drm/radeon/kms: vram sizing on certain r100 chips needs workaround.
[linux-2.6.git] / kernel / rcutorture.c
index e045021..9b4a975 100644 (file)
 #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/reboot.h>
+#include <linux/freezer.h>
 #include <linux/cpu.h>
-#include <linux/random.h>
 #include <linux/delay.h>
-#include <linux/byteorder/swabb.h>
 #include <linux/stat.h>
 #include <linux/srcu.h>
+#include <linux/slab.h>
+#include <asm/byteorder.h>
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
@@ -57,22 +58,28 @@ 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)*/
-static char *torture_type = "rcu"; /* What to torture: rcu, rcu_bh, srcu. */
+static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
+static int stutter = 5;                /* Start/stop testing interval (in sec) */
+static int irqreader = 1;      /* RCU readers from irq (timers). */
+static char *torture_type = "rcu"; /* What RCU implementation to torture. */
 
-module_param(nreaders, int, 0);
+module_param(nreaders, int, 0444);
 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
-module_param(nfakewriters, int, 0);
+module_param(nfakewriters, int, 0444);
 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
-module_param(stat_interval, int, 0);
+module_param(stat_interval, int, 0444);
 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
-module_param(verbose, bool, 0);
+module_param(verbose, bool, 0444);
 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
-module_param(test_no_idle_hz, bool, 0);
+module_param(test_no_idle_hz, bool, 0444);
 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
-module_param(shuffle_interval, int, 0);
+module_param(shuffle_interval, int, 0444);
 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
-module_param(torture_type, charp, 0);
+module_param(stutter, int, 0444);
+MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
+module_param(irqreader, int, 0444);
+MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
+module_param(torture_type, charp, 0444);
 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 
 #define TORTURE_FLAG "-torture:"
@@ -91,6 +98,7 @@ static struct task_struct **fakewriter_tasks;
 static struct task_struct **reader_tasks;
 static struct task_struct *stats_task;
 static struct task_struct *shuffler_task;
+static struct task_struct *stutter_task;
 
 #define RCU_TORTURE_PIPE_LEN 10
 
@@ -101,7 +109,6 @@ struct rcu_torture {
        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;
@@ -117,6 +124,58 @@ static atomic_t n_rcu_torture_alloc_fail;
 static atomic_t n_rcu_torture_free;
 static atomic_t n_rcu_torture_mberror;
 static atomic_t n_rcu_torture_error;
+static long n_rcu_torture_timers = 0;
+static struct list_head rcu_torture_removed;
+static cpumask_var_t shuffle_tmp_mask;
+
+static int stutter_pause_test = 0;
+
+#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
+#define RCUTORTURE_RUNNABLE_INIT 1
+#else
+#define RCUTORTURE_RUNNABLE_INIT 0
+#endif
+int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
+
+/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
+
+#define FULLSTOP_DONTSTOP 0    /* Normal operation. */
+#define FULLSTOP_SHUTDOWN 1    /* System shutdown with rcutorture running. */
+#define FULLSTOP_RMMOD    2    /* Normal rmmod of rcutorture. */
+static int fullstop = FULLSTOP_RMMOD;
+DEFINE_MUTEX(fullstop_mutex);  /* Protect fullstop transitions and spawning */
+                               /*  of kthreads. */
+
+/*
+ * Detect and respond to a system shutdown.
+ */
+static int
+rcutorture_shutdown_notify(struct notifier_block *unused1,
+                          unsigned long unused2, void *unused3)
+{
+       mutex_lock(&fullstop_mutex);
+       if (fullstop == FULLSTOP_DONTSTOP)
+               fullstop = FULLSTOP_SHUTDOWN;
+       else
+               printk(KERN_WARNING /* but going down anyway, so... */
+                      "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
+       mutex_unlock(&fullstop_mutex);
+       return NOTIFY_DONE;
+}
+
+/*
+ * Absorb kthreads into a kernel function that won't return, so that
+ * they won't ever access module text or data again.
+ */
+static void rcutorture_shutdown_absorb(char *title)
+{
+       if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
+               printk(KERN_NOTICE
+                      "rcutorture thread %s parking due to system shutdown\n",
+                      title);
+               schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
+       }
+}
 
