net: Allow fib_rule_unregister to batch

Refactor the code so fib_rules_register always takes a template instead
of the actual fib_rules_ops structure that will be used.  This is
required for network namespace support so 2 out of the 3 callers already
do this, it allows the error handling to be made common, and it allows
fib_rules_unregister to free the template for hte caller.

Modify fib_rules_unregister to use call_rcu instead of syncrhonize_rcu
to allw multiple namespaces to be cleaned up in the same rcu grace
period.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 57 insertions, 38 deletions

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index d4e875a58f8b..c07ac9650ebc 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -66,6 +66,7 @@ struct fib_rules_ops {
         struct list_head        rules_list;
         struct module           *owner;
         struct net              *fro_net;
+        struct rcu_head         rcu;
 };
 
 #define FRA_GENERIC_POLICY \
@@ -102,7 +103,7 @@ static inline u32 frh_get_table(struct fib_rule_hdr *frh, struct nlattr **nla)
         return frh->table;
 }
 
-extern int fib_rules_register(struct fib_rules_ops *);
+extern struct fib_rules_ops *fib_rules_register(struct fib_rules_ops *, struct net *);
 extern void fib_rules_unregister(struct fib_rules_ops *);
 extern void                     fib_rules_cleanup_ops(struct fib_rules_ops *);
 
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index ef0e7d9e664b..02a3b2c69c1e 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -72,7 +72,7 @@ static void flush_route_cache(struct fib_rules_ops *ops)
                 ops->flush_cache(ops);
 }
 
-int fib_rules_register(struct fib_rules_ops *ops)
+static int __fib_rules_register(struct fib_rules_ops *ops)
 {
         int err = -EEXIST;
         struct fib_rules_ops *o;
@@ -102,6 +102,28 @@ errout:
         return err;
 }
 
+struct fib_rules_ops *
+fib_rules_register(struct fib_rules_ops *tmpl, struct net *net)
+{
+        struct fib_rules_ops *ops;
+        int err;
+
+        ops = kmemdup(tmpl, sizeof (*ops), GFP_KERNEL);
+        if (ops == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        INIT_LIST_HEAD(&ops->rules_list);
+        ops->fro_net = net;
+
+        err = __fib_rules_register(ops);
+        if (err) {
+                kfree(ops);
+                ops = ERR_PTR(err);
+        }
+
+        return ops;
+}
+
 EXPORT_SYMBOL_GPL(fib_rules_register);
 
 void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
@@ -115,6 +137,15 @@ void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
 }
 EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);
 
+static void fib_rules_put_rcu(struct rcu_head *head)
+{
+        struct fib_rules_ops *ops = container_of(head, struct fib_rules_ops, rcu);
+        struct net *net = ops->fro_net;
+
+        release_net(net);
+        kfree(ops);
+}
+
 void fib_rules_unregister(struct fib_rules_ops *ops)
 {
         struct net *net = ops->fro_net;
@@ -124,8 +155,7 @@ void fib_rules_unregister(struct fib_rules_ops *ops)
         fib_rules_cleanup_ops(ops);
         spin_unlock(&net->rules_mod_lock);
 
-        synchronize_rcu();
-        release_net(net);
+        call_rcu(&ops->rcu, fib_rules_put_rcu);
 }
 
 EXPORT_SYMBOL_GPL(fib_rules_unregister);
diff --git a/net/decnet/dn_rules.c b/net/decnet/dn_rules.c
index 72495f25269f..7466c546f286 100644
--- a/net/decnet/dn_rules.c
+++ b/net/decnet/dn_rules.c
@@ -33,7 +33,7 @@
 #include <net/dn_dev.h>
 #include <net/dn_route.h>
 
-static struct fib_rules_ops dn_fib_rules_ops;
+static struct fib_rules_ops *dn_fib_rules_ops;
 
 struct dn_fib_rule
 {
@@ -56,7 +56,7 @@ int dn_fib_lookup(struct flowi *flp, struct dn_fib_res *res)
         };
         int err;
 
-        err = fib_rules_lookup(&dn_fib_rules_ops, flp, 0, &arg);
+        err = fib_rules_lookup(dn_fib_rules_ops, flp, 0, &arg);
         res->r = arg.rule;
 
         return err;
@@ -217,9 +217,9 @@ static u32 dn_fib_rule_default_pref(struct fib_rules_ops *ops)
         struct list_head *pos;
         struct fib_rule *rule;
 
-        if (!list_empty(&dn_fib_rules_ops.rules_list)) {
-                pos = dn_fib_rules_ops.rules_list.next;
-                if (pos->next != &dn_fib_rules_ops.rules_list) {
+        if (!list_empty(&dn_fib_rules_ops->rules_list)) {
+                pos = dn_fib_rules_ops->rules_list.next;
+                if (pos->next != &dn_fib_rules_ops->rules_list) {
                         rule = list_entry(pos->next, struct fib_rule, list);
                         if (rule->pref)
                                 return rule->pref - 1;
@@ -234,7 +234,7 @@ static void dn_fib_rule_flush_cache(struct fib_rules_ops *ops)
         dn_rt_cache_flush(-1);
 }
 
