Adapt upstream patches fixing potential deadlock in tcmalloc after fork.

third_party/tcmalloc/chromium/src/static_vars.cc

Index: third_party/tcmalloc/chromium/src/static_vars.cc
diff --git a/third_party/tcmalloc/chromium/src/static_vars.cc b/third_party/tcmalloc/chromium/src/static_vars.cc
index 6fc852a82d1f2edb6e48f8d6ce2f100f80b4feab..ece565d586b9dbb418b79086066a909f11c5c689 100644
--- a/third_party/tcmalloc/chromium/src/static_vars.cc
+++ b/third_party/tcmalloc/chromium/src/static_vars.cc
@@ -36,9 +36,32 @@
 #include "internal_logging.h"  // for CHECK_CONDITION
 #include "common.h"
 #include "sampler.h"           // for Sampler
+#include "base/googleinit.h"
+#include "maybe_threads.h"
 
 namespace tcmalloc {
 
+#if defined(HAVE_FORK) && defined(HAVE_PTHREAD) && !defined(__APPLE__)
+
+// These following two functions are registered via pthread_atfork to make
+// sure the central_cache locks remain in a consisten state in the forked
+// version of the thread.
+
+void CentralCacheLockAll()
+{
+  Static::pageheap_lock()->Lock();
+  for (int i = 0; i < kNumClasses; ++i)
+    Static::central_cache()[i].Lock();
+}
+
+void CentralCacheUnlockAll()
+{
+  for (int i = 0; i < kNumClasses; ++i)
+    Static::central_cache()[i].Unlock();
+  Static::pageheap_lock()->Unlock();
+}
+#endif
+
 SpinLock Static::pageheap_lock_(SpinLock::LINKER_INITIALIZED);
 SizeMap Static::sizemap_;
 CentralFreeListPadded Static::central_cache_[kNumClasses];
@@ -70,4 +93,19 @@ void Static::InitStaticVars() {
   Sampler::InitStatics();
 }
 
+
+#if defined(HAVE_FORK) && defined(HAVE_PTHREAD) && !defined(__APPLE__)
+
+static inline
+void SetupAtForkLocksHandler()
+{
+  perftools_pthread_atfork(
+    CentralCacheLockAll,    // parent calls before fork
+    CentralCacheUnlockAll,  // parent calls after fork
+    CentralCacheUnlockAll); // child calls after fork
+}
+REGISTER_MODULE_INITIALIZER(tcmalloc_fork_handler, SetupAtForkLocksHandler());
+
+#endif
+
 }  // namespace tcmalloc