[Bf-blender-cvs] [ff5630b7faf] blender-v3.0-release: Fix T92740: Missing lock around the image CacheLimiter

[Jesse Yurkovich]

Commit: ff5630b7fafec56d9b1187ee42e8b786b62cb498
Author: Jesse Yurkovich
Date:   Thu Nov 4 20:58:32 2021 -0700
Branches: blender-v3.0-release
https://developer.blender.org/rBff5630b7fafec56d9b1187ee42e8b786b62cb498

Fix T92740: Missing lock around the image CacheLimiter

A recent change exposed this long-standing race. Simply protect the
MEM_CacheLimiter with its lock now. Additionally, guard against
unmanaging an already destroyed cache handle.

Ref T92740, T92838

===================================================================

M	source/blender/imbuf/intern/moviecache.c

===================================================================

diff --git a/source/blender/imbuf/intern/moviecache.c b/source/blender/imbuf/intern/moviecache.c
index 4f316150e10..1bc0a4e628d 100644
--- a/source/blender/imbuf/intern/moviecache.c
+++ b/source/blender/imbuf/intern/moviecache.c
@@ -122,7 +122,12 @@ static void moviecache_valfree(void *val)
 
   PRINT("%s: cache '%s' free item %p buffer %p\n", __func__, cache->name, item, item->ibuf);
 
-  MEM_CacheLimiter_unmanage(item->c_handle);
+  BLI_mutex_lock(&limitor_lock);
+  if (item->c_handle) {
+    MEM_CacheLimiter_unmanage(item->c_handle);
+  }
+  BLI_mutex_unlock(&limitor_lock);
+
   if (item->ibuf) {
     IMB_freeImBuf(item->ibuf);
   }