 /*
  * Allocate an element from the rcu_tortures pool.
@@ -164,22 +223,32 @@ struct rcu_random_state {
 
 /*
  * Crude but fast random-number generator.  Uses a linear congruential
- * generator, with occasional help from get_random_bytes().
+ * generator, with occasional help from cpu_clock().
  */
 static unsigned 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_state +=
+                       (unsigned long)cpu_clock(raw_smp_processor_id());
                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(char *title)
+{
+       while (stutter_pause_test || !rcutorture_runnable) {
+               if (rcutorture_runnable)
+                       schedule_timeout_interruptible(1);
+               else
+                       schedule_timeout_interruptible(round_jiffies_relative(HZ));
+               rcutorture_shutdown_absorb(title);
+       }
+}
+
 /*
  * Operations vector for selecting different types of tests.
  */
@@ -193,7 +262,9 @@ struct rcu_torture_ops {
        int (*completed)(void);
        void (*deferredfree)(struct rcu_torture *p);
        void (*sync)(void);
+       void (*cb_barrier)(void);
        int (*stats)(char *page);
+       int irqcapable;
        char *name;
 };
 static struct rcu_torture_ops *cur_ops = NULL;
@@ -236,7 +307,7 @@ rcu_torture_cb(struct rcu_head *p)
        int i;
        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 
-       if (fullstop) {
+       if (fullstop != FULLSTOP_DONTSTOP) {
                /* Test is ending, just drop callbacks on the floor. */
                /* The next initialization will pick up the pieces. */
                return;
@@ -266,10 +337,53 @@ static struct rcu_torture_ops rcu_ops = {
        .completed = rcu_torture_completed,
        .deferredfree = rcu_torture_deferred_free,
        .sync = synchronize_rcu,
+       .cb_barrier = rcu_barrier,
        .stats = NULL,
+       .irqcapable = 1,
        .name = "rcu"
 };
 
+static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
+{
+       int i;
+       struct rcu_torture *rp;
+       struct rcu_torture *rp1;
+
+       cur_ops->sync();
+       list_add(&p->rtort_free, &rcu_torture_removed);
+       list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
+               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;
+                       list_del(&rp->rtort_free);
+                       rcu_torture_free(rp);
+               }
+       }
+}
+
+static void rcu_sync_torture_init(void)
+{
+       INIT_LIST_HEAD(&rcu_torture_removed);
+}
+
+static struct rcu_torture_ops rcu_sync_ops = {
+       .init = rcu_sync_torture_init,
+       .cleanup = NULL,
+       .readlock = rcu_torture_read_lock,
+       .readdelay = rcu_read_delay,
+       .readunlock = rcu_torture_read_unlock,
+       .completed = rcu_torture_completed,
+       .deferredfree = rcu_sync_torture_deferred_free,
+       .sync = synchronize_rcu,
+       .cb_barrier = NULL,
+       .stats = NULL,
+       .irqcapable = 1,
+       .name = "rcu_sync"
+};
+
 /*
  * Definitions for rcu_bh torture testing.
  */
@@ -326,21 +440,37 @@ static struct rcu_torture_ops rcu_bh_ops = {
        .completed = rcu_bh_torture_completed,
        .deferredfree = rcu_bh_torture_deferred_free,
        .sync = rcu_bh_torture_synchronize,
+       .cb_barrier = rcu_barrier_bh,
        .stats = NULL,
+       .irqcapable = 1,
        .name = "rcu_bh"
 };
 
