| /* |
| * 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); |