From 84f17f32ad3561a0be9717733e320ecb8592b92f Mon Sep 17 00:00:00 2001
From: Francis Ricci <francisjricci@gmail.com>
Date: Tue, 11 Apr 2017 19:57:12 +0000
Subject: [PATCH] Don't delete lsan thread-local data until it's no longer
 required

Summary:
The routines for thread destruction in the thread registry require
the lsan thread index, which is stored in pthread tls on OS X.
This means that we need to make sure that the lsan tls isn't destroyed
until after the thread registry tls. This change ensures that we
don't delete the lsan tls until we've finished destroying the thread
in the registry, ensuring that the destructor for the lsan tls runs
after the destructor for the thread registry tls.

This patch also adds a check to ensure that the thread ID is valid before
returning it in GetThreadID(), to ensure that the above behavior
is working correctly.

Reviewers: dvyukov, kubamracek, kcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31884

llvm-svn: 299978
---
 compiler-rt/lib/lsan/lsan_common_mac.cc | 18 ++++++++++++++++--
 compiler-rt/lib/lsan/lsan_thread.cc     |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/lib/lsan/lsan_common_mac.cc b/compiler-rt/lib/lsan/lsan_common_mac.cc
index 5fd2b89afd8a6..549595da51bbe 100644
--- a/compiler-rt/lib/lsan/lsan_common_mac.cc
+++ b/compiler-rt/lib/lsan/lsan_common_mac.cc
@@ -33,7 +33,17 @@ typedef struct {
 static pthread_key_t key;
 static pthread_once_t key_once = PTHREAD_ONCE_INIT;
 
-static void make_tls_key() { CHECK_EQ(pthread_key_create(&key, NULL), 0); }
+// The main thread destructor requires the current thread id,
+// so we can't destroy it until it's been used and reset to invalid tid
+void restore_tid_data(void *ptr) {
+  thread_local_data_t *data = (thread_local_data_t *)ptr;
+  if (data->current_thread_id != kInvalidTid)
+    pthread_setspecific(key, data);
+}
+
+static void make_tls_key() {
+  CHECK_EQ(pthread_key_create(&key, restore_tid_data), 0);
+}
 
 static thread_local_data_t *get_tls_val(bool alloc) {
   pthread_once(&key_once, make_tls_key);
@@ -65,7 +75,11 @@ void EnableInThisThread() {
   --*disable_counter;
 }
 
-u32 GetCurrentThread() { return get_tls_val(true)->current_thread_id; }
+u32 GetCurrentThread() {
+  thread_local_data_t *data = get_tls_val(false);
+  CHECK(data);
+  return data->current_thread_id;
+}
 
 void SetCurrentThread(u32 tid) { get_tls_val(true)->current_thread_id = tid; }
 
diff --git a/compiler-rt/lib/lsan/lsan_thread.cc b/compiler-rt/lib/lsan/lsan_thread.cc
index ebec6cdbf1468..09eeb9c249821 100644
--- a/compiler-rt/lib/lsan/lsan_thread.cc
+++ b/compiler-rt/lib/lsan/lsan_thread.cc
@@ -92,6 +92,7 @@ void ThreadStart(u32 tid, uptr os_id) {
 
 void ThreadFinish() {
   thread_registry->FinishThread(GetCurrentThread());
+  SetCurrentThread(kInvalidTid);
 }
 
 ThreadContext *CurrentThreadContext() {