+static struct rcu_torture_ops rcu_bh_sync_ops = {
+       .init = rcu_sync_torture_init,
+       .cleanup = NULL,
+       .readlock = rcu_bh_torture_read_lock,
+       .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
+       .readunlock = rcu_bh_torture_read_unlock,
+       .completed = rcu_bh_torture_completed,
+       .deferredfree = rcu_sync_torture_deferred_free,
+       .sync = rcu_bh_torture_synchronize,
+       .cb_barrier = NULL,
+       .stats = NULL,
+       .irqcapable = 1,
+       .name = "rcu_bh_sync"
+};
+
 /*
  * Definitions for srcu torture testing.
  */
 
 static struct srcu_struct srcu_ctl;
-static struct list_head srcu_removed;
 
 static void srcu_torture_init(void)
 {
        init_srcu_struct(&srcu_ctl);
-       INIT_LIST_HEAD(&srcu_removed);
+       rcu_sync_torture_init();
 }
 
 static void srcu_torture_cleanup(void)
@@ -349,7 +479,7 @@ static void srcu_torture_cleanup(void)
        cleanup_srcu_struct(&srcu_ctl);
 }
 
-static int srcu_torture_read_lock(void)
+static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 {
        return srcu_read_lock(&srcu_ctl);
 }
@@ -367,7 +497,7 @@ static void srcu_read_delay(struct rcu_random_state *rrsp)
                schedule_timeout_interruptible(longdelay);
 }
 
-static void srcu_torture_read_unlock(int idx)
+static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 {
        srcu_read_unlock(&srcu_ctl, idx);
 }
@@ -377,27 +507,6 @@ static int srcu_torture_completed(void)
        return srcu_batches_completed(&srcu_ctl);
 }
 
-static void srcu_torture_deferred_free(struct rcu_torture *p)
-{
-       int i;
-       struct rcu_torture *rp;
-       struct rcu_torture *rp1;
-
-       synchronize_srcu(&srcu_ctl);
-       list_add(&p->rtort_free, &srcu_removed);
-       list_for_each_entry_safe(rp, rp1, &srcu_removed, rtort_free) {
-               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;
-                       list_del(&rp->rtort_free);
-                       rcu_torture_free(rp);
-               }
-       }
-}
-
 static void srcu_torture_synchronize(void)
 {
        synchronize_srcu(&srcu_ctl);
@@ -427,14 +536,71 @@ static struct rcu_torture_ops srcu_ops = {
        .readdelay = srcu_read_delay,
        .readunlock = srcu_torture_read_unlock,
        .completed = srcu_torture_completed,
-       .deferredfree = srcu_torture_deferred_free,
+       .deferredfree = rcu_sync_torture_deferred_free,
        .sync = srcu_torture_synchronize,
+       .cb_barrier = NULL,
        .stats = srcu_torture_stats,
        .name = "srcu"
 };
 
-static struct rcu_torture_ops *torture_ops[] =
-       { &rcu_ops, &rcu_bh_ops, &srcu_ops, NULL };
+/*
+ * Definitions for sched torture testing.
+ */
+
+static int sched_torture_read_lock(void)
+{
+       preempt_disable();
+       return 0;
+}
+
+static void sched_torture_read_unlock(int idx)
+{
+       preempt_enable();
+}
+
+static int sched_torture_completed(void)
+{
+       return 0;
+}
+
+static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
+{
+       call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
+}
+
+static void sched_torture_synchronize(void)
+{
+       synchronize_sched();
+}
+
+static struct rcu_torture_ops sched_ops = {
+       .init = rcu_sync_torture_init,
+       .cleanup = NULL,
+       .readlock = sched_torture_read_lock,
+       .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
+       .readunlock = sched_torture_read_unlock,
+       .completed = sched_torture_completed,
+       .deferredfree = rcu_sched_torture_deferred_free,
+       .sync = sched_torture_synchronize,
+       .cb_barrier = rcu_barrier_sched,
+       .stats = NULL,
+       .irqcapable = 1,
+       .name = "sched"
+};
+
+static struct rcu_torture_ops sched_ops_sync = {
+       .init = rcu_sync_torture_init,
+       .cleanup = NULL,
+       .readlock = sched_torture_read_lock,
+       .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
+       .readunlock = sched_torture_read_unlock,
+       .completed = sched_torture_completed,
+       .deferredfree = rcu_sync_torture_deferred_free,
+       .sync = sched_torture_synchronize,
+       .cb_barrier = NULL,
+       .stats = NULL,
+       .name = "sched_sync"
+};
 