-static struct fib_rules_ops dn_fib_rules_ops = {
+static struct fib_rules_ops dn_fib_rules_ops_template = {
         .family         = AF_DECnet,
         .rule_size      = sizeof(struct dn_fib_rule),
         .addr_size      = sizeof(u16),
@@ -247,21 +247,23 @@ static struct fib_rules_ops dn_fib_rules_ops = {
         .flush_cache    = dn_fib_rule_flush_cache,
         .nlgroup        = RTNLGRP_DECnet_RULE,
         .policy         = dn_fib_rule_policy,
-        .rules_list     = LIST_HEAD_INIT(dn_fib_rules_ops.rules_list),
         .owner          = THIS_MODULE,
         .fro_net        = &init_net,
 };
 
 void __init dn_fib_rules_init(void)
 {
-        BUG_ON(fib_default_rule_add(&dn_fib_rules_ops, 0x7fff,
+        dn_fib_rules_ops =
+                fib_rules_register(&dn_fib_rules_ops_template, &init_net);
+        BUG_ON(IS_ERR(dn_fib_rules_ops));
+        BUG_ON(fib_default_rule_add(dn_fib_rules_ops, 0x7fff,
                                     RT_TABLE_MAIN, 0));
-        fib_rules_register(&dn_fib_rules_ops);
 }
 
 void __exit dn_fib_rules_cleanup(void)
 {
-        fib_rules_unregister(&dn_fib_rules_ops);
+        fib_rules_unregister(dn_fib_rules_ops);
+        rcu_barrier();
 }
 
 
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 1239ed23cab6..ca2d07b1c706 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -301,13 +301,9 @@ int __net_init fib4_rules_init(struct net *net)
         int err;
         struct fib_rules_ops *ops;
 
-        ops = kmemdup(&fib4_rules_ops_template, sizeof(*ops), GFP_KERNEL);
-        if (ops == NULL)
-                return -ENOMEM;
-        INIT_LIST_HEAD(&ops->rules_list);
-        ops->fro_net = net;
-
-        fib_rules_register(ops);
+        ops = fib_rules_register(&fib4_rules_ops_template, net);
+        if (IS_ERR(ops))
+                return PTR_ERR(ops);
 
         err = fib_default_rules_init(ops);
         if (err < 0)
@@ -318,12 +314,10 @@ int __net_init fib4_rules_init(struct net *net)
 fail:
         /* also cleans all rules already added */
         fib_rules_unregister(ops);
-        kfree(ops);
         return err;
 }
 
 void __net_exit fib4_rules_exit(struct net *net)
 {
         fib_rules_unregister(net->ipv4.rules_ops);
-        kfree(net->ipv4.rules_ops);
 }
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 3b38f49f2c28..b7aa7c64cc4a 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -264,16 +264,14 @@ static struct fib_rules_ops fib6_rules_ops_template = {
 
 static int fib6_rules_net_init(struct net *net)
 {
+        struct fib_rules_ops *ops;
         int err = -ENOMEM;
 
-        net->ipv6.fib6_rules_ops = kmemdup(&fib6_rules_ops_template,
-                                           sizeof(*net->ipv6.fib6_rules_ops),
-                                           GFP_KERNEL);
-        if (!net->ipv6.fib6_rules_ops)
-                goto out;
+        ops = fib_rules_register(&fib6_rules_ops_template, net);
+        if (IS_ERR(ops))
+                return PTR_ERR(ops);
+        net->ipv6.fib6_rules_ops = ops;
 
-        net->ipv6.fib6_rules_ops->fro_net = net;
-        INIT_LIST_HEAD(&net->ipv6.fib6_rules_ops->rules_list);
 
         err = fib_default_rule_add(net->ipv6.fib6_rules_ops, 0,
                                    RT6_TABLE_LOCAL, 0);
@@ -283,25 +281,19 @@ static int fib6_rules_net_init(struct net *net)
         err = fib_default_rule_add(net->ipv6.fib6_rules_ops,
                                    0x7FFE, RT6_TABLE_MAIN, 0);
         if (err)
-                goto out_fib6_default_rule_add;
+                goto out_fib6_rules_ops;
 
-        err = fib_rules_register(net->ipv6.fib6_rules_ops);
-        if (err)
-                goto out_fib6_default_rule_add;
 out:
         return err;
 
-out_fib6_default_rule_add:
-        fib_rules_cleanup_ops(net->ipv6.fib6_rules_ops);
 out_fib6_rules_ops:
-        kfree(net->ipv6.fib6_rules_ops);
+        fib_rules_unregister(ops);
         goto out;
 }
 
 static void fib6_rules_net_exit(struct net *net)
 {
         fib_rules_unregister(net->ipv6.fib6_rules_ops);
-        kfree(net->ipv6.fib6_rules_ops);
 }
 
 static struct pernet_operations fib6_rules_net_ops = {