From f9ec62cb3acd62a089f71eab4185ba1310296ea1 Mon Sep 17 00:00:00 2001
From: Kostya Serebryany <kcc@google.com>
Date: Fri, 7 Sep 2018 00:16:55 +0000
Subject: [PATCH] [hwasan] change the thread list so that main_thread can also
 be removed

llvm-svn: 341610
---
 compiler-rt/lib/hwasan/hwasan_thread.cc | 16 ++++++++++------
 compiler-rt/lib/hwasan/hwasan_thread.h  |  4 ++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/compiler-rt/lib/hwasan/hwasan_thread.cc b/compiler-rt/lib/hwasan/hwasan_thread.cc
index aa60d199af0a..1d008982d4d7 100644
--- a/compiler-rt/lib/hwasan/hwasan_thread.cc
+++ b/compiler-rt/lib/hwasan/hwasan_thread.cc
@@ -24,7 +24,7 @@ static u32 RandomSeed() {
   return seed;
 }
 
-Thread *Thread::main_thread;
+Thread *Thread::thread_list_head;
 SpinMutex Thread::thread_list_mutex;
 Thread::ThreadStats Thread::thread_stats;
 
@@ -33,22 +33,26 @@ void Thread::InsertIntoThreadList(Thread *t) {
   SpinMutexLock l(&thread_list_mutex);
   thread_stats.n_live_threads++;
   thread_stats.total_stack_size += t->stack_size();
-  if (!main_thread) {
-    main_thread = t;
+  if (!thread_list_head) {
+    thread_list_head = t;
     return;
   }
-  Thread *last = main_thread;
+  Thread *last = thread_list_head;
   while (last->next_)
     last = last->next_;
   last->next_ = t;
 }
 
 void Thread::RemoveFromThreadList(Thread *t) {
-  if (t == main_thread) return;  // Do nothing (happens due to pthread_exit).
   SpinMutexLock l(&thread_list_mutex);
   thread_stats.n_live_threads--;
   thread_stats.total_stack_size -= t->stack_size();
-  Thread *prev = main_thread;
+  if (t == thread_list_head) {
+    thread_list_head = t->next_;
+    t->next_ = nullptr;
+    return;
+  }
+  Thread *prev = thread_list_head;
   Thread *cur = prev->next_;
   CHECK(cur);
   while (cur) {
diff --git a/compiler-rt/lib/hwasan/hwasan_thread.h b/compiler-rt/lib/hwasan/hwasan_thread.h
index 6b41f51d8b53..6a27ba6f2166 100644
--- a/compiler-rt/lib/hwasan/hwasan_thread.h
+++ b/compiler-rt/lib/hwasan/hwasan_thread.h
@@ -62,7 +62,7 @@ class Thread {
   template <class CB>
   static void VisitAllLiveThreads(CB cb) {
     SpinMutexLock l(&thread_list_mutex);
-    Thread *t = main_thread;
+    Thread *t = thread_list_head;
     while (t) {
       cb(t);
       t = t->next_;
@@ -113,7 +113,7 @@ class Thread {
   static void RemoveFromThreadList(Thread *t);
   Thread *next_;  // All live threads form a linked list.
   static SpinMutex thread_list_mutex;
-  static Thread *main_thread;
+  static Thread *thread_list_head;
   static ThreadStats thread_stats;
 
   u64 unique_id_;  // counting from zero.