 /*
  * RCU torture writer kthread.  Repeatedly substitutes a new structure
@@ -463,7 +629,7 @@ rcu_torture_writer(void *arg)
                rp->rtort_mbtest = 1;
                rcu_assign_pointer(rcu_torture_current, rp);
                smp_wmb();
-               if (old_rp != NULL) {
+               if (old_rp) {
                        i = old_rp->rtort_pipe_count;
                        if (i > RCU_TORTURE_PIPE_LEN)
                                i = RCU_TORTURE_PIPE_LEN;
@@ -473,8 +639,10 @@ rcu_torture_writer(void *arg)
                }
                rcu_torture_current_version++;
                oldbatch = cur_ops->completed();
-       } while (!kthread_should_stop() && !fullstop);
+               rcu_stutter_wait("rcu_torture_writer");
+       } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
+       rcutorture_shutdown_absorb("rcu_torture_writer");
        while (!kthread_should_stop())
                schedule_timeout_uninterruptible(1);
        return 0;
@@ -496,15 +664,63 @@ rcu_torture_fakewriter(void *arg)
                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
                udelay(rcu_random(&rand) & 0x3ff);
                cur_ops->sync();
-       } while (!kthread_should_stop() && !fullstop);
+               rcu_stutter_wait("rcu_torture_fakewriter");
+       } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 
        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
+       rcutorture_shutdown_absorb("rcu_torture_fakewriter");
        while (!kthread_should_stop())
                schedule_timeout_uninterruptible(1);
        return 0;
 }
 
 /*
+ * RCU torture reader from timer handler.  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 void rcu_torture_timer(unsigned long unused)
+{
+       int idx;
+       int completed;
+       static DEFINE_RCU_RANDOM(rand);
+       static DEFINE_SPINLOCK(rand_lock);
+       struct rcu_torture *p;
+       int pipe_count;
+
+       idx = cur_ops->readlock();
+       completed = cur_ops->completed();
+       p = rcu_dereference(rcu_torture_current);
+       if (p == NULL) {
+               /* Leave because rcu_torture_writer is not yet underway */
+               cur_ops->readunlock(idx);
+               return;
+       }
+       if (p->rtort_mbtest == 0)
+               atomic_inc(&n_rcu_torture_mberror);
+       spin_lock(&rand_lock);
+       cur_ops->readdelay(&rand);
+       n_rcu_torture_timers++;
+       spin_unlock(&rand_lock);
+       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 = cur_ops->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();
+       cur_ops->readunlock(idx);
+}
+
+/*
  * 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
@@ -518,11 +734,18 @@ rcu_torture_reader(void *arg)
        DEFINE_RCU_RANDOM(rand);
        struct rcu_torture *p;
        int pipe_count;
+       struct timer_list t;
 
