commit 4302d51868daa94e81d3002073e9265397b2e444
author Niklas Haas <git@haasn.dev> Mon Nov 08 14:58:50 2021 +0100
committer Niklas Haas <git@haasn.dev> Mon Nov 08 15:00:28 2021 +0100
tree 1a5eef53e6e2c82465918873fb924b8d6e455b6e
parent 3971424207e27a662d4416eedfb68e18ff287350

Don't release global mutex before initialize/finalize is done

Otherwise this can race with other threads for access to the fields it's
supposed to be initializing/finalizing.

For example, imagine another thread is calling ShInitialize() while the
first thread is calling ShFinalize() - the finalize function would
destroy the state at the same time as the initialize function is trying
to initialize it.

Holding on to the global lock for the entire function prevents all of
these failure modes.

glslang/MachineIndependent/ShaderLang.cpp

diff --git a/glslang/MachineIndependent/ShaderLang.cpp b/glslang/MachineIndependent/ShaderLang.cpp
index d02eae6..a2dd71c 100644
--- a/glslang/MachineIndependent/ShaderLang.cpp
+++ b/glslang/MachineIndependent/ShaderLang.cpp
@@ -1343,7 +1343,6 @@
 
     glslang::GetGlobalLock();
     ++NumberOfClients;
-    glslang::ReleaseGlobalLock();
 
     if (PerProcessGPA == nullptr)
         PerProcessGPA = new TPoolAllocator();
@@ -1353,6 +1352,7 @@
     glslang::HlslScanContext::fillInKeywordMap();
 #endif
 
+    glslang::ReleaseGlobalLock();
     return 1;
 }
 
@@ -1415,9 +1415,10 @@
     --NumberOfClients;
     assert(NumberOfClients >= 0);
     bool finalize = NumberOfClients == 0;
-    glslang::ReleaseGlobalLock();
-    if (! finalize)
+    if (! finalize) {
+        glslang::ReleaseGlobalLock();
         return 1;
+    }
 
     for (int version = 0; version < VersionCount; ++version) {
         for (int spvVersion = 0; spvVersion < SpvVersionCount; ++spvVersion) {
@@ -1455,6 +1456,7 @@
     glslang::HlslScanContext::deleteKeywordMap();
 #endif
 
+    glslang::ReleaseGlobalLock();
     return 1;
 }