From 0d846d206e709797a8bbe65ec648878dc2853434 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka@google.com>
Date: Tue, 16 May 2023 10:41:14 -0700
Subject: Revert "[NFC][LSAN] Move ThreadCreate into child thread"

https://bugs.chromium.org/p/chromium/issues/detail?id=1445676

This reverts commit 6d7b26ae49b9273d9aea4e53a96901caeb09efe0.
---
 compiler-rt/lib/lsan/lsan_interceptors.cpp | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

(limited to 'compiler-rt')

diff --git a/compiler-rt/lib/lsan/lsan_interceptors.cpp b/compiler-rt/lib/lsan/lsan_interceptors.cpp
index 2a35572edfec..4be34db28c77 100644
--- a/compiler-rt/lib/lsan/lsan_interceptors.cpp
+++ b/compiler-rt/lib/lsan/lsan_interceptors.cpp
@@ -415,10 +415,8 @@ INTERCEPTOR(char *, strerror, int errnum) {
 
 #if SANITIZER_POSIX
 
-template <bool Detached>
-static void *ThreadStartFunc(void *arg) {
-  u32 parent_tid = (uptr)arg;
-  uptr tid = ThreadCreate(parent_tid, Detached);
+extern "C" void *__lsan_thread_start_func(void *arg) {
+  atomic_uintptr_t *atomic_tid = (atomic_uintptr_t *)arg;
   // Wait until the last iteration to maximize the chance that we are the last
   // destructor to run.
 #if !SANITIZER_NETBSD && !SANITIZER_FREEBSD
@@ -427,8 +425,12 @@ static void *ThreadStartFunc(void *arg) {
     Report("LeakSanitizer: failed to set thread key.\n");
     Die();
   }
-#  endif
+#endif
+  int tid = 0;
+  while ((tid = atomic_load(atomic_tid, memory_order_acquire)) == 0)
+    internal_sched_yield();
   ThreadStart(tid, GetTid());
+  atomic_store(atomic_tid, 0, memory_order_release);
   auto self = GetThreadSelf();
   auto args = GetThreadArgRetval().GetArgs(self);
   void *retval = (*args.routine)(args.arg_retval);
@@ -448,7 +450,7 @@ INTERCEPTOR(int, pthread_create, void *th, void *attr,
   AdjustStackSize(attr);
   int detached = 0;
   pthread_attr_getdetachstate(attr, &detached);
-  uptr this_tid = GetCurrentThreadId();
+  atomic_uintptr_t atomic_tid = {};
   int result;
   {
     // Ignore all allocations made by pthread_create: thread stack/TLS may be
@@ -457,14 +459,18 @@ INTERCEPTOR(int, pthread_create, void *th, void *attr,
     // objects, the latter are calculated by obscure pointer arithmetic.
     ScopedInterceptorDisabler disabler;
     GetThreadArgRetval().Create(detached, {callback, param}, [&]() -> uptr {
-      result = REAL(pthread_create)(th, attr,
-                                    IsStateDetached(detached)
-                                        ? ThreadStartFunc<true>
-                                        : ThreadStartFunc<false>,
-                                    (void *)this_tid);
+      result =
+          REAL(pthread_create)(th, attr, __lsan_thread_start_func, &atomic_tid);
       return result ? 0 : *(uptr *)(th);
     });
   }
+  if (result == 0) {
+    int tid = ThreadCreate(GetCurrentThreadId(), IsStateDetached(detached));
+    CHECK_NE(tid, kMainTid);
+    atomic_store(&atomic_tid, tid, memory_order_release);
+    while (atomic_load(&atomic_tid, memory_order_acquire) != 0)
+      internal_sched_yield();
+  }
   if (attr == &myattr)
     pthread_attr_destroy(&myattr);
   return result;
-- 
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