        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
        set_user_nice(current, 19);
+       if (irqreader && cur_ops->irqcapable)
+               setup_timer_on_stack(&t, rcu_torture_timer, 0);
 
        do {
+               if (irqreader && cur_ops->irqcapable) {
+                       if (!timer_pending(&t))
+                               mod_timer(&t, 1);
+               }
                idx = cur_ops->readlock();
                completed = cur_ops->completed();
                p = rcu_dereference(rcu_torture_current);
@@ -551,8 +774,12 @@ rcu_torture_reader(void *arg)
                preempt_enable();
                cur_ops->readunlock(idx);
                schedule();
-       } while (!kthread_should_stop() && !fullstop);
+               rcu_stutter_wait("rcu_torture_reader");
+       } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
+       rcutorture_shutdown_absorb("rcu_torture_reader");
+       if (irqreader && cur_ops->irqcapable)
+               del_timer_sync(&t);
        while (!kthread_should_stop())
                schedule_timeout_uninterruptible(1);
        return 0;
@@ -583,20 +810,22 @@ rcu_torture_printk(char *page)
        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
        cnt += sprintf(&page[cnt],
                       "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
-                      "rtmbe: %d",
+                      "rtmbe: %d nt: %ld",
                       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));
+                      atomic_read(&n_rcu_torture_mberror),
+                      n_rcu_torture_timers);
        if (atomic_read(&n_rcu_torture_mberror) != 0)
                cnt += sprintf(&page[cnt], " !!!");
        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
        if (i > 1) {
                cnt += sprintf(&page[cnt], "!!! ");
                atomic_inc(&n_rcu_torture_error);
+               WARN_ON_ONCE(1);
        }
        cnt += sprintf(&page[cnt], "Reader Pipe: ");
        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
@@ -612,7 +841,7 @@ rcu_torture_printk(char *page)
                               atomic_read(&rcu_torture_wcount[i]));
        }
        cnt += sprintf(&page[cnt], "\n");
-       if (cur_ops->stats != NULL)
+       if (cur_ops->stats)
                cnt += cur_ops->stats(&page[cnt]);
        return cnt;
 }
@@ -648,6 +877,7 @@ rcu_torture_stats(void *arg)
        do {
                schedule_timeout_interruptible(stat_interval * HZ);
                rcu_torture_stats_print();
+               rcutorture_shutdown_absorb("rcu_torture_stats");
        } while (!kthread_should_stop());
        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
        return 0;
@@ -660,46 +890,48 @@ static int rcu_idle_cpu;  /* Force all torture tasks off this CPU */
  */
 static void rcu_torture_shuffle_tasks(void)
 {
-       cpumask_t tmp_mask = CPU_MASK_ALL;
        int i;
 
-       lock_cpu_hotplug();
+       cpumask_setall(shuffle_tmp_mask);
+       get_online_cpus();
 
        /* No point in shuffling if there is only one online CPU (ex: UP) */
        if (num_online_cpus() == 1) {
-               unlock_cpu_hotplug();
+               put_online_cpus();
                return;
        }
 
        if (rcu_idle_cpu != -1)
-               cpu_clear(rcu_idle_cpu, tmp_mask);
+               cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
 
-       set_cpus_allowed(current, tmp_mask);
+       set_cpus_allowed_ptr(current, shuffle_tmp_mask);
 
-       if (reader_tasks != NULL) {
+       if (reader_tasks) {
                for (i = 0; i < nrealreaders; i++)
                        if (reader_tasks[i])
-                               set_cpus_allowed(reader_tasks[i], tmp_mask);
+                               set_cpus_allowed_ptr(reader_tasks[i],
+                                                    shuffle_tmp_mask);
        }
 
-       if (fakewriter_tasks != NULL) {
+       if (fakewriter_tasks) {
                for (i = 0; i < nfakewriters; i++)
                        if (fakewriter_tasks[i])
-                               set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
+                               set_cpus_allowed_ptr(fakewriter_tasks[i],
+                                                    shuffle_tmp_mask);
        }
 
        if (writer_task)
-               set_cpus_allowed(writer_task, tmp_mask);
+               set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
 
        if (stats_task)
-               set_cpus_allowed(stats_task, tmp_mask);
+               set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
 
        if (rcu_idle_cpu == -1)
                rcu_idle_cpu = num_online_cpus() - 1;
        else
                rcu_idle_cpu--;
 
