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 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update module-based scalability-test facility
  *
  * Copyright (C) IBM Corporation, 2015
  *
  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #define pr_fmt(fmt) fmt
 
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/mm.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 <uapi/linux/sched/types.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/srcu.h>
 #include <linux/slab.h>
 #include <asm/byteorder.h>
 #include <linux/torture.h>
 #include <linux/vmalloc.h>
 #include <linux/rcupdate_trace.h>
 
 #include "rcu.h"
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
 #define SCALE_FLAG "-scale:"
 #define SCALEOUT_STRING(s) \
     pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
 #define VERBOSE_SCALEOUT_STRING(s) \
     do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
 #define SCALEOUT_ERRSTRING(s) \
     pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
 
 /*
  * The intended use cases for the nreaders and nwriters module parameters
  * are as follows:
  *
  * 1.   Specify only the nr_cpus kernel boot parameter.  This will
  *  set both nreaders and nwriters to the value specified by
  *  nr_cpus for a mixed reader/writer test.
  *
  * 2.   Specify the nr_cpus kernel boot parameter, but set
  *  rcuscale.nreaders to zero.  This will set nwriters to the
  *  value specified by nr_cpus for an update-only test.
  *
  * 3.   Specify the nr_cpus kernel boot parameter, but set
  *  rcuscale.nwriters to zero.  This will set nreaders to the
  *  value specified by nr_cpus for a read-only test.
  *
  * Various other use cases may of course be specified.
  *
  * Note that this test's readers are intended only as a test load for
  * the writers.  The reader scalability statistics will be overly
  * pessimistic due to the per-critical-section interrupt disabling,
  * test-end checks, and the pair of calls through pointers.
  */
 
 #ifdef MODULE
 # define RCUSCALE_SHUTDOWN 0
 #else
 # define RCUSCALE_SHUTDOWN 1
 #endif
 
 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 torture_param(int, nwriters, -1, "Number of RCU updater threads");
 torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
           "Shutdown at end of scalability tests.");
 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
 
 static char *scale_type = "rcu";
 module_param(scale_type, charp, 0444);
 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
 
 static int nrealreaders;
 static int nrealwriters;
 static struct task_struct **writer_tasks;
 static struct task_struct **reader_tasks;
 static struct task_struct *shutdown_task;
 
 static u64 **writer_durations;
 static int *writer_n_durations;
 static atomic_t n_rcu_scale_reader_started;
 static atomic_t n_rcu_scale_writer_started;
 static atomic_t n_rcu_scale_writer_finished;
 static wait_queue_head_t shutdown_wq;
 static u64 t_rcu_scale_writer_started;
 static u64 t_rcu_scale_writer_finished;
 static unsigned long b_rcu_gp_test_started;
 static unsigned long b_rcu_gp_test_finished;
 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
 
 #define MAX_MEAS 10000
 #define MIN_MEAS 100
 
 /*
  * Operations vector for selecting different types of tests.
  */
 
 struct rcu_scale_ops {
     int ptype;
     void (*init)(void);
     void (*cleanup)(void);
     int (*readlock)(void);
     void (*readunlock)(int idx);
     unsigned long (*get_gp_seq)(void);
     unsigned long (*gp_diff)(unsigned long new, unsigned long old);
     unsigned long (*exp_completed)(void);
     void (*async)(struct rcu_head *head, rcu_callback_t func);
     void (*gp_barrier)(void);
     void (*sync)(void);
     void (*exp_sync)(void);
     const char *name;
 };
 
 static struct rcu_scale_ops *cur_ops;
 
 /*
  * Definitions for rcu scalability testing.
  */
 
 static int rcu_scale_read_lock(void) __acquires(RCU)
 {
     rcu_read_lock();
     return 0;
 }
 
 static void rcu_scale_read_unlock(int idx) __releases(RCU)
 {
     rcu_read_unlock();
 }
 
 static unsigned long __maybe_unused rcu_no_completed(void)
 {
     return 0;
 }
 
 static void rcu_sync_scale_init(void)
 {
 }
 
 static struct rcu_scale_ops rcu_ops = {
     .ptype      = RCU_FLAVOR,
     .init       = rcu_sync_scale_init,
     .readlock   = rcu_scale_read_lock,
     .readunlock = rcu_scale_read_unlock,
     .get_gp_seq = rcu_get_gp_seq,
     .gp_diff    = rcu_seq_diff,
     .exp_completed  = rcu_exp_batches_completed,
     .async      = call_rcu,
     .gp_barrier = rcu_barrier,
     .sync       = synchronize_rcu,
     .exp_sync   = synchronize_rcu_expedited,
     .name       = "rcu"
 };
 
