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>

1 files changed, 12 insertions, 10 deletions

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();
 }