struct net *net);
+void xfrm_garbage_collect_deferred(struct net *net);
 
 #else
 
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 6a7ff6957535..77ca91d7b79c 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -219,7 +219,7 @@ static inline int xfrm4_garbage_collect(struct dst_ops *ops)
 {
 	struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops);
 
-	xfrm4_policy_afinfo.garbage_collect(net);
+	xfrm_garbage_collect_deferred(net);
 	return (dst_entries_get_slow(ops) > ops->gc_thresh * 2);
 }
 
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index e0f71c01d728..c273f22b12af 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -220,7 +220,7 @@ static inline int xfrm6_garbage_collect(struct dst_ops *ops)
 {
 	struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);
 
-	xfrm6_policy_afinfo.garbage_collect(net);
+	xfrm_garbage_collect_deferred(net);
 	return dst_entries_get_fast(ops) > ops->gc_thresh * 2;
 }
 
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 794148f76ae2..80695a157b6e 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2733,10 +2733,11 @@ void xfrm_garbage_collect(struct net *net)
 }
 EXPORT_SYMBOL(xfrm_garbage_collect);
 
-static void xfrm_garbage_collect_deferred(struct net *net)
+void xfrm_garbage_collect_deferred(struct net *net)
 {
 	flow_cache_flush_deferred(net);
 }
+EXPORT_SYMBOL(xfrm_garbage_collect_deferred);
 
 static void xfrm_init_pmtu(struct dst_entry *dst)
 {
@@ -2873,8 +2874,6 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 			dst_ops->link_failure = xfrm_link_failure;
 		if (likely(dst_ops->neigh_lookup == NULL))
 			dst_ops->neigh_lookup = xfrm_neigh_lookup;
-		if (likely(afinfo->garbage_collect == NULL))
-			afinfo->garbage_collect = xfrm_garbage_collect_deferred;
 		rcu_assign_pointer(xfrm_policy_afinfo[afinfo->family], afinfo);
 	}
 	spin_unlock(&xfrm_policy_afinfo_lock);
@@ -2901,7 +2900,6 @@ void xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
 	dst_ops->check = NULL;
 	dst_ops->negative_advice = NULL;
 	dst_ops->link_failure = NULL;
-	afinfo->garbage_collect = NULL;
 }
 EXPORT_SYMBOL(xfrm_policy_unregister_afinfo);
 
-- 
2.10.2

[PATCH ipsec-next 4/6] xfrm: policy: remove family field

[Florian Westphal]

Only needed it to register the policy backend at init time.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/xfrm.h      |  5 ++---
 net/ipv4/xfrm4_policy.c |  5 +----
 net/ipv6/xfrm6_policy.c |  5 +----
 net/xfrm/xfrm_policy.c  | 34 +++++++++++++++++-----------------
 4 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index a22368edd105..6e061309adca 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -280,7 +280,6 @@ struct net_device;
 struct xfrm_type;
 struct xfrm_dst;
 struct xfrm_policy_afinfo {
-	unsigned short		family;
 	struct dst_ops		*dst_ops;
 	struct dst_entry	*(*dst_lookup)(struct net *net,
 					       int tos, int oif,
@@ -302,8 +301,8 @@ struct xfrm_policy_afinfo {
 	struct dst_entry	*(*blackhole_route)(struct net *net, struct dst_entry *orig);
 };
 
-int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo);
-void xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo);
+int xfrm_policy_register_afinfo(const struct xfrm_policy_afinfo *afinfo, int family);
+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 km_state_notify(struct xfrm_state *x, const struct km_event *c);
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 77ca91d7b79c..25613539766f 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -17,8 +17,6 @@
 #include <net/ip.h>
 #include <net/l3mdev.h>
 
-static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
-
 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
 					    int tos, int oif,
 					    const xfrm_address_t *saddr,
@@ -272,7 +270,6 @@ static struct dst_ops xfrm4_dst_ops_template = {
 };
 