 /*
  * Definitions for srcu scalability testing.
  */
 
 DEFINE_STATIC_SRCU(srcu_ctl_scale);
 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
 
 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
 {
     return srcu_read_lock(srcu_ctlp);
 }
 
 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
 {
     srcu_read_unlock(srcu_ctlp, idx);
 }
 
 static unsigned long srcu_scale_completed(void)
 {
     return srcu_batches_completed(srcu_ctlp);
 }
 
 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 {
     call_srcu(srcu_ctlp, head, func);
 }
 
 static void srcu_rcu_barrier(void)
 {
     srcu_barrier(srcu_ctlp);
 }
 
 static void srcu_scale_synchronize(void)
 {
     synchronize_srcu(srcu_ctlp);
 }
 
 static void srcu_scale_synchronize_expedited(void)
 {
     synchronize_srcu_expedited(srcu_ctlp);
 }
 
 static struct rcu_scale_ops srcu_ops = {
     .ptype      = SRCU_FLAVOR,
     .init       = rcu_sync_scale_init,
     .readlock   = srcu_scale_read_lock,
     .readunlock = srcu_scale_read_unlock,
     .get_gp_seq = srcu_scale_completed,
     .gp_diff    = rcu_seq_diff,
     .exp_completed  = srcu_scale_completed,
     .async      = srcu_call_rcu,
     .gp_barrier = srcu_rcu_barrier,
     .sync       = srcu_scale_synchronize,
     .exp_sync   = srcu_scale_synchronize_expedited,
     .name       = "srcu"
 };
 
 static struct srcu_struct srcud;
 
 static void srcu_sync_scale_init(void)
 {
     srcu_ctlp = &srcud;
     init_srcu_struct(srcu_ctlp);
 }
 
 static void srcu_sync_scale_cleanup(void)
 {
     cleanup_srcu_struct(srcu_ctlp);
 }
 
 static struct rcu_scale_ops srcud_ops = {
     .ptype      = SRCU_FLAVOR,
     .init       = srcu_sync_scale_init,
     .cleanup    = srcu_sync_scale_cleanup,
     .readlock   = srcu_scale_read_lock,
     .readunlock = srcu_scale_read_unlock,
     .get_gp_seq = srcu_scale_completed,
     .gp_diff    = rcu_seq_diff,
     .exp_completed  = srcu_scale_completed,
     .async      = srcu_call_rcu,
     .gp_barrier = srcu_rcu_barrier,
     .sync       = srcu_scale_synchronize,
     .exp_sync   = srcu_scale_synchronize_expedited,
     .name       = "srcud"
 };
 
 #ifdef CONFIG_TASKS_RCU
 
 /*
  * Definitions for RCU-tasks scalability testing.
  */
 
 static int tasks_scale_read_lock(void)
 {
     return 0;
 }
 
 static void tasks_scale_read_unlock(int idx)
 {
 }
 
 static struct rcu_scale_ops tasks_ops = {
     .ptype      = RCU_TASKS_FLAVOR,
     .init       = rcu_sync_scale_init,
     .readlock   = tasks_scale_read_lock,
     .readunlock = tasks_scale_read_unlock,
     .get_gp_seq = rcu_no_completed,
     .gp_diff    = rcu_seq_diff,
     .async      = call_rcu_tasks,
     .gp_barrier = rcu_barrier_tasks,
     .sync       = synchronize_rcu_tasks,
     .exp_sync   = synchronize_rcu_tasks,
     .name       = "tasks"
 };
 