-       unlock_cpu_hotplug();
+       put_online_cpus();
 }
 
 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
@@ -713,43 +945,86 @@ rcu_torture_shuffle(void *arg)
        do {
                schedule_timeout_interruptible(shuffle_interval * HZ);
                rcu_torture_shuffle_tasks();
+               rcutorture_shutdown_absorb("rcu_torture_shuffle");
        } while (!kthread_should_stop());
        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
        return 0;
 }
 
+/* Cause the rcutorture test to "stutter", starting and stopping all
+ * threads periodically.
+ */
+static int
+rcu_torture_stutter(void *arg)
+{
+       VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
+       do {
+               schedule_timeout_interruptible(stutter * HZ);
+               stutter_pause_test = 1;
+               if (!kthread_should_stop())
+                       schedule_timeout_interruptible(stutter * HZ);
+               stutter_pause_test = 0;
+               rcutorture_shutdown_absorb("rcu_torture_stutter");
+       } while (!kthread_should_stop());
+       VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
+       return 0;
+}
+
 static inline void
 rcu_torture_print_module_parms(char *tag)
 {
        printk(KERN_ALERT "%s" TORTURE_FLAG
                "--- %s: nreaders=%d nfakewriters=%d "
                "stat_interval=%d verbose=%d test_no_idle_hz=%d "
-               "shuffle_interval = %d\n",
+               "shuffle_interval=%d stutter=%d irqreader=%d\n",
                torture_type, tag, nrealreaders, nfakewriters,
-               stat_interval, verbose, test_no_idle_hz, shuffle_interval);
+               stat_interval, verbose, test_no_idle_hz, shuffle_interval,
+               stutter, irqreader);
 }
 
+static struct notifier_block rcutorture_nb = {
+       .notifier_call = rcutorture_shutdown_notify,
+};
+
 static void
 rcu_torture_cleanup(void)
 {
        int i;
 
-       fullstop = 1;
-       if (shuffler_task != NULL) {
+       mutex_lock(&fullstop_mutex);
+       if (fullstop == FULLSTOP_SHUTDOWN) {
+               printk(KERN_WARNING /* but going down anyway, so... */
+                      "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
+               mutex_unlock(&fullstop_mutex);
+               schedule_timeout_uninterruptible(10);
+               if (cur_ops->cb_barrier != NULL)
+                       cur_ops->cb_barrier();
+               return;
+       }
+       fullstop = FULLSTOP_RMMOD;
+       mutex_unlock(&fullstop_mutex);
+       unregister_reboot_notifier(&rcutorture_nb);
+       if (stutter_task) {
+               VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
+               kthread_stop(stutter_task);
+       }
+       stutter_task = NULL;
+       if (shuffler_task) {
                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
                kthread_stop(shuffler_task);
+               free_cpumask_var(shuffle_tmp_mask);
        }
        shuffler_task = NULL;
 
-       if (writer_task != NULL) {
+       if (writer_task) {
                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
                kthread_stop(writer_task);
        }
        writer_task = NULL;
 
-       if (reader_tasks != NULL) {
+       if (reader_tasks) {
                for (i = 0; i < nrealreaders; i++) {
-                       if (reader_tasks[i] != NULL) {
+                       if (reader_tasks[i]) {
                                VERBOSE_PRINTK_STRING(
                                        "Stopping rcu_torture_reader task");
                                kthread_stop(reader_tasks[i]);
@@ -761,9 +1036,9 @@ rcu_torture_cleanup(void)
        }
        rcu_torture_current = NULL;
 
-       if (fakewriter_tasks != NULL) {
+       if (fakewriter_tasks) {
                for (i = 0; i < nfakewriters; i++) {
-                       if (fakewriter_tasks[i] != NULL) {
+                       if (fakewriter_tasks[i]) {
                                VERBOSE_PRINTK_STRING(
                                        "Stopping rcu_torture_fakewriter task");
                                kthread_stop(fakewriter_tasks[i]);
@@ -774,18 +1049,20 @@ rcu_torture_cleanup(void)
                fakewriter_tasks = NULL;
        }
 