 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
-	.family = 		AF_INET,
 	.dst_ops =		&xfrm4_dst_ops_template,
 	.dst_lookup =		xfrm4_dst_lookup,
 	.get_saddr =		xfrm4_get_saddr,
@@ -376,7 +373,7 @@ static struct pernet_operations __net_initdata xfrm4_net_ops = {
 
 static void __init xfrm4_policy_init(void)
 {
-	xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
+	xfrm_policy_register_afinfo(&xfrm4_policy_afinfo, AF_INET);
 }
 
 void __init xfrm4_init(void)
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index c273f22b12af..3217e85334e3 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -25,8 +25,6 @@
 #include <net/mip6.h>
 #endif
 
-static struct xfrm_policy_afinfo xfrm6_policy_afinfo;
-
 static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos, int oif,
 					  const xfrm_address_t *saddr,
 					  const xfrm_address_t *daddr)
@@ -292,7 +290,6 @@ static struct dst_ops xfrm6_dst_ops_template = {
 };
 
 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
-	.family =		AF_INET6,
 	.dst_ops =		&xfrm6_dst_ops_template,
 	.dst_lookup =		xfrm6_dst_lookup,
 	.get_saddr =		xfrm6_get_saddr,
@@ -305,7 +302,7 @@ static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 
 static int __init xfrm6_policy_init(void)
 {
-	return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
+	return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 }
 
 static void xfrm6_policy_fini(void)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 80695a157b6e..7698785876d7 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -45,7 +45,7 @@ struct xfrm_flo {
 };
 
 static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
-static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO]
+static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
 						__read_mostly;
 
 static struct kmem_cache *xfrm_dst_cache __read_mostly;
@@ -103,11 +103,11 @@ bool xfrm_selector_match(const struct xfrm_selector *sel, const struct flowi *fl
 	return false;
 }
 
-static struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family)
+static const struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family)
 {
-	struct xfrm_policy_afinfo *afinfo;
+	const struct xfrm_policy_afinfo *afinfo;
 
-	if (unlikely(family >= NPROTO))
+	if (unlikely(family >= ARRAY_SIZE(xfrm_policy_afinfo)))
 		return NULL;
 	rcu_read_lock();
 	afinfo = rcu_dereference(xfrm_policy_afinfo[family]);
@@ -2848,15 +2848,15 @@ static struct neighbour *xfrm_neigh_lookup(const struct dst_entry *dst,
 	return dst->path->ops->neigh_lookup(dst, skb, daddr);
 }
 
-int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
+int xfrm_policy_register_afinfo(const struct xfrm_policy_afinfo *afinfo, int family)
 {
 	int err = 0;
-	if (unlikely(afinfo == NULL))
-		return -EINVAL;
-	if (unlikely(afinfo->family >= NPROTO))
+
+	if (WARN_ON(family >= ARRAY_SIZE(xfrm_policy_afinfo)))
 		return -EAFNOSUPPORT;
+
 	spin_lock(&xfrm_policy_afinfo_lock);
-	if (unlikely(xfrm_policy_afinfo[afinfo->family] != NULL))
+	if (unlikely(xfrm_policy_afinfo[family] != NULL))
 		err = -EEXIST;
 	else {
 		struct dst_ops *dst_ops = afinfo->dst_ops;
@@ -2874,7 +2874,7 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 			dst_ops->link_failure = xfrm_link_failure;
 		if (likely(dst_ops->neigh_lookup == NULL))
 			dst_ops->neigh_lookup = xfrm_neigh_lookup;
-		rcu_assign_pointer(xfrm_policy_afinfo[afinfo->family], afinfo);
+		rcu_assign_pointer(xfrm_policy_afinfo[family], afinfo);
 	}
 	spin_unlock(&xfrm_policy_afinfo_lock);
 
@@ -2882,16 +2882,16 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 }
 EXPORT_SYMBOL(xfrm_policy_register_afinfo);
 
-void xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
+void xfrm_policy_unregister_afinfo(const struct xfrm_policy_afinfo *afinfo)
 {
 	struct dst_ops *dst_ops = afinfo->dst_ops;
+	int i;
 
