[tsan] Lock/Unlock allocator and stacks on fork (llvm#96600)

We do that for other Sanitizers, and we
should do the same for TSAN.
There are know deadlocks reports here.

compiler-rt/lib/tsan/rtl/tsan_mman.cpp

@@ -17,6 +17,7 @@
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_errno.h"
 #include "sanitizer_common/sanitizer_placement_new.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
 #include "tsan_flags.h"
 #include "tsan_interface.h"
 #include "tsan_report.h"
@@ -119,9 +120,18 @@ ScopedGlobalProcessor::~ScopedGlobalProcessor() {
 void AllocatorLockBeforeFork() SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
   global_proc()->internal_alloc_mtx.Lock();
   InternalAllocatorLock();
+#if !SANITIZER_APPLE
+  // OS X allocates from hooks, see 6a3958247a.
+  allocator()->ForceLock();
+  StackDepotLockBeforeFork();
+#endif
 }
 
 void AllocatorUnlockAfterFork(bool child) SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
+#if !SANITIZER_APPLE
+  StackDepotUnlockAfterFork(child);
+  allocator()->ForceUnlock();
+#endif
   InternalAllocatorUnlock();
   global_proc()->internal_alloc_mtx.Unlock();
 }

compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c

@@ -6,9 +6,6 @@
 // FIXME: It probably hangs on this platform.
 // UNSUPPORTED: ppc
 
-// FIXME: TSAN does not lock allocator.
-// UNSUPPORTED: tsan
-
 // FIXME: False stack overflow report
 // UNSUPPORTED: android && asan