libitm: Fix privatization safety during upgrades to serial mode.

	libitm/
	* beginend.cc (GTM::gtm_thread::restart): Add and handle
	finish_serial_upgrade parameter.
	* libitm.h (GTM::gtm_thread::restart): Adapt declaration.
	* config/linux/rwlock.cc (GTM::gtm_rwlock::write_lock_generic):
	Don't unset reader flag.
	(GTM::gtm_rwlock::write_upgrade_finish): New.
	* config/posix/rwlock.cc: Same.
	* config/linux/rwlock.h (GTM::gtm_rwlock::write_upgrade_finish):
	Declare.
	* config/posix/rwlock.h: Same.
	* method-serial.cc (GTM::gtm_thread::serialirr_mode): Unset reader
	flag after commit or after rollback when restarting.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@182675 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 9 insertions, 11 deletions

diff --git a/libitm/method-serial.cc b/libitm/method-serial.cc
index 5e85653a2f4..bf7982650ff 100644
--- a/libitm/method-serial.cc
+++ b/libitm/method-serial.cc
@@ -239,7 +239,6 @@ void
 GTM::gtm_thread::serialirr_mode ()
 {
   struct abi_dispatch *disp = abi_disp ();
-  bool need_restart = true;
 
   if (this->state & STATE_SERIAL)
     {
@@ -254,7 +253,6 @@ GTM::gtm_thread::serialirr_mode ()
       bool ok = disp->trycommit (priv_time);
       // Given that we're already serial, the trycommit better work.
       assert (ok);
-      need_restart = false;
     }
   else if (serial_lock.write_upgrade (this))
     {
@@ -263,18 +261,18 @@ GTM::gtm_thread::serialirr_mode ()
       // would do for an outermost commit.
       // We have successfully upgraded to serial mode, so we don't need to
       // ensure privatization safety for other transactions here.
+      // However, we are still a reader (wrt. privatization safety) until we
+      // have either committed or restarted, so finish the upgrade after that.
       gtm_word priv_time = 0;
-      if (disp->trycommit (priv_time))
-	need_restart = false;
+      if (!disp->trycommit (priv_time))
+        restart (RESTART_SERIAL_IRR, true);
+      gtm_thread::serial_lock.write_upgrade_finish(this);
     }
-
-  if (need_restart)
-    restart (RESTART_SERIAL_IRR);
   else
-    {
-      this->state |= (STATE_SERIAL | STATE_IRREVOCABLE);
-      set_abi_disp (dispatch_serialirr ());
-    }
+    restart (RESTART_SERIAL_IRR, false);
+
+  this->state |= (STATE_SERIAL | STATE_IRREVOCABLE);
+  set_abi_disp (dispatch_serialirr ());
 }
 
 void ITM_REGPARM