-       if (stats_task != NULL) {
+       if (stats_task) {
                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
                kthread_stop(stats_task);
        }
        stats_task = NULL;
 
        /* Wait for all RCU callbacks to fire.  */
-       rcu_barrier();
+
+       if (cur_ops->cb_barrier != NULL)
+               cur_ops->cb_barrier();
 
        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 
-       if (cur_ops->cleanup != NULL)
+       if (cur_ops->cleanup)
                cur_ops->cleanup();
        if (atomic_read(&n_rcu_torture_error))
                rcu_torture_print_module_parms("End of test: FAILURE");
@@ -793,27 +1070,31 @@ rcu_torture_cleanup(void)
                rcu_torture_print_module_parms("End of test: SUCCESS");
 }
 
-static int
+static int __init
 rcu_torture_init(void)
 {
        int i;
        int cpu;
        int firsterr = 0;
+       static struct rcu_torture_ops *torture_ops[] =
+               { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
+                 &srcu_ops, &sched_ops, &sched_ops_sync, };
 
-       /* Process args and tell the world that the torturer is on the job. */
+       mutex_lock(&fullstop_mutex);
 
-       for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
+       /* Process args and tell the world that the torturer is on the job. */
+       for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
                cur_ops = torture_ops[i];
-               if (strcmp(torture_type, cur_ops->name) == 0) {
+               if (strcmp(torture_type, cur_ops->name) == 0)
                        break;
-               }
        }
-       if (cur_ops == NULL) {
+       if (i == ARRAY_SIZE(torture_ops)) {
                printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
                       torture_type);
+               mutex_unlock(&fullstop_mutex);
                return (-EINVAL);
        }
-       if (cur_ops->init != NULL)
+       if (cur_ops->init)
                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 
        if (nreaders >= 0)
@@ -821,12 +1102,12 @@ rcu_torture_init(void)
        else
                nrealreaders = 2 * num_online_cpus();
        rcu_torture_print_module_parms("Start of test");
-       fullstop = 0;
+       fullstop = FULLSTOP_DONTSTOP;
 
        /* Set up the freelist. */
 
        INIT_LIST_HEAD(&rcu_torture_freelist);
-       for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
+       for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
                rcu_tortures[i].rtort_mbtest = 0;
                list_add_tail(&rcu_tortures[i].rtort_free,
                              &rcu_torture_freelist);
@@ -910,19 +1191,43 @@ rcu_torture_init(void)
        }
        if (test_no_idle_hz) {
                rcu_idle_cpu = num_online_cpus() - 1;
+
+               if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
+                       firsterr = -ENOMEM;
+                       VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
+                       goto unwind;
+               }
+
                /* Create the shuffler thread */
                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
                                          "rcu_torture_shuffle");
                if (IS_ERR(shuffler_task)) {
+                       free_cpumask_var(shuffle_tmp_mask);
                        firsterr = PTR_ERR(shuffler_task);
                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
                        shuffler_task = NULL;
                        goto unwind;
                }
        }
+       if (stutter < 0)
+               stutter = 0;
+       if (stutter) {
+               /* Create the stutter thread */
+               stutter_task = kthread_run(rcu_torture_stutter, NULL,
+                                         "rcu_torture_stutter");
+               if (IS_ERR(stutter_task)) {
+                       firsterr = PTR_ERR(stutter_task);
+                       VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
+                       stutter_task = NULL;
+                       goto unwind;
+               }
+       }
+       register_reboot_notifier(&rcutorture_nb);
+       mutex_unlock(&fullstop_mutex);
        return 0;
 
 unwind:
+       mutex_unlock(&fullstop_mutex);
        rcu_torture_cleanup();
        return firsterr;
 }