Make memoryPageSize() functions thread-safe.

These used a static for caching the computation, but didn't use a static initializer. This meant there was a race between the check for zero and the assignment. Bug: b/153803432 Change-Id: Id5b91050ced0b8d4811eb32ffed24885816ade7a Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/43909Tested-by: Ben Clayton <bclayton@google.com> Reviewed-by: Nicolas Capens <nicolascapens@google.com> Kokoro-Result: kokoro <noreply+kokoro@google.com>

Make memoryPageSize() functions thread-safe.
ab983012 · Ben Clayton · 4d23aa35 · ab983012 · ab983012
Commit ab983012 authored Apr 15, 2020 by Ben Clayton
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Showing with 8 additions and 14 deletions

ExecutableMemory.cpp src/Reactor/ExecutableMemory.cpp +4 -7

Memory.cpp src/System/Memory.cpp +4 -7

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--- a/src/Reactor/ExecutableMemory.cpp
+++ b/src/Reactor/ExecutableMemory.cpp
@@ -199,18 +199,15 @@ zx_vm_option_t permissionsToZxVmOptions(int permissions)
 size_t memoryPageSize()
 {
-	static int pageSize = 0;
+	static int pageSize = [] {
-	if(pageSize == 0)
-	{
 #if defined(_WIN32)
 		SYSTEM_INFO systemInfo;
 		GetSystemInfo(&systemInfo);
-		pageSize = systemInfo.dwPageSize;
+		return systemInfo.dwPageSize;
 #else
-		pageSize = sysconf(_SC_PAGESIZE);
+		return sysconf(_SC_PAGESIZE);
 #endif
-	}
+	}();
 	return pageSize;
 }

--- a/src/System/Memory.cpp
+++ b/src/System/Memory.cpp
@@ -91,18 +91,15 @@ void *allocateRaw(size_t bytes, size_t alignment)
 size_t memoryPageSize()
 {
-	static int pageSize = 0;
+	static int pageSize = [] {
-	if(pageSize == 0)
-	{
 #if defined(_WIN32)
 		SYSTEM_INFO systemInfo;
 		GetSystemInfo(&systemInfo);
-		pageSize = systemInfo.dwPageSize;
+		return systemInfo.dwPageSize;
 #else
-		pageSize = sysconf(_SC_PAGESIZE);
+		return sysconf(_SC_PAGESIZE);
 #endif
-	}
+	}();
 	return pageSize;
 }