[tsan] Improve suppression for tzset

When running under TSAN disable inlining of LocalTime
helper so we can write a suppression using its name.

Fixes #61396

TEST=ci

Cq-Include-Trybots: luci.dart.try:vm-tsan-linux-release-x64-try,vm-tsan-linux-release-arm64-try
Change-Id: I9f07572b5b597343dbc61554c4f287eac630f047
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/446720
Commit-Queue: Slava Egorov <[email protected]>
Reviewed-by: Alexander Markov <[email protected]>

Author: mraleph

build/sanitizers/sanitizer_options.cc

@@ -29,7 +29,7 @@ SANITIZER_HOOK_ATTRIBUTE const char* __tsan_default_suppressions() {
 # In some environments tzset_internal is not symbolized correctly so we
 # also suppress the closest caller which is properly symbolized.
 race:tzset_internal
-race:dart::DN_HelperDateTime_timeZoneOffsetInSeconds
+race:dart::LocalTime
 )";
 }
 #endif  // defined(USING_THREAD_SANITIZER) && defined(DART_HOST_OS_LINUX)

runtime/vm/os_linux.cc

@@ -415,10 +415,33 @@ intptr_t OS::ProcessId() {
   return static_cast<intptr_t>(getpid());
 }
 
+// TSAN detects data races inside tzset implementation because it does not
+// understand low-level synchronization primitives used by libc. We would
+// like to suppress these false positives, however writing a suppression
+// targeting tzset is hard because
+//
+// 1. On our bots TSAN fails to properly symbolize
+// libc symbols (meaning that we can't simply suppress tzset itself).
+// 2. libc is compiled without frame-pointers so TzSet caller is missing
+// from the stack trace.
+//
+// To work-around both issues we create a simple wrapper over TzSet with is
+// not inlined to guarantee that LocalTime (the caller of this wrapper)
+// appears in the stack trace and we can suppress false positive occurring
+// inside it.
+#if defined(USING_THREAD_SANITIZER)
+DART_NOINLINE
+#else
+DART_FORCE_INLINE
+#endif
+static void TzSet() {
+  tzset();
+}
+
 static bool LocalTime(int64_t seconds_since_epoch, tm* tm_result) {
   time_t seconds = static_cast<time_t>(seconds_since_epoch);
   if (seconds != seconds_since_epoch) return false;
-  tzset();  // Not guaranteed by POSIX to be called by `localtime_r`.
+  TzSet();  // Not guaranteed by POSIX to be called by `localtime_r`.
   struct tm* error_code = localtime_r(&seconds, tm_result);
   return error_code != nullptr;
 }