 #define TASKS_OPS &tasks_ops,
 
 #else // #ifdef CONFIG_TASKS_RCU
 
 #define TASKS_OPS
 
 #endif // #else // #ifdef CONFIG_TASKS_RCU
 
 #ifdef CONFIG_TASKS_TRACE_RCU
 
 /*
  * Definitions for RCU-tasks-trace scalability testing.
  */
 
 static int tasks_trace_scale_read_lock(void)
 {
     rcu_read_lock_trace();
     return 0;
 }
 
 static void tasks_trace_scale_read_unlock(int idx)
 {
     rcu_read_unlock_trace();
 }
 
 static struct rcu_scale_ops tasks_tracing_ops = {
     .ptype      = RCU_TASKS_FLAVOR,
     .init       = rcu_sync_scale_init,
     .readlock   = tasks_trace_scale_read_lock,
     .readunlock = tasks_trace_scale_read_unlock,
     .get_gp_seq = rcu_no_completed,
     .gp_diff    = rcu_seq_diff,
     .async      = call_rcu_tasks_trace,
     .gp_barrier = rcu_barrier_tasks_trace,
     .sync       = synchronize_rcu_tasks_trace,
     .exp_sync   = synchronize_rcu_tasks_trace,
     .name       = "tasks-tracing"
 };
 
 #define TASKS_TRACING_OPS &tasks_tracing_ops,
 
 #else // #ifdef CONFIG_TASKS_TRACE_RCU
 
 #define TASKS_TRACING_OPS
 
 #endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
 
 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
 {
     if (!cur_ops->gp_diff)
         return new - old;
     return cur_ops->gp_diff(new, old);
 }
 
 /*
  * If scalability tests complete, wait for shutdown to commence.
  */
 static void rcu_scale_wait_shutdown(void)
 {
     cond_resched_tasks_rcu_qs();
     if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
         return;
     while (!torture_must_stop())
         schedule_timeout_uninterruptible(1);
 }
 
 /*
  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
  * critical section, minimizing update-side interference.  However, the
  * point of this test is not to evaluate reader scalability, but instead
  * to serve as a test load for update-side scalability testing.
  */
 static int
 rcu_scale_reader(void *arg)
 {
     unsigned long flags;
     int idx;
     long me = (long)arg;
 
     VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
     set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
     set_user_nice(current, MAX_NICE);
     atomic_inc(&n_rcu_scale_reader_started);
 
     do {
         local_irq_save(flags);
         idx = cur_ops->readlock();
         cur_ops->readunlock(idx);
         local_irq_restore(flags);
         rcu_scale_wait_shutdown();
     } while (!torture_must_stop());
     torture_kthread_stopping("rcu_scale_reader");
     return 0;
 }
 
 /*
  * Callback function for asynchronous grace periods from rcu_scale_writer().
  */
 static void rcu_scale_async_cb(struct rcu_head *rhp)
 {
     atomic_dec(this_cpu_ptr(&n_async_inflight));
     kfree(rhp);
 }
 
 /*
  * RCU scale writer kthread.  Repeatedly does a grace period.
  */
 static int
 rcu_scale_writer(void *arg)
 {
     int i = 0;
     int i_max;
     long me = (long)arg;
     struct rcu_head *rhp = NULL;
     bool started = false, done = false, alldone = false;
     u64 t;
     u64 *wdp;
     u64 *wdpp = writer_durations[me];
 
     VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
     WARN_ON(!wdpp);
     set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
     current->flags |= PF_NO_SETAFFINITY;
     sched_set_fifo_low(current);
 
     if (holdoff)
         schedule_timeout_uninterruptible(holdoff * HZ);
 
     /*
      * Wait until rcu_end_inkernel_boot() is called for normal GP tests
      * so that RCU is not always expedited for normal GP tests.
      * The system_state test is approximate, but works well in practice.
      */
     while (!gp_exp && system_state != SYSTEM_RUNNING)
         schedule_timeout_uninterruptible(1);
 
     t = ktime_get_mono_fast_ns();
     if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
         t_rcu_scale_writer_started = t;
         if (gp_exp) {
             b_rcu_gp_test_started =
                 cur_ops->exp_completed() / 2;
         } else {
             b_rcu_gp_test_started = cur_ops->get_gp_seq();
         }
     }
 
