X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=urcu-qsbr-selective-wakeup%2Ffutex.spin;fp=urcu-qsbr-selective-wakeup%2Ffutex.spin;h=556f96fad7b175aa5bc78879aa25e99917ab3680;hb=2e33016fc8b527cb35e466c1e093f0d0bd7ed296;hp=0000000000000000000000000000000000000000;hpb=ef781656a07c5a52fd09508336994f29c8bb8cb3;p=urcu.git

diff --git a/urcu-qsbr-selective-wakeup/futex.spin b/urcu-qsbr-selective-wakeup/futex.spin
new file mode 100644
index 0000000..556f96f
--- /dev/null
+++ b/urcu-qsbr-selective-wakeup/futex.spin
@@ -0,0 +1,163 @@
+/*
+ * futex.spin: Promela code to validate n wakers to 1 waiter selective
+ * futex wakeup algorithm.
+ *
+ * In this model, waker threads are told whether they are still being
+ * waited on, and skip the futex wakeup if not.
+ *
+ * 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) 2009-2011 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;
+}