rcutorture: Abstract rcu_torture_random()

Because rcu_torture_random() will be used by the locking equivalent to
rcutorture, pull it out into its own module.  This new module cannot
be separately configured, instead, use the Kconfig "select" statement
from the Kconfig options of tests depending on it.

Suggested-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/kernel/torture.c b/kernel/torture.c
new file mode 100644
index 000000000000..c82c70f7828e
--- /dev/null
+++ b/kernel/torture.c
@@ -0,0 +1,71 @@
+/*
+ * Common functions for in-kernel torture tests.
+ *
+ * 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, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2014
+ *
+ * Author: Paul E. McKenney <paulmck@us.ibm.com>
+ *	Based on kernel/rcu/torture.c.
+ */
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/moduleparam.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/freezer.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+#include <linux/trace_clock.h>
+#include <asm/byteorder.h>
+#include <linux/torture.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
+
+#define TORTURE_RANDOM_MULT	39916801  /* prime */
+#define TORTURE_RANDOM_ADD	479001701 /* prime */
+#define TORTURE_RANDOM_REFRESH	10000
+
+/*
+ * Crude but fast random-number generator.  Uses a linear congruential
+ * generator, with occasional help from cpu_clock().
+ */
+unsigned long
+torture_random(struct torture_random_state *trsp)
+{
+	if (--trsp->trs_count < 0) {
+		trsp->trs_state += (unsigned long)local_clock();
+		trsp->trs_count = TORTURE_RANDOM_REFRESH;
+	}
+	trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
+		TORTURE_RANDOM_ADD;
+	return swahw32(trsp->trs_state);
+}
+EXPORT_SYMBOL_GPL(torture_random);