/*
* Read-Copy Update /proc-based torture test facility
*
* 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) IBM Corporation, 2005
*
* Authors: Paul E. McKenney <paulmck@us.ibm.com>
*
* See also: Documentation/RCU/torture.txt
*/
#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/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <asm/atomic.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/rcuref.h>
#include <linux/cpu.h>
#include <linux/random.h>
#include <linux/delay.h>
#include <linux/byteorder/swabb.h>
#include <linux/stat.h>
MODULE_LICENSE("GPL");
static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */
static int stat_interval = 0; /* Interval between stats, in seconds. */
/* Defaults to "only at end of test". */
static int verbose = 0; /* Print more debug info. */
MODULE_PARM(nreaders, "i");
MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
MODULE_PARM(stat_interval, "i");
MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
MODULE_PARM(verbose, "i");
MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
#define TORTURE_FLAG "rcutorture: "
#define PRINTK_STRING(s) \
do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
#define VERBOSE_PRINTK_STRING(s) \
do { if (verbose) printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
#define VERBOSE_PRINTK_ERRSTRING(s) \
do { if (verbose) printk(KERN_ALERT TORTURE_FLAG "!!! " s "\n"); } while (0)
static char printk_buf[4096];
static int nrealreaders;
static struct task_struct *writer_task;
static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
#define RCU_TORTURE_PIPE_LEN 10
struct rcu_torture {
struct rcu_head rtort_rcu;
int rtort_pipe_count;
struct list_head rtort_free;
};
static int fullstop = 0; /* stop generating callbacks at test end. */
static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture *rcu_torture_current = NULL;
static long rcu_torture_current_version = 0;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
{ 0 };
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
{ 0 };
static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
atomic_t n_rcu_torture_alloc;
atomic_t n_rcu_torture_alloc_fail;
atomic_t n_rcu_torture_free;
/*
* Allocate an element from the rcu_tortures pool.
*/
struct rcu_torture *
rcu_torture_alloc(void)
{
struct list_head *p;
spin_lock(&rcu_torture_lock);
if (list_empty(&rcu_torture_freelist)) {
atomic_inc(&n_rcu_torture_alloc_fail);
spin_unlock(&rcu_torture_lock);
return NULL;
}
atomic_inc(&n_rcu_torture_alloc);
p = rcu_torture_freelist.next;
list_del_init(p);
spin_unlock(&rcu_torture_lock);
return container_of(p, struct rcu_torture, rtort_free);
}
/*
* Free an element to the rcu_tortures pool.
*/
static void
rcu_torture_free(struct rcu_torture *p)
{
atomic_inc(&n_rcu_torture_free);
spin_lock(&rcu_torture_lock);
list_add_tail(&p->rtort_free, &rcu_torture_freelist);
spin_unlock(&rcu_torture_lock);
}
static void
rcu_torture_cb(struct rcu_head *p)
{
int i;
struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
if (fullstop) {
/* Test is ending, just drop callbacks on the floor. */
/* The next initialization will pick up the pieces. */
return;
}
i = rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN)
rcu_torture_free(rp);
else
call_rcu(p, rcu_torture_cb);
}
struct rcu_random_state {
unsigned long rrs_state;
unsigned 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 get_random_bytes().
*/
static long
rcu_random(struct rcu_random_state *rrsp)
{
long refresh;
if (--rrsp->rrs_count < 0) {
get_random_bytes(&refresh, sizeof(refresh));
rrsp->rrs_state += refresh;
rrsp->rrs_count = RCU_RANDOM_REFRESH;
}
rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
return swahw32(rrsp->rrs_state);
}
/*
* RCU torture writer kthread. Repeatedly substitutes a new structure
* for that pointed to by rcu_torture_current, freeing the old structure
* after a series of grace periods (the "pipeline").
*/
static int
rcu_torture_writer(void *arg)
{
int i;
long oldbatch = rcu_batches_completed();
struct rcu_torture *rp;
struct rcu_torture *old_rp;
static DEFINE_RCU_RANDOM(rand);
VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
do {
schedule_timeout_uninterruptible(1);
if (rcu_batches_completed() == oldbatch)
continue;
if ((rp = rcu_torture_alloc()) == NULL)
continue;
rp->rtort_pipe_count = 0;
udelay(rcu_random(&rand) & 0x3ff);
old_rp = rcu_torture_current;
rcu_assign_pointer(rcu_torture_current, rp);
smp_wmb();
if (old_rp != NULL) {
i = old_rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
old_rp->rtort_pipe_count++;
call_rcu(&old_rp->rtort_rcu, rcu_torture_cb);
}
rcu_torture_current_version++;
oldbatch = rcu_batches_completed();
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
}
/*
* RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
* counter in the element should never be greater than 1, otherwise, the
* RCU implementation is broken.
*/
static int
rcu_torture_reader(void *arg)
{
int completed;
DEFINE_RCU_RANDOM(rand);
struct rcu_torture *p;
int pipe_count;
VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
do {
rcu_read_lock();
completed = rcu_batches_completed();
p = rcu_dereference(rcu_torture_current);
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
rcu_read_unlock();
schedule_timeout_interruptible(HZ);
continue;
}
udelay(rcu_random(&rand) & 0x7f);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_count)[pipe_count];
completed = rcu_batches_completed() - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
}
++__get_cpu_var(rcu_torture_batch)[completed];
preempt_enable();
rcu_read_unlock();
schedule();
} while (!kthread_should_stop() && !fullstop);
VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
while (!kthread_should_stop())
schedule_timeout_uninterruptible(1);
return 0;
}
/*
* Create an RCU-torture statistics message in the specified buffer.
