From e5a9eceff45a673f5dba0a6fa4e5125eeb16b933 Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Tue, 29 Nov 2016 17:23:53 +0200
Subject: [PATCH] Cache: Fix prev/next twiddling

---
 server/modules/filter/cache/lrustorage.cc | 5 +++--
 server/modules/filter/cache/lrustorage.h  | 4 +++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/server/modules/filter/cache/lrustorage.cc b/server/modules/filter/cache/lrustorage.cc
index 3e3711cd8..2c5c63e67 100644
--- a/server/modules/filter/cache/lrustorage.cc
+++ b/server/modules/filter/cache/lrustorage.cc
@@ -51,7 +51,7 @@ cache_result_t LRUStorage::do_get_value(const CACHE_KEY& key,
         {
             if (ptail_ == i->second)
             {
-                ptail_ = i->second->next();
+                ptail_ = i->second->prev();
             }
 
             phead_ = i->second->prepend(phead_);
@@ -217,6 +217,7 @@ LRUStorage::Node* LRUStorage::free_lru()
     if (free_node_data(ptail_))
     {
         pnode = ptail_;
+        ptail_ = ptail_->remove();
     }
 
     return pnode;
@@ -280,7 +281,7 @@ bool LRUStorage::free_node_data(Node* pnode)
 
     NodesPerKey::iterator i = nodes_per_key_.find(*pkey);
 
-    if (i != nodes_per_key_.end())
+    if (i == nodes_per_key_.end())
     {
         MXS_ERROR("Item in LRU list was not found in key mapping.");
     }
diff --git a/server/modules/filter/cache/lrustorage.h b/server/modules/filter/cache/lrustorage.h
index 59bc57e2f..15ef0a9f3 100644
--- a/server/modules/filter/cache/lrustorage.h
+++ b/server/modules/filter/cache/lrustorage.h
@@ -119,8 +119,10 @@ private:
                     pnode->pprev_->pnext_ = this;
                 }
 
-                pnode->pprev_ = this;
+                pprev_ = pnode->pprev_;
                 pnext_ = pnode;
+
+                pnode->pprev_ = this;
             }
 
             return this;