     do {
         if (writer_holdoff)
             udelay(writer_holdoff);
         wdp = &wdpp[i];
         *wdp = ktime_get_mono_fast_ns();
         if (gp_async) {
 retry:
             if (!rhp)
                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
             if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
                 atomic_inc(this_cpu_ptr(&n_async_inflight));
                 cur_ops->async(rhp, rcu_scale_async_cb);
                 rhp = NULL;
             } else if (!kthread_should_stop()) {
                 cur_ops->gp_barrier();
                 goto retry;
             } else {
                 kfree(rhp); /* Because we are stopping. */
             }
         } else if (gp_exp) {
             cur_ops->exp_sync();
         } else {
             cur_ops->sync();
         }
         t = ktime_get_mono_fast_ns();
         *wdp = t - *wdp;
         i_max = i;
         if (!started &&
             atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
             started = true;
         if (!done && i >= MIN_MEAS) {
             done = true;
             sched_set_normal(current, 0);
             pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
                  scale_type, SCALE_FLAG, me, MIN_MEAS);
             if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
                 nrealwriters) {
                 schedule_timeout_interruptible(10);
                 rcu_ftrace_dump(DUMP_ALL);
                 SCALEOUT_STRING("Test complete");
                 t_rcu_scale_writer_finished = t;
                 if (gp_exp) {
                     b_rcu_gp_test_finished =
                         cur_ops->exp_completed() / 2;
                 } else {
                     b_rcu_gp_test_finished =
                         cur_ops->get_gp_seq();
                 }
                 if (shutdown) {
                     smp_mb(); /* Assign before wake. */
                     wake_up(&shutdown_wq);
                 }
             }
         }
         if (done && !alldone &&
             atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
             alldone = true;
         if (started && !alldone && i < MAX_MEAS - 1)
             i++;
         rcu_scale_wait_shutdown();
     } while (!torture_must_stop());
     if (gp_async) {
         cur_ops->gp_barrier();
     }
     writer_n_durations[me] = i_max + 1;
     torture_kthread_stopping("rcu_scale_writer");
     return 0;
 }
 
 static void
 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 {
     pr_alert("%s" SCALE_FLAG
          "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
          scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 }
 
 static void
 rcu_scale_cleanup(void)
 {
     int i;
     int j;
     int ngps = 0;
     u64 *wdp;
     u64 *wdpp;
 
     /*
      * Would like warning at start, but everything is expedited
      * during the mid-boot phase, so have to wait till the end.
      */
     if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
         SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
     if (rcu_gp_is_normal() && gp_exp)
         SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
     if (gp_exp && gp_async)
         SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
 
     if (torture_cleanup_begin())
         return;
     if (!cur_ops) {
         torture_cleanup_end();
         return;
     }
 
     if (reader_tasks) {
         for (i = 0; i < nrealreaders; i++)
             torture_stop_kthread(rcu_scale_reader,
                          reader_tasks[i]);
         kfree(reader_tasks);
     }
 
     if (writer_tasks) {
         for (i = 0; i < nrealwriters; i++) {
             torture_stop_kthread(rcu_scale_writer,
                          writer_tasks[i]);
             if (!writer_n_durations)
                 continue;
             j = writer_n_durations[i];
             pr_alert("%s%s writer %d gps: %d\n",
                  scale_type, SCALE_FLAG, i, j);
             ngps += j;
         }
         pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
              scale_type, SCALE_FLAG,
              t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
              t_rcu_scale_writer_finished -
              t_rcu_scale_writer_started,
              ngps,
              rcuscale_seq_diff(b_rcu_gp_test_finished,
                        b_rcu_gp_test_started));
         for (i = 0; i < nrealwriters; i++) {
             if (!writer_durations)
                 break;
             if (!writer_n_durations)
                 continue;
             wdpp = writer_durations[i];
             if (!wdpp)
                 continue;
             for (j = 0; j < writer_n_durations[i]; j++) {
                 wdp = &wdpp[j];
                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
                     scale_type, SCALE_FLAG,
                     i, j, *wdp);
                 if (j % 100 == 0)
                     schedule_timeout_uninterruptible(1);
             }
             kfree(writer_durations[i]);
         }
         kfree(writer_tasks);
         kfree(writer_durations);
         kfree(writer_n_durations);
     }
 
