[XFRM] Optimize policy dumping

This change optimizes the dumping of Security policies.

1) Before this change ..
speedopolis:~# time ./ip xf pol

real    0m22.274s
user    0m0.000s
sys     0m22.269s

2) Turn off sub-policies

speedopolis:~# ./ip xf pol

real    0m13.496s
user    0m0.000s
sys     0m13.493s

i suppose the above is to be expected

3) With this change ..
speedopolis:~# time ./ip x policy

real    0m7.901s
user    0m0.008s
sys     0m7.896s

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index f6c77bd..4f04222 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -860,33 +860,12 @@ EXPORT_SYMBOL(xfrm_policy_flush);
 int xfrm_policy_walk(u8 type, int (*func)(struct xfrm_policy *, int, int, void*),
                     void *data)
 {
-       struct xfrm_policy *pol;
+       struct xfrm_policy *pol, *last = NULL;
        struct hlist_node *entry;
-       int dir, count, error;
+       int dir, last_dir = 0, count, error;
 
        read_lock_bh(&xfrm_policy_lock);
        count = 0;
-       for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
-               struct hlist_head *table = xfrm_policy_bydst[dir].table;
-               int i;
-
-               hlist_for_each_entry(pol, entry,
-                                    &xfrm_policy_inexact[dir], bydst) {
-                       if (pol->type == type)
-                               count++;
-               }
-               for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
-                       hlist_for_each_entry(pol, entry, table + i, bydst) {
-                               if (pol->type == type)
-                                       count++;
-                       }
-               }
-       }
-
-       if (count == 0) {
-               error = -ENOENT;
-               goto out;
-       }
 
        for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
                struct hlist_head *table = xfrm_policy_bydst[dir].table;
@@ -896,21 +875,37 @@ int xfrm_policy_walk(u8 type, int (*func)(struct xfrm_policy *, int, int, void*)
                                     &xfrm_policy_inexact[dir], bydst) {
                        if (pol->type != type)
                                continue;
-                       error = func(pol, dir % XFRM_POLICY_MAX, --count, data);
-                       if (error)
-                               goto out;
+                       if (last) {
+                               error = func(last, last_dir % XFRM_POLICY_MAX,
+                                            count, data);
+                               if (error)
+                                       goto out;
+                       }
+                       last = pol;
+                       last_dir = dir;
+                       count++;
                }
                for (i = xfrm_policy_bydst[dir].hmask; i >= 0; i--) {
                        hlist_for_each_entry(pol, entry, table + i, bydst) {
                                if (pol->type != type)
                                        continue;
-                               error = func(pol, dir % XFRM_POLICY_MAX, --count, data);
-                               if (error)
-                                       goto out;
+                               if (last) {
+                                       error = func(last, last_dir % XFRM_POLICY_MAX,
+                                                    count, data);
+                                       if (error)
+                                               goto out;
+                               }
+                               last = pol;
+                               last_dir = dir;
+                               count++;
                        }
                }
        }
-       error = 0;
+       if (count == 0) {
+               error = -ENOENT;
+               goto out;
+       }
+       error = func(last, last_dir % XFRM_POLICY_MAX, 0, data);
 out:
        read_unlock_bh(&xfrm_policy_lock);
        return error;