Move futex wakeup model to nto1-selective

[userspace-rcu.git] / futex-wakeup / nto1-selective / futex.spin

diff --git a/futex-wakeup/nto1-selective/futex.spin b/futex-wakeup/nto1-selective/futex.spin
new file mode 100644 (file)
index 0000000..c68a77b
--- /dev/null
+++ b/futex-wakeup/nto1-selective/futex.spin
@@ -0,0 +1,159 @@
+/*
+ * futex.spin: Promela code to validate futex wakeup algorithm.
+ *
+ * Algorithm verified :
+ *
+ * queue = 0;
+ * waiting = 0;
+ * gp_futex = 0;
+ * gp = 1;
+ *
+ *                          Waker
+ *                          while (1) {
+ *                            this.queue = gp;
+ *                            if (this.waiting == 1) {
+ *                              this.waiting = 0;
+ *                              if (gp_futex == -1) {
+ *                                gp_futex = 0;
+ *                                futex_wake = 1;
+ *                              }
+ *                            }
+ *                          }
+ *
+ * Waiter
+ * in_registry = 1;
+ * while (1) {
+ *   gp_futex = -1;
+ *   waiting |= (queue != gp);
+ *   in_registry &= (queue != gp);
+ *   if (all in_registry == 0) {
+ * progress:
+ *     gp_futex = 0;
+ *     gp = !gp;
+ *     restart;
+ *   } else {
+ *     futex_wake = (gp_futex == -1 ? 0 : 1);
+ *     while (futex_wake == 0) { }
+ *   }
+ *   queue = 0;
+ * }
+ *
+ * By testing progress, i.e. [] <> !np_, we check that an infinite sequence
+ * of update_counter_and_wait (and consequently of synchronize_rcu) will
+ * not block.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers
+ */
+
+#define get_pid()       (_pid)
+
+int queue[2] = 0;
+int waiting[2] = 0;
+int futex_wake = 0;
+int gp_futex = 0;
+int gp = 1;
+int in_registry[2] = 0;
+
+active [2] proctype waker()
+{
+       assert(get_pid() < 2);
+
+       do
+       :: 1 ->
+               queue[get_pid()] = gp;
+       
+               if
+               :: (waiting[get_pid()] == 1) ->
+                       waiting[get_pid()] = 0;
+                       if
+                       :: (gp_futex == -1) ->
+                               gp_futex = 0;
+#ifndef INJ_QUEUE_NO_WAKE
+                               futex_wake = 1;
+#endif
+                       :: else ->
+                               skip;
+                       fi;
+               fi;
+       od;
+}
+
+
+active proctype waiter()
+{
+restart:
+       in_registry[0] = 1;
+       in_registry[1] = 1;
+       do
+       :: 1 ->
+#if (!defined(INJ_LATE_DEC) && !defined(INJ_INVERT_WAITING_VS_GP_FUTEX))
+               gp_futex = -1;
+#endif
+               if
+               :: (in_registry[0] == 1 && queue[0] != gp) ->
+                       waiting[0] = 1;
+                :: else ->
+                       skip;
+               fi;
+               if
+               :: (in_registry[1] == 1 && queue[1] != gp) ->
+                       waiting[1] = 1;
+                :: else ->
+                       skip;
+               fi;
+
+               if
+               :: (in_registry[0] == 1 && queue[0] == gp) ->
+                       in_registry[0] = 0;
+               :: else ->
+                       skip;
+               fi;
+               if
+               :: (in_registry[1] == 1 && queue[1] == gp) ->
+                       in_registry[1] = 0;
+               :: else ->
+                       skip;
+               fi;
+#ifdef INJ_INVERT_WAITING_VS_GP_FUTEX
+               gp_futex = -1;
+#endif
+
+               if
+               :: (in_registry[0] == 0 && in_registry[1] == 0) ->
+progress:
+#ifndef INJ_LATE_DEC
+                       gp_futex = 0;
+#endif
+                       gp = !gp;
+                       goto restart;
+               :: else ->
+#ifdef INJ_LATE_DEC
+                       gp_futex = -1;
+#endif
+                       futex_wake = gp_futex + 1;
+                       do
+                       :: 1 ->
+                               if
+                               :: (futex_wake == 0) ->
+                                       skip;
+                               :: else ->
+                                       break;
+                               fi;
+                       od;
+               fi;
+       od;
+}