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>

include/linux/torture.h

@@ -0,0 +1,47 @@
+/*
+ * 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 IBM Corporation, 2014
+ *
+ * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ */
+
+#ifndef __LINUX_TORTURE_H
+#define __LINUX_TORTURE_H
+
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/spinlock.h>
+#include <linux/threads.h>
+#include <linux/cpumask.h>
+#include <linux/seqlock.h>
+#include <linux/lockdep.h>
+#include <linux/completion.h>
+#include <linux/debugobjects.h>
+#include <linux/bug.h>
+#include <linux/compiler.h>
+
+struct torture_random_state {
+	unsigned long trs_state;
+	long trs_count;
+};
+
+#define DEFINE_TORTURE_RANDOM(name) struct torture_random_state name = { 0, 0 }
+
+unsigned long torture_random(struct torture_random_state *trsp);
+
+#endif /* __LINUX_TORTURE_H */

kernel/Makefile

@@ -93,6 +93,7 @@ obj-$(CONFIG_PADATA) += padata.o
 obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
 obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
+obj-$(CONFIG_TORTURE_TEST) += torture.o
 
 $(obj)/configs.o: $(obj)/config_data.h
 

kernel/rcu/Makefile

@@ -1,5 +1,5 @@
 obj-y += update.o srcu.o
-obj-$(CONFIG_RCU_TORTURE_TEST) += torture.o
+obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_TREE_RCU) += tree.o
 obj-$(CONFIG_TREE_PREEMPT_RCU) += tree.o
 obj-$(CONFIG_TREE_RCU_TRACE) += tree_trace.o

kernel/rcu/torture.c → kernel/rcu/rcutorture.c

@@ -48,6 +48,7 @@
 #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> and Josh Triplett <josh@freedesktop.org>");
@@ -320,32 +321,6 @@ rcu_torture_free(struct rcu_torture *p)
 	spin_unlock_bh(&rcu_torture_lock);
 }
 
-struct rcu_random_state {
-	unsigned long rrs_state;
-	long rrs_count;
-};
-
-#define RCU_RANDOM_MULT 39916801  /* prime */
-#define RCU_RANDOM_ADD	479001701 /* prime */
-#define RCU_RANDOM_REFRESH 10000
-
-#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
-
-/*
- * Crude but fast random-number generator.  Uses a linear congruential
- * generator, with occasional help from cpu_clock().
- */
-static unsigned long
-rcu_random(struct rcu_random_state *rrsp)
-{
-	if (--rrsp->rrs_count < 0) {
-		rrsp->rrs_state += (unsigned long)local_clock();
-		rrsp->rrs_count = RCU_RANDOM_REFRESH;
-	}
-	rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
-	return swahw32(rrsp->rrs_state);
-}
-
 static void
 rcu_stutter_wait(const char *title)
 {
@@ -365,7 +340,7 @@ rcu_stutter_wait(const char *title)
 struct rcu_torture_ops {
 	void (*init)(void);
 	int (*readlock)(void);
-	void (*read_delay)(struct rcu_random_state *rrsp);
+	void (*read_delay)(struct torture_random_state *rrsp);
 	void (*readunlock)(int idx);
 	int (*completed)(void);
 	void (*deferred_free)(struct rcu_torture *p);
@@ -392,7 +367,7 @@ static int rcu_torture_read_lock(void) __acquires(RCU)
 	return 0;
 }
 
-static void rcu_read_delay(struct rcu_random_state *rrsp)
+static void rcu_read_delay(struct torture_random_state *rrsp)
 {
 	const unsigned long shortdelay_us = 200;
 	const unsigned long longdelay_ms = 50;
@@ -401,12 +376,13 @@ static void rcu_read_delay(struct rcu_random_state *rrsp)
 	 * period, and we want a long delay occasionally to trigger
 	 * force_quiescent_state. */
 
-	if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
+	if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 		mdelay(longdelay_ms);
-	if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
+	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 		udelay(shortdelay_us);
 #ifdef CONFIG_PREEMPT
-	if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
+	if (!preempt_count() &&
+	    !(torture_random(rrsp) % (nrealreaders * 20000)))
 		preempt_schedule();  /* No QS if preempt_disable() in effect */
 #endif
 }
@@ -530,7 +506,7 @@ static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 	return srcu_read_lock(&srcu_ctl);
 }
 
