acl-plugin: rework the optimization 7383, fortify acl-plugin memory behavior (VPP-910)

The further prolonged testing from testbed that reported VPP-910
has uncovered a couple of deeper issues with optimization from
7384, and the usage of subscripts rather than vec_elt_at_index()
allowed to hide a couple of further errors in the code.
Also, the current acl-plugin behavior of using the global
heap for its dynamic data is problematic - it makes
the troubleshooting much harder by potentially spreading
the problem around.

Based on this experience, this commits makes a few changes to fix
the issues seen, also improving the serviceability of the acl-plugin
code for the future:

- Use separate mheaps for any ACL-related control plane
operations and separate for the hash lookup datastructures,
to compartmentalize any memory-related issues for the ACL plugin.

- Ensure vec_elt_at_index() usage throughout the hash_lookup.c file.

- Use vectors rather than raw memory for storing the "ordinary" ACL rules.

- Rework the optimization from 7384 to use a separate tail pointer
rather than overloading the "prev" field.

- Make get_session_ptr() more conservative and adjust is_valid_session_ptr
accordingly

Change-Id: Ifda85193f361de5ed3782a4acd39622bd33c5830
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
(cherry picked from commit bd9c5ffe39e9ce61db95d74d150e07d738f24da1)

1 files changed, 4 insertions, 4 deletions

diff --git a/src/plugins/acl/hash_lookup_types.h b/src/plugins/acl/hash_lookup_types.h
index 1848c5ffc6a..fbc9777b83d 100644
--- a/src/plugins/acl/hash_lookup_types.h
+++ b/src/plugins/acl/hash_lookup_types.h
@@ -53,14 +53,14 @@ typedef struct {
    */
   u32 next_applied_entry_index;
   /*
-   * previous entry in the ring list of the chained ones.
+   * previous entry in the list of the chained ones,
+   * if ~0 then this is entry in the hash.
    */
   u32 prev_applied_entry_index;
   /*
-   * 1 if it is the very first entry in the list,
-   * referenced from the hash.
+   * chain tail, if this is the first entry
    */
-  u8 is_first_entry;
+  u32 tail_applied_entry_index;
   /*
    * Action of this applied ACE
    */