--- /dev/null
+/*
+ * 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/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; /* Interval between stats, in seconds. */
+ /* Defaults to "only at end of test". */
+static int verbose; /* Print more debug info. */
+static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
+static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
+
+module_param(nreaders, int, 0);
+MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
+module_param(stat_interval, int, 0);
+MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
+module_param(verbose, bool, 0);
+MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
+module_param(test_no_idle_hz, bool, 0);
+MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
+module_param(shuffle_interval, int, 0);
+MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
+#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;
+static struct task_struct *shuffler_task;
+
+#define RCU_TORTURE_PIPE_LEN 10
+
+struct rcu_torture {
+ struct rcu_head rtort_rcu;
+ int rtort_pipe_count;
+ struct list_head rtort_free;
+ int rtort_mbtest;
+};
+
+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;
+atomic_t n_rcu_torture_mberror;
+atomic_t n_rcu_torture_error;
+
+/*
+ * Allocate an element from the rcu_tortures pool.
+ */
+static struct rcu_torture *
+rcu_torture_alloc(void)
+{
+ struct list_head *p;
+
+ spin_lock_bh(&rcu_torture_lock);
+ if (list_empty(&rcu_torture_freelist)) {
+ atomic_inc(&n_rcu_torture_alloc_fail);
+ spin_unlock_bh(&rcu_torture_lock);
+ return NULL;
+ }
+ atomic_inc(&n_rcu_torture_alloc);
+ p = rcu_torture_freelist.next;
+ list_del_init(p);
+ spin_unlock_bh(&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_bh(&rcu_torture_lock);
+ list_add_tail(&p->rtort_free, &rcu_torture_freelist);
+ spin_unlock_bh(&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) {
+ rp->rtort_mbtest = 0;
+ 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");
+ set_user_nice(current, 19);
+
+ 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;
+ rp->rtort_mbtest = 1;
+ 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");
+ set_user_nice(current, 19);
+
+ 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;
+ }
+ if (p->rtort_mbtest == 0)
+ atomic_inc(&n_rcu_torture_mberror);
+ 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_possible_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 "
+ "rtmbe: %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),
+ atomic_read(&n_rcu_torture_mberror));
+ if (atomic_read(&n_rcu_torture_mberror) != 0)
+ cnt += sprintf(&page[cnt], " !!!");
+ cnt += sprintf(&page[cnt], "\nrcutorture: ");
+ if (i > 1) {
+ cnt += sprintf(&page[cnt], "!!! ");
+ atomic_inc(&n_rcu_torture_error);
+ }
+ 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 int rcu_idle_cpu; /* Force all torture tasks off this CPU */
+
+/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
+ * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
+ */
+void rcu_torture_shuffle_tasks(void)
+{
+ cpumask_t tmp_mask = CPU_MASK_ALL;
+ int i;
+
+ lock_cpu_hotplug();
+
+ /* No point in shuffling if there is only one online CPU (ex: UP) */
+ if (num_online_cpus() == 1) {
+ unlock_cpu_hotplug();
+ return;
+ }
+
+ if (rcu_idle_cpu != -1)
+ cpu_clear(rcu_idle_cpu, tmp_mask);
+
+ set_cpus_allowed(current, tmp_mask);
+
+ if (reader_tasks != NULL) {
+ for (i = 0; i < nrealreaders; i++)
+ if (reader_tasks[i])
+ set_cpus_allowed(reader_tasks[i], tmp_mask);
+ }
+
+ if (writer_task)
+ set_cpus_allowed(writer_task, tmp_mask);
+
+ if (stats_task)
+ set_cpus_allowed(stats_task, tmp_mask);
+
+ if (rcu_idle_cpu == -1)
+ rcu_idle_cpu = num_online_cpus() - 1;
+ else
+ rcu_idle_cpu--;
+
+ unlock_cpu_hotplug();
+}
+
+/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
+ * system to become idle at a time and cut off its timer ticks. This is meant
+ * to test the support for such tickless idle CPU in RCU.
+ */
+static int
+rcu_torture_shuffle(void *arg)
+{
+ VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
+ do {
+ schedule_timeout_interruptible(shuffle_interval * HZ);
+ rcu_torture_shuffle_tasks();
+ } while (!kthread_should_stop());
+ VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
+ return 0;
+}
+
+static inline void
+rcu_torture_print_module_parms(char *tag)
+{
+ printk(KERN_ALERT TORTURE_FLAG "--- %s: nreaders=%d "
+ "stat_interval=%d verbose=%d test_no_idle_hz=%d "
+ "shuffle_interval = %d\n",
+ tag, nrealreaders, stat_interval, verbose, test_no_idle_hz,
+ shuffle_interval);
+}
+
+static void
+rcu_torture_cleanup(void)
+{
+ int i;
+
+ fullstop = 1;
+ if (shuffler_task != NULL) {
+ VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
+ kthread_stop(shuffler_task);
+ }
+ shuffler_task = NULL;
+
+ 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. */
+ rcu_barrier();
+
+ rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
+ if (atomic_read(&n_rcu_torture_error))
+ rcu_torture_print_module_parms("End of test: FAILURE");
+ else
+ rcu_torture_print_module_parms("End of test: SUCCESS");
+}
+
+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();
+ rcu_torture_print_module_parms("Start of test");
+ fullstop = 0;
+
+ /* Set up the freelist. */
+
+ INIT_LIST_HEAD(&rcu_torture_freelist);
+ for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
+ rcu_tortures[i].rtort_mbtest = 0;
+ 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);
+ atomic_set(&n_rcu_torture_mberror, 0);
+ atomic_set(&n_rcu_torture_error, 0);
+ for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
+ atomic_set(&rcu_torture_wcount[i], 0);
+ for_each_possible_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;
+ }
+ }
+ if (test_no_idle_hz) {
+ rcu_idle_cpu = num_online_cpus() - 1;
+ /* Create the shuffler thread */
+ shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
+ "rcu_torture_shuffle");
+ if (IS_ERR(shuffler_task)) {
+ firsterr = PTR_ERR(shuffler_task);
+ VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
+ shuffler_task = NULL;
+ goto unwind;
+ }
+ }
+ return 0;
+
+unwind:
+ rcu_torture_cleanup();
+ return firsterr;
+}
+
+module_init(rcu_torture_init);
+module_exit(rcu_torture_cleanup);
git://git.onelab.eu / linux-2.6.git / blobdiff