-static void srcu_read_delay(struct rcu_random_state *rrsp)
+static void srcu_read_delay(struct torture_random_state *rrsp)
 {
 	long delay;
 	const long uspertick = 1000000 / HZ;
@@ -538,7 +514,8 @@ static void srcu_read_delay(struct rcu_random_state *rrsp)
 
 	/* We want there to be long-running readers, but not all the time. */
 
-	delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
+	delay = torture_random(rrsp) %
+		(nrealreaders * 2 * longdelay * uspertick);
 	if (!delay)
 		schedule_timeout_interruptible(longdelay);
 	else
@@ -802,7 +779,7 @@ rcu_torture_writer(void *arg)
 	struct rcu_torture *rp;
 	struct rcu_torture *rp1;
 	struct rcu_torture *old_rp;
-	static DEFINE_RCU_RANDOM(rand);
+	static DEFINE_TORTURE_RANDOM(rand);
 
 	VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 	set_user_nice(current, 19);
@@ -813,7 +790,7 @@ rcu_torture_writer(void *arg)
 		if (rp == NULL)
 			continue;
 		rp->rtort_pipe_count = 0;
-		udelay(rcu_random(&rand) & 0x3ff);
+		udelay(torture_random(&rand) & 0x3ff);
 		old_rp = rcu_dereference_check(rcu_torture_current,
 					       current == writer_task);
 		rp->rtort_mbtest = 1;
@@ -826,7 +803,7 @@ rcu_torture_writer(void *arg)
 			atomic_inc(&rcu_torture_wcount[i]);
 			old_rp->rtort_pipe_count++;
 			if (gp_normal == gp_exp)
-				exp = !!(rcu_random(&rand) & 0x80);
+				exp = !!(torture_random(&rand) & 0x80);
 			else
 				exp = gp_exp;
 			if (!exp) {
@@ -868,19 +845,19 @@ rcu_torture_writer(void *arg)
 static int
 rcu_torture_fakewriter(void *arg)
 {
-	DEFINE_RCU_RANDOM(rand);
+	DEFINE_TORTURE_RANDOM(rand);
 
 	VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 	set_user_nice(current, 19);
 
 	do {
-		schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
-		udelay(rcu_random(&rand) & 0x3ff);
+		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
+		udelay(torture_random(&rand) & 0x3ff);
 		if (cur_ops->cb_barrier != NULL &&
-		    rcu_random(&rand) % (nfakewriters * 8) == 0) {
+		    torture_random(&rand) % (nfakewriters * 8) == 0) {
 			cur_ops->cb_barrier();
 		} else if (gp_normal == gp_exp) {
-			if (rcu_random(&rand) & 0x80)
+			if (torture_random(&rand) & 0x80)
 				cur_ops->sync();
 			else
 				cur_ops->exp_sync();
@@ -921,7 +898,7 @@ static void rcu_torture_timer(unsigned long unused)
 	int idx;
 	int completed;
 	int completed_end;
-	static DEFINE_RCU_RANDOM(rand);
+	static DEFINE_TORTURE_RANDOM(rand);
 	static DEFINE_SPINLOCK(rand_lock);
 	struct rcu_torture *p;
 	int pipe_count;
@@ -980,7 +957,7 @@ rcu_torture_reader(void *arg)
 	int completed;
 	int completed_end;
 	int idx;
-	DEFINE_RCU_RANDOM(rand);
+	DEFINE_TORTURE_RANDOM(rand);
 	struct rcu_torture *p;
 	int pipe_count;
 	struct timer_list t;
@@ -1389,7 +1366,7 @@ rcu_torture_onoff(void *arg)
 	int cpu;
 	unsigned long delta;
 	int maxcpu = -1;
-	DEFINE_RCU_RANDOM(rand);
+	DEFINE_TORTURE_RANDOM(rand);
 	int ret;
 	unsigned long starttime;
 
@@ -1403,7 +1380,7 @@ rcu_torture_onoff(void *arg)
 		VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
 	}
 	while (!kthread_should_stop()) {
-		cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
+		cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
 		if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
 			if (verbose)
 				pr_alert("%s" TORTURE_FLAG

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);

lib/Kconfig.debug

@@ -1141,9 +1141,14 @@ config SPARSE_RCU_POINTER
 
 	 Say N if you are unsure.
 
+config TORTURE_TEST
+	tristate
+	default n
+
 config RCU_TORTURE_TEST
 	tristate "torture tests for RCU"
 	depends on DEBUG_KERNEL
+	select TORTURE_TEST
 	default n
 	help
 	  This option provides a kernel module that runs torture tests