-	if (unlikely(afinfo->family >= NPROTO))
-		return;
-
-	if (likely(xfrm_policy_afinfo[afinfo->family] != afinfo)) {
-		RCU_INIT_POINTER(xfrm_policy_afinfo[afinfo->family],
-					 NULL);
+	for (i = 0; i < ARRAY_SIZE(xfrm_policy_afinfo); i++) {
+		if (xfrm_policy_afinfo[i] != afinfo)
+			continue;
+		RCU_INIT_POINTER(xfrm_policy_afinfo[i], NULL);
+		break;
 	}
 
 	synchronize_rcu();
-- 
2.10.2

[PATCH ipsec-next 5/6] xfrm: policy: remove xfrm_policy_put_afinfo

[Florian Westphal]

Alternative is to keep it an make the (unused) afinfo arg const to avoid
the compiler warnings once the afinfo structs get constified.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/xfrm/xfrm_policy.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 7698785876d7..80ef0dcf0e29 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -116,11 +116,6 @@ static const struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short fa
 	return afinfo;
 }
 
-static void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo)
-{
-	rcu_read_unlock();
-}
-
 static inline struct dst_entry *__xfrm_dst_lookup(struct net *net,
 						  int tos, int oif,
 						  const xfrm_address_t *saddr,
@@ -136,7 +131,7 @@ static inline struct dst_entry *__xfrm_dst_lookup(struct net *net,
 
 	dst = afinfo->dst_lookup(net, tos, oif, saddr, daddr);
 
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return dst;
 }
@@ -1436,7 +1431,7 @@ xfrm_get_saddr(struct net *net, int oif, xfrm_address_t *local,
 	if (unlikely(afinfo == NULL))
 		return -EINVAL;
 	err = afinfo->get_saddr(net, oif, local, remote);
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 	return err;
 }
 
@@ -1546,7 +1541,7 @@ static int xfrm_get_tos(const struct flowi *fl, int family)
 	afinfo = xfrm_policy_get_afinfo(family);
 	tos = afinfo ? afinfo->get_tos(fl) : 0;
 
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return tos;
 }
@@ -1632,7 +1627,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 	} else
 		xdst = ERR_PTR(-ENOBUFS);
 
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return xdst;
 }
@@ -1649,7 +1644,7 @@ static inline int xfrm_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 
 	err = afinfo->init_path(path, dst, nfheader_len);
 
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return err;
 }
@@ -1666,7 +1661,7 @@ static inline int xfrm_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 
 	err = afinfo->fill_dst(xdst, dev, fl);
 
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return err;
 }
@@ -2215,7 +2210,7 @@ static struct dst_entry *make_blackhole(struct net *net, u16 family,
 	} else {
 		ret = afinfo->blackhole_route(net, dst_orig);
 	}
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 
 	return ret;
 }
@@ -2465,7 +2460,7 @@ int __xfrm_decode_session(struct sk_buff *skb, struct flowi *fl,
 
 	afinfo->decode_session(skb, fl, reverse);
 	err = security_xfrm_decode_session(skb, &fl->flowi_secid);
-	xfrm_policy_put_afinfo(afinfo);
+	rcu_read_unlock();
 	return err;
 }
 EXPORT_SYMBOL(__xfrm_decode_session);
-- 
2.10.2

[PATCH ipsec-next 6/6] xfrm: policy: make policy backend const

[Florian Westphal]

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/ipv4/xfrm4_policy.c |  2 +-
 net/ipv6/xfrm6_policy.c |  2 +-
 net/xfrm/xfrm_policy.c  | 18 +++++++++---------
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 25613539766f..71b4ecc195c7 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -269,7 +269,7 @@ static struct dst_ops xfrm4_dst_ops_template = {
 	.gc_thresh =		INT_MAX,
 };
 