*/
static int
rcu_torture_printk(char *page)
{
int cnt = 0;
int cpu;
int i;
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
for_each_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
}
}
for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
if (pipesummary[i] != 0)
break;
}
cnt += sprintf(&page[cnt], "rcutorture: ");
cnt += sprintf(&page[cnt],
"rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d",
rcu_torture_current,
rcu_torture_current_version,
list_empty(&rcu_torture_freelist),
atomic_read(&n_rcu_torture_alloc),
atomic_read(&n_rcu_torture_alloc_fail),
atomic_read(&n_rcu_torture_free));
cnt += sprintf(&page[cnt], "\nrcutorture: ");
if (i > 1)
cnt += sprintf(&page[cnt], "!!! ");
cnt += sprintf(&page[cnt], "Reader Pipe: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
cnt += sprintf(&page[cnt], "\nrcutorture: ");
cnt += sprintf(&page[cnt], "Reader Batch: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++)
cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
cnt += sprintf(&page[cnt], "\nrcutorture: ");
cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
cnt += sprintf(&page[cnt], " %d",
atomic_read(&rcu_torture_wcount[i]));
}
cnt += sprintf(&page[cnt], "\n");
return cnt;
}
/*
* Print torture statistics. Caller must ensure that there is only
* one call to this function at a given time!!! This is normally
* accomplished by relying on the module system to only have one copy
* of the module loaded, and then by giving the rcu_torture_stats
* kthread full control (or the init/cleanup functions when rcu_torture_stats
* thread is not running).
*/
static void
rcu_torture_stats_print(void)
{
int cnt;
cnt = rcu_torture_printk(printk_buf);
printk(KERN_ALERT "%s", printk_buf);
}
/*
* Periodically prints torture statistics, if periodic statistics printing
* was specified via the stat_interval module parameter.
*
* No need to worry about fullstop here, since this one doesn't reference
* volatile state or register callbacks.
*/
static int
rcu_torture_stats(void *arg)
{
VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
do {
schedule_timeout_interruptible(stat_interval * HZ);
rcu_torture_stats_print();
} while (!kthread_should_stop());
VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
return 0;
}
static void
rcu_torture_cleanup(void)
{
int i;
fullstop = 1;
if (writer_task != NULL) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
kthread_stop(writer_task);
}
writer_task = NULL;
if (reader_tasks != NULL) {
for (i = 0; i < nrealreaders; i++) {
if (reader_tasks[i] != NULL) {
VERBOSE_PRINTK_STRING(
"Stopping rcu_torture_reader task");
kthread_stop(reader_tasks[i]);
}
reader_tasks[i] = NULL;
}
kfree(reader_tasks);
reader_tasks = NULL;
}
rcu_torture_current = NULL;
if (stats_task != NULL) {
VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
kthread_stop(stats_task);
}
stats_task = NULL;
/* Wait for all RCU callbacks to fire. */
for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++)
synchronize_rcu();
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
PRINTK_STRING("--- End of test");
}
static int
rcu_torture_init(void)
{
int i;
int cpu;
int firsterr = 0;
/* Process args and tell the world that the torturer is on the job. */
if (nreaders >= 0)
nrealreaders = nreaders;
else
nrealreaders = 2 * num_online_cpus();
printk(KERN_ALERT TORTURE_FLAG
"--- Start of test: nreaders=%d stat_interval=%d verbose=%d\n",
nrealreaders, stat_interval, verbose);
fullstop = 0;
/* Set up the freelist. */
INIT_LIST_HEAD(&rcu_torture_freelist);
for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
list_add_tail(&rcu_tortures[i].rtort_free,
&rcu_torture_freelist);
}
/* Initialize the statistics so that each run gets its own numbers. */
rcu_torture_current = NULL;
rcu_torture_current_version = 0;
atomic_set(&n_rcu_torture_alloc, 0);
atomic_set(&n_rcu_torture_alloc_fail, 0);
atomic_set(&n_rcu_torture_free, 0);
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
atomic_set(&rcu_torture_wcount[i], 0);
for_each_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
per_cpu(rcu_torture_count, cpu)[i] = 0;
per_cpu(rcu_torture_batch, cpu)[i] = 0;
}
}
/* Start up the kthreads. */
VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
writer_task = kthread_run(rcu_torture_writer, NULL,
"rcu_torture_writer");
if (IS_ERR(writer_task)) {
firsterr = PTR_ERR(writer_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
writer_task = NULL;
goto unwind;
}
reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
GFP_KERNEL);
if (reader_tasks == NULL) {
VERBOSE_PRINTK_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
for (i = 0; i < nrealreaders; i++) {
VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
"rcu_torture_reader");
if (IS_ERR(reader_tasks[i])) {
firsterr = PTR_ERR(reader_tasks[i]);
VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
reader_tasks[i] = NULL;
goto unwind;
}
}
if (stat_interval > 0) {
VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
stats_task = kthread_run(rcu_torture_stats, NULL,
"rcu_torture_stats");
if (IS_ERR(stats_task)) {
firsterr = PTR_ERR(stats_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
stats_task = NULL;
goto unwind;
}
}
return 0;
unwind:
rcu_torture_cleanup();
return firsterr;
}
module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);