     /* Do torture-type-specific cleanup operations.  */
     if (cur_ops->cleanup != NULL)
         cur_ops->cleanup();
 
     torture_cleanup_end();
 }
 
 /*
  * Return the number if non-negative.  If -1, the number of CPUs.
  * If less than -1, that much less than the number of CPUs, but
  * at least one.
  */
 static int compute_real(int n)
 {
     int nr;
 
     if (n >= 0) {
         nr = n;
     } else {
         nr = num_online_cpus() + 1 + n;
         if (nr <= 0)
             nr = 1;
     }
     return nr;
 }
 
 /*
  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
  * down system.
  */
 static int
 rcu_scale_shutdown(void *arg)
 {
     wait_event(shutdown_wq,
            atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
     smp_mb(); /* Wake before output. */
     rcu_scale_cleanup();
     kernel_power_off();
     return -EINVAL;
 }
 
 /*
  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
  * of iterations and measure total time and number of GP for all iterations to complete.
  */
 
 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
 torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
 torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
 
 static struct task_struct **kfree_reader_tasks;
 static int kfree_nrealthreads;
 static atomic_t n_kfree_scale_thread_started;
 static atomic_t n_kfree_scale_thread_ended;
 
 struct kfree_obj {
     char kfree_obj[8];
     struct rcu_head rh;
 };
 
 static int
 kfree_scale_thread(void *arg)
 {
     int i, loop = 0;
     long me = (long)arg;
     struct kfree_obj *alloc_ptr;
     u64 start_time, end_time;
     long long mem_begin, mem_during = 0;
     bool kfree_rcu_test_both;
     DEFINE_TORTURE_RANDOM(tr);
 
     VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
     set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
     set_user_nice(current, MAX_NICE);
     kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
 
     start_time = ktime_get_mono_fast_ns();
 
     if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
         if (gp_exp)
             b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
         else
             b_rcu_gp_test_started = cur_ops->get_gp_seq();
     }
 
     do {
         if (!mem_during) {
             mem_during = mem_begin = si_mem_available();
         } else if (loop % (kfree_loops / 4) == 0) {
             mem_during = (mem_during + si_mem_available()) / 2;
         }
 
         for (i = 0; i < kfree_alloc_num; i++) {
             alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
             if (!alloc_ptr)
                 return -ENOMEM;
 
             // By default kfree_rcu_test_single and kfree_rcu_test_double are
             // initialized to false. If both have the same value (false or true)
             // both are randomly tested, otherwise only the one with value true
             // is tested.
             if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
                     (kfree_rcu_test_both && torture_random(&tr) & 0x800))
                 kfree_rcu(alloc_ptr);
             else
                 kfree_rcu(alloc_ptr, rh);
         }
 
         cond_resched();
     } while (!torture_must_stop() && ++loop < kfree_loops);
 
     if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
         end_time = ktime_get_mono_fast_ns();
 
         if (gp_exp)
             b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
         else
             b_rcu_gp_test_finished = cur_ops->get_gp_seq();
 
         pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
                (unsigned long long)(end_time - start_time), kfree_loops,
                rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
                (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
 
         if (shutdown) {
             smp_mb(); /* Assign before wake. */
             wake_up(&shutdown_wq);
         }
     }
 
     torture_kthread_stopping("kfree_scale_thread");
     return 0;
 }
 
 static void
 kfree_scale_cleanup(void)
 {
     int i;
 
     if (torture_cleanup_begin())
         return;
 
     if (kfree_reader_tasks) {
         for (i = 0; i < kfree_nrealthreads; i++)
             torture_stop_kthread(kfree_scale_thread,
                          kfree_reader_tasks[i]);
         kfree(kfree_reader_tasks);
     }
 
     torture_cleanup_end();
 }
 
 /*
  * shutdown kthread.  Just waits to be awakened, then shuts down system.
  */
 static int
 kfree_scale_shutdown(void *arg)
 {
     wait_event(shutdown_wq,
            atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
 