-static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
+static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 	.dst_ops =		&xfrm4_dst_ops_template,
 	.dst_lookup =		xfrm4_dst_lookup,
 	.get_saddr =		xfrm4_get_saddr,
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 3217e85334e3..79651bc71bf0 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -289,7 +289,7 @@ static struct dst_ops xfrm6_dst_ops_template = {
 	.gc_thresh =		INT_MAX,
 };
 
-static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
+static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 	.dst_ops =		&xfrm6_dst_ops_template,
 	.dst_lookup =		xfrm6_dst_lookup,
 	.get_saddr =		xfrm6_get_saddr,
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 80ef0dcf0e29..04ed1a1ae019 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -45,7 +45,7 @@ struct xfrm_flo {
 };
 
 static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
-static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
+static struct xfrm_policy_afinfo const __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
 						__read_mostly;
 
 static struct kmem_cache *xfrm_dst_cache __read_mostly;
@@ -122,7 +122,7 @@ static inline struct dst_entry *__xfrm_dst_lookup(struct net *net,
 						  const xfrm_address_t *daddr,
 						  int family)
 {
-	struct xfrm_policy_afinfo *afinfo;
+	const struct xfrm_policy_afinfo *afinfo;
 	struct dst_entry *dst;
 
 	afinfo = xfrm_policy_get_afinfo(family);
@@ -1426,7 +1426,7 @@ xfrm_get_saddr(struct net *net, int oif, xfrm_address_t *local,
 	       xfrm_address_t *remote, unsigned short family)
 {
 	int err;
-	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
+	const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 
 	if (unlikely(afinfo == NULL))
 		return -EINVAL;
@@ -1535,7 +1535,7 @@ xfrm_tmpl_resolve(struct xfrm_policy **pols, int npols, const struct flowi *fl,
 
 static int xfrm_get_tos(const struct flowi *fl, int family)
 {
-	struct xfrm_policy_afinfo *afinfo;
+	const struct xfrm_policy_afinfo *afinfo;
 	int tos = 0;
 
 	afinfo = xfrm_policy_get_afinfo(family);
@@ -1598,7 +1598,7 @@ static const struct flow_cache_ops xfrm_bundle_fc_ops = {
 
 static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 {
-	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
+	const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 	struct dst_ops *dst_ops;
 	struct xfrm_dst *xdst;
 
@@ -1635,7 +1635,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 static inline int xfrm_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 				 int nfheader_len)
 {
-	struct xfrm_policy_afinfo *afinfo =
+	const struct xfrm_policy_afinfo *afinfo =
 		xfrm_policy_get_afinfo(dst->ops->family);
 	int err;
 
@@ -1652,7 +1652,7 @@ static inline int xfrm_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 static inline int xfrm_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 				const struct flowi *fl)
 {
-	struct xfrm_policy_afinfo *afinfo =
+	const struct xfrm_policy_afinfo *afinfo =
 		xfrm_policy_get_afinfo(xdst->u.dst.ops->family);
 	int err;
 
@@ -2201,7 +2201,7 @@ xfrm_bundle_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir,
 static struct dst_entry *make_blackhole(struct net *net, u16 family,
 					struct dst_entry *dst_orig)
 {
-	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
+	const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 	struct dst_entry *ret;
 
 	if (!afinfo) {
@@ -2452,7 +2452,7 @@ xfrm_policy_ok(const struct xfrm_tmpl *tmpl, const struct sec_path *sp, int star
 int __xfrm_decode_session(struct sk_buff *skb, struct flowi *fl,
 			  unsigned int family, int reverse)
 {
-	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
+	const struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 	int err;
 
 	if (unlikely(afinfo == NULL))
-- 
2.10.2

Re: [PATCH ipsec-next 0/6] xfrm: policy: make policy backend const

[Steffen Klassert]

On Tue, Feb 07, 2017 at 03:00:13PM +0100, Florian Westphal wrote:
> Hi Steffen,
> 
> This series removes all places that need to write to the afinfo policy
> backends.  This then allows us to make the structures const.

All applied to ipsec-next, thanks a lot Florian!