Thread suspension: Implement for Linux

src/trusted/service_runtime/win/thread_suspension.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <windows.h>
 
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/src/shared/platform/nacl_sync_checked.h"
 #include "native_client/src/trusted/service_runtime/nacl_app_thread.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
 
 
+void NaClAppThreadSetSuspendState(struct NaClAppThread *natp,
+                                  enum NaClSuspendState old_state,
+                                  enum NaClSuspendState new_state) {
+  NaClXMutexLock(&natp->mu);
+  while ((natp->suspend_state & NACL_APP_THREAD_SUSPENDING) != 0) {
+    /*
+     * We are being suspended, but SuspendThread() has not taken effect yet.
+     */
+    NaClXCondVarWait(&natp->cv, &natp->mu);
+  }
+  DCHECK(natp->suspend_state == old_state);
+  natp->suspend_state = new_state;
+  NaClXMutexUnlock(&natp->mu);
+}
+
 void NaClUntrustedThreadSuspend(struct NaClAppThread *natp) {
   enum NaClSuspendState old_state;
 
   /*
    * Note that if we are being called from a NaCl syscall (which is
    * likely), natp could be the thread we are running in.  That is
    * fine, because this thread will be in the
    * NACL_APP_THREAD_TRUSTED state, and so we will not call
    * SuspendThread() on it.
    */
@@ skipping 87 matching lines @@
   size_t index;
   for (index = 0; index < nap->threads.num_entries; index++) {
     struct NaClAppThread *natp = NaClGetThreadMu(nap, (int) index);
     if (natp != NULL) {
       NaClUntrustedThreadResume(natp);
     }
   }
 
   NaClXMutexUnlock(&nap->threads_mu);
 }