     smp_mb(); /* Wake before output. */
 
     kfree_scale_cleanup();
     kernel_power_off();
     return -EINVAL;
 }
 
 static int __init
 kfree_scale_init(void)
 {
     long i;
     int firsterr = 0;
 
     kfree_nrealthreads = compute_real(kfree_nthreads);
     /* Start up the kthreads. */
     if (shutdown) {
         init_waitqueue_head(&shutdown_wq);
         firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
                           shutdown_task);
         if (torture_init_error(firsterr))
             goto unwind;
         schedule_timeout_uninterruptible(1);
     }
 
     pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 
     kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
                    GFP_KERNEL);
     if (kfree_reader_tasks == NULL) {
         firsterr = -ENOMEM;
         goto unwind;
     }
 
     for (i = 0; i < kfree_nrealthreads; i++) {
         firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
                           kfree_reader_tasks[i]);
         if (torture_init_error(firsterr))
             goto unwind;
     }
 
     while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
         schedule_timeout_uninterruptible(1);
 
     torture_init_end();
     return 0;
 
 unwind:
     torture_init_end();
     kfree_scale_cleanup();
     return firsterr;
 }
 
 static int __init
 rcu_scale_init(void)
 {
     long i;
     int firsterr = 0;
     static struct rcu_scale_ops *scale_ops[] = {
         &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_TRACING_OPS
     };
 
     if (!torture_init_begin(scale_type, verbose))
         return -EBUSY;
 
     /* Process args and announce that the scalability'er is on the job. */
     for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
         cur_ops = scale_ops[i];
         if (strcmp(scale_type, cur_ops->name) == 0)
             break;
     }
     if (i == ARRAY_SIZE(scale_ops)) {
         pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
         pr_alert("rcu-scale types:");
         for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
             pr_cont(" %s", scale_ops[i]->name);
         pr_cont("\n");
         firsterr = -EINVAL;
         cur_ops = NULL;
         goto unwind;
     }
     if (cur_ops->init)
         cur_ops->init();
 
     if (kfree_rcu_test)
         return kfree_scale_init();
 
     nrealwriters = compute_real(nwriters);
     nrealreaders = compute_real(nreaders);
     atomic_set(&n_rcu_scale_reader_started, 0);
     atomic_set(&n_rcu_scale_writer_started, 0);
     atomic_set(&n_rcu_scale_writer_finished, 0);
     rcu_scale_print_module_parms(cur_ops, "Start of test");
 
     /* Start up the kthreads. */
 
     if (shutdown) {
         init_waitqueue_head(&shutdown_wq);
         firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
                           shutdown_task);
         if (torture_init_error(firsterr))
             goto unwind;
         schedule_timeout_uninterruptible(1);
     }
     reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
                    GFP_KERNEL);
     if (reader_tasks == NULL) {
         SCALEOUT_ERRSTRING("out of memory");
         firsterr = -ENOMEM;
         goto unwind;
     }
     for (i = 0; i < nrealreaders; i++) {
         firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
                           reader_tasks[i]);
         if (torture_init_error(firsterr))
             goto unwind;
     }
     while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
         schedule_timeout_uninterruptible(1);
     writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
                    GFP_KERNEL);
     writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
                    GFP_KERNEL);
     writer_n_durations =
         kcalloc(nrealwriters, sizeof(*writer_n_durations),
             GFP_KERNEL);
     if (!writer_tasks || !writer_durations || !writer_n_durations) {
         SCALEOUT_ERRSTRING("out of memory");
         firsterr = -ENOMEM;
         goto unwind;
     }
     for (i = 0; i < nrealwriters; i++) {
         writer_durations[i] =
             kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
                 GFP_KERNEL);
         if (!writer_durations[i]) {
             firsterr = -ENOMEM;
             goto unwind;
         }
         firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
                           writer_tasks[i]);
         if (torture_init_error(firsterr))
             goto unwind;
     }
     torture_init_end();
     return 0;
 
 unwind:
     torture_init_end();
     rcu_scale_cleanup();
     if (shutdown) {
         WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
         kernel_power_off();
     }
     return firsterr;
 }
 
 module_init(rcu_scale_init);
 module_exit(rcu_scale_cleanup);

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