1 files changed, 21 insertions, 42 deletions

diff --git a/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_thread_list.h b/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_thread_list.h
index 914b632d9776..e596bde36662 100644
--- a/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_thread_list.h
+++ b/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_thread_list.h
@@ -66,40 +66,6 @@ static uptr RingBufferSize() {
   return 0;
 }
 
-struct ThreadListHead {
-  Thread *list_;
-
-  ThreadListHead() : list_(nullptr) {}
-
-  void Push(Thread *t) {
-    t->next_ = list_;
-    list_ = t;
-  }
-
-  Thread *Pop() {
-    Thread *t = list_;
-    if (t)
-      list_ = t->next_;
-    return t;
-  }
-
-  void Remove(Thread *t) {
-    Thread **cur = &list_;
-    while (*cur != t) cur = &(*cur)->next_;
-    CHECK(*cur && "thread not found");
-    *cur = (*cur)->next_;
-  }
-
-  template <class CB>
-  void ForEach(CB cb) {
-    Thread *t = list_;
-    while (t) {
-      cb(t);
-      t = t->next_;
-    }
-  }
-};
-
 struct ThreadStats {
   uptr n_live_threads;
   uptr total_stack_size;
@@ -123,14 +89,15 @@ class HwasanThreadList {
     Thread *t;
     {
       SpinMutexLock l(&list_mutex_);
-      t = free_list_.Pop();
-      if (t) {
+      if (!free_list_.empty()) {
+        t = free_list_.back();
+        free_list_.pop_back();
         uptr start = (uptr)t - ring_buffer_size_;
         internal_memset((void *)start, 0, ring_buffer_size_ + sizeof(Thread));
       } else {
         t = AllocThread();
       }
-      live_list_.Push(t);
+      live_list_.push_back(t);
     }
     t->Init((uptr)t - ring_buffer_size_, ring_buffer_size_);
     AddThreadStats(t);
@@ -142,12 +109,24 @@ class HwasanThreadList {
     ReleaseMemoryPagesToOS(start, start + thread_alloc_size_);
   }
 
+  void RemoveThreadFromLiveList(Thread *t) {
+    for (Thread *&t2 : live_list_)
+      if (t2 == t) {
+        // To remove t2, copy the last element of the list in t2's position, and
+        // pop_back(). This works even if t2 is itself the last element.
+        t2 = live_list_.back();
+        live_list_.pop_back();
+        return;
+      }
+    CHECK(0 && "thread not found in live list");
+  }
+
   void ReleaseThread(Thread *t) {
     RemoveThreadStats(t);
     t->Destroy();
     SpinMutexLock l(&list_mutex_);
-    live_list_.Remove(t);
-    free_list_.Push(t);
+    RemoveThreadFromLiveList(t);
+    free_list_.push_back(t);
     DontNeedThread(t);
   }
 
@@ -166,7 +145,7 @@ class HwasanThreadList {
   template <class CB>
   void VisitAllLiveThreads(CB cb) {
     SpinMutexLock l(&list_mutex_);
-    live_list_.ForEach(cb);
+    for (Thread *t : live_list_) cb(t);
   }
 
   void AddThreadStats(Thread *t) {
@@ -201,8 +180,8 @@ class HwasanThreadList {
   uptr ring_buffer_size_;
   uptr thread_alloc_size_;
 
-  ThreadListHead free_list_;
-  ThreadListHead live_list_;
+  InternalMmapVector<Thread *> free_list_;
+  InternalMmapVector<Thread *> live_list_;
   SpinMutex list_mutex_;
 
   ThreadStats stats_;