diff options
Diffstat (limited to 'kernel/rcutorture.c')
| -rw-r--r-- | kernel/rcutorture.c | 492 |
1 files changed, 492 insertions, 0 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c new file mode 100644 index 00000000000..9b58f1eff3c --- /dev/null +++ b/kernel/rcutorture.c @@ -0,0 +1,492 @@ +/* + * Read-Copy Update /proc-based torture test facility + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2005 + * + * Authors: Paul E. McKenney <paulmck@us.ibm.com> + * + * See also: Documentation/RCU/torture.txt + */ +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/err.h> +#include <linux/spinlock.h> +#include <linux/smp.h> +#include <linux/rcupdate.h> +#include <linux/interrupt.h> +#include <linux/sched.h> +#include <asm/atomic.h> +#include <linux/bitops.h> +#include <linux/module.h> +#include <linux/completion.h> +#include <linux/moduleparam.h> +#include <linux/percpu.h> +#include <linux/notifier.h> +#include <linux/rcuref.h> +#include <linux/cpu.h> +#include <linux/random.h> +#include <linux/delay.h> +#include <linux/byteorder/swabb.h> +#include <linux/stat.h> + +MODULE_LICENSE("GPL"); + +static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */ +static int stat_interval = 0; /* Interval between stats, in seconds. */ + /* Defaults to "only at end of test". */ +static int verbose = 0; /* Print more debug info. */ + +MODULE_PARM(nreaders, "i"); +MODULE_PARM_DESC(nreaders, "Number of RCU reader threads"); +MODULE_PARM(stat_interval, "i"); +MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s"); +MODULE_PARM(verbose, "i"); +MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s"); +#define TORTURE_FLAG "rcutorture: " +#define PRINTK_STRING(s) \ + do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0) +#define VERBOSE_PRINTK_STRING(s) \ + do { if (verbose) printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0) +#define VERBOSE_PRINTK_ERRSTRING(s) \ + do { if (verbose) printk(KERN_ALERT TORTURE_FLAG "!!! " s "\n"); } while (0) + +static char printk_buf[4096]; + +static int nrealreaders; +static struct task_struct *writer_task; +static struct task_struct **reader_tasks; +static struct task_struct *stats_task; + +#define RCU_TORTURE_PIPE_LEN 10 + +struct rcu_torture { + struct rcu_head rtort_rcu; + int rtort_pipe_count; + struct list_head rtort_free; +}; + +static int fullstop = 0; /* stop generating callbacks at test end. */ +static LIST_HEAD(rcu_torture_freelist); +static struct rcu_torture *rcu_torture_current = NULL; +static long rcu_torture_current_version = 0; +static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN]; +static DEFINE_SPINLOCK(rcu_torture_lock); +static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) = + { 0 }; +static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) = + { 0 }; +static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1]; +atomic_t n_rcu_torture_alloc; +atomic_t n_rcu_torture_alloc_fail; +atomic_t n_rcu_torture_free; + +/* + * Allocate an element from the rcu_tortures pool. + */ +struct rcu_torture * +rcu_torture_alloc(void) +{ + struct list_head *p; + + spin_lock(&rcu_torture_lock); + if (list_empty(&rcu_torture_freelist)) { + atomic_inc(&n_rcu_torture_alloc_fail); + spin_unlock(&rcu_torture_lock); + return NULL; + } + atomic_inc(&n_rcu_torture_alloc); + p = rcu_torture_freelist.next; + list_del_init(p); + spin_unlock(&rcu_torture_lock); + return container_of(p, struct rcu_torture, rtort_free); +} + +/* + * Free an element to the rcu_tortures pool. + */ +static void +rcu_torture_free(struct rcu_torture *p) +{ + atomic_inc(&n_rcu_torture_free); + spin_lock(&rcu_torture_lock); + list_add_tail(&p->rtort_free, &rcu_torture_freelist); + spin_unlock(&rcu_torture_lock); +} + +static void +rcu_torture_cb(struct rcu_head *p) +{ + int i; + struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu); + + if (fullstop) { + /* Test is ending, just drop callbacks on the floor. */ + /* The next initialization will pick up the pieces. */ + return; + } + i = rp->rtort_pipe_count; + if (i > RCU_TORTURE_PIPE_LEN) + i = RCU_TORTURE_PIPE_LEN; + atomic_inc(&rcu_torture_wcount[i]); + if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) + rcu_torture_free(rp); + else + call_rcu(p, rcu_torture_cb); +} + +struct rcu_random_state { + unsigned long rrs_state; + unsigned long rrs_count; +}; + +#define RCU_RANDOM_MULT 39916801 /* prime */ +#define RCU_RANDOM_ADD 479001701 /* prime */ +#define RCU_RANDOM_REFRESH 10000 + +#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 } + +/* + * Crude but fast random-number generator. Uses a linear congruential + * generator, with occasional help from get_random_bytes(). + */ +static long +rcu_random(struct rcu_random_state *rrsp) +{ + long refresh; + + if (--rrsp->rrs_count < 0) { + get_random_bytes(&refresh, sizeof(refresh)); + rrsp->rrs_state += refresh; + rrsp->rrs_count = RCU_RANDOM_REFRESH; + } + rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD; + return swahw32(rrsp->rrs_state); +} + +/* + * RCU torture writer kthread. Repeatedly substitutes a new structure + * for that pointed to by rcu_torture_current, freeing the old structure + * after a series of grace periods (the "pipeline"). + */ +static int +rcu_torture_writer(void *arg) +{ + int i; + long oldbatch = rcu_batches_completed(); + struct rcu_torture *rp; + struct rcu_torture *old_rp; + static DEFINE_RCU_RANDOM(rand); + + VERBOSE_PRINTK_STRING("rcu_torture_writer task started"); + do { + schedule_timeout_uninterruptible(1); + if (rcu_batches_completed() == oldbatch) + continue; + if ((rp = rcu_torture_alloc()) == NULL) + continue; + rp->rtort_pipe_count = 0; + udelay(rcu_random(&rand) & 0x3ff); + old_rp = rcu_torture_current; + rcu_assign_pointer(rcu_torture_current, rp); + smp_wmb(); + if (old_rp != NULL) { + i = old_rp->rtort_pipe_count; + if (i > RCU_TORTURE_PIPE_LEN) + i = RCU_TORTURE_PIPE_LEN; + atomic_inc(&rcu_torture_wcount[i]); + old_rp->rtort_pipe_count++; + call_rcu(&old_rp->rtort_rcu, rcu_torture_cb); + } + rcu_torture_current_version++; + oldbatch = rcu_batches_completed(); + } while (!kthread_should_stop() && !fullstop); + VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping"); + while (!kthread_should_stop()) + schedule_timeout_uninterruptible(1); + return 0; +} + +/* + * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current, + * incrementing the corresponding element of the pipeline array. The + * counter in the element should never be greater than 1, otherwise, the + * RCU implementation is broken. + */ +static int +rcu_torture_reader(void *arg) +{ + int completed; + DEFINE_RCU_RANDOM(rand); + struct rcu_torture *p; + int pipe_count; + + VERBOSE_PRINTK_STRING("rcu_torture_reader task started"); + do { + rcu_read_lock(); + completed = rcu_batches_completed(); + p = rcu_dereference(rcu_torture_current); + if (p == NULL) { + /* Wait for rcu_torture_writer to get underway */ + rcu_read_unlock(); + schedule_timeout_interruptible(HZ); + continue; + } + udelay(rcu_random(&rand) & 0x7f); + preempt_disable(); + pipe_count = p->rtort_pipe_count; + if (pipe_count > RCU_TORTURE_PIPE_LEN) { + /* Should not happen, but... */ + pipe_count = RCU_TORTURE_PIPE_LEN; + } + ++__get_cpu_var(rcu_torture_count)[pipe_count]; + completed = rcu_batches_completed() - completed; + if (completed > RCU_TORTURE_PIPE_LEN) { + /* Should not happen, but... */ + completed = RCU_TORTURE_PIPE_LEN; + } + ++__get_cpu_var(rcu_torture_batch)[completed]; + preempt_enable(); + rcu_read_unlock(); + schedule(); + } while (!kthread_should_stop() && !fullstop); + VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping"); + while (!kthread_should_stop()) + schedule_timeout_uninterruptible(1); + return 0; +} + +/* + * Create an RCU-torture statistics message in the specified buffer. + */ +static int +rcu_torture_printk(char *page) +{ + int cnt = 0; + int cpu; + int i; + long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; + long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; + + for_each_cpu(cpu) { + for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { + pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i]; + batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i]; + } + } + for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) { + if (pipesummary[i] != 0) + break; + } + cnt += sprintf(&page[cnt], "rcutorture: "); + cnt += sprintf(&page[cnt], + "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d", + rcu_torture_current, + rcu_torture_current_version, + list_empty(&rcu_torture_freelist), + atomic_read(&n_rcu_torture_alloc), + atomic_read(&n_rcu_torture_alloc_fail), + atomic_read(&n_rcu_torture_free)); + cnt += sprintf(&page[cnt], "\nrcutorture: "); + if (i > 1) + cnt += sprintf(&page[cnt], "!!! "); + cnt += sprintf(&page[cnt], "Reader Pipe: "); + for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) + cnt += sprintf(&page[cnt], " %ld", pipesummary[i]); + cnt += sprintf(&page[cnt], "\nrcutorture: "); + cnt += sprintf(&page[cnt], "Reader Batch: "); + for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++) + cnt += sprintf(&page[cnt], " %ld", batchsummary[i]); + cnt += sprintf(&page[cnt], "\nrcutorture: "); + cnt += sprintf(&page[cnt], "Free-Block Circulation: "); + for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { + cnt += sprintf(&page[cnt], " %d", + atomic_read(&rcu_torture_wcount[i])); + } + cnt += sprintf(&page[cnt], "\n"); + return cnt; +} + +/* + * Print torture statistics. Caller must ensure that there is only + * one call to this function at a given time!!! This is normally + * accomplished by relying on the module system to only have one copy + * of the module loaded, and then by giving the rcu_torture_stats + * kthread full control (or the init/cleanup functions when rcu_torture_stats + * thread is not running). + */ +static void +rcu_torture_stats_print(void) +{ + int cnt; + + cnt = rcu_torture_printk(printk_buf); + printk(KERN_ALERT "%s", printk_buf); +} + +/* + * Periodically prints torture statistics, if periodic statistics printing + * was specified via the stat_interval module parameter. + * + * No need to worry about fullstop here, since this one doesn't reference + * volatile state or register callbacks. + */ +static int +rcu_torture_stats(void *arg) +{ + VERBOSE_PRINTK_STRING("rcu_torture_stats task started"); + do { + schedule_timeout_interruptible(stat_interval * HZ); + rcu_torture_stats_print(); + } while (!kthread_should_stop()); + VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping"); + return 0; +} + +static void +rcu_torture_cleanup(void) +{ + int i; + + fullstop = 1; + if (writer_task != NULL) { + VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task"); + kthread_stop(writer_task); + } + writer_task = NULL; + + if (reader_tasks != NULL) { + for (i = 0; i < nrealreaders; i++) { + if (reader_tasks[i] != NULL) { + VERBOSE_PRINTK_STRING( + "Stopping rcu_torture_reader task"); + kthread_stop(reader_tasks[i]); + } + reader_tasks[i] = NULL; + } + kfree(reader_tasks); + reader_tasks = NULL; + } + rcu_torture_current = NULL; + + if (stats_task != NULL) { + VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task"); + kthread_stop(stats_task); + } + stats_task = NULL; + + /* Wait for all RCU callbacks to fire. */ + + for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++) + synchronize_rcu(); + rcu_torture_stats_print(); /* -After- the stats thread is stopped! */ + PRINTK_STRING("--- End of test"); +} + +static int +rcu_torture_init(void) +{ + int i; + int cpu; + int firsterr = 0; + + /* Process args and tell the world that the torturer is on the job. */ + + if (nreaders >= 0) + nrealreaders = nreaders; + else + nrealreaders = 2 * num_online_cpus(); + printk(KERN_ALERT TORTURE_FLAG + "--- Start of test: nreaders=%d stat_interval=%d verbose=%d\n", + nrealreaders, stat_interval, verbose); + fullstop = 0; + + /* Set up the freelist. */ + + INIT_LIST_HEAD(&rcu_torture_freelist); + for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) { + list_add_tail(&rcu_tortures[i].rtort_free, + &rcu_torture_freelist); + } + + /* Initialize the statistics so that each run gets its own numbers. */ + + rcu_torture_current = NULL; + rcu_torture_current_version = 0; + atomic_set(&n_rcu_torture_alloc, 0); + atomic_set(&n_rcu_torture_alloc_fail, 0); + atomic_set(&n_rcu_torture_free, 0); + for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) + atomic_set(&rcu_torture_wcount[i], 0); + for_each_cpu(cpu) { + for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { + per_cpu(rcu_torture_count, cpu)[i] = 0; + per_cpu(rcu_torture_batch, cpu)[i] = 0; + } + } + + /* Start up the kthreads. */ + + VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task"); + writer_task = kthread_run(rcu_torture_writer, NULL, + "rcu_torture_writer"); + if (IS_ERR(writer_task)) { + firsterr = PTR_ERR(writer_task); + VERBOSE_PRINTK_ERRSTRING("Failed to create writer"); + writer_task = NULL; + goto unwind; + } + reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]), + GFP_KERNEL); + if (reader_tasks == NULL) { + VERBOSE_PRINTK_ERRSTRING("out of memory"); + firsterr = -ENOMEM; + goto unwind; + } + for (i = 0; i < nrealreaders; i++) { + VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task"); + reader_tasks[i] = kthread_run(rcu_torture_reader, NULL, + "rcu_torture_reader"); + if (IS_ERR(reader_tasks[i])) { + firsterr = PTR_ERR(reader_tasks[i]); + VERBOSE_PRINTK_ERRSTRING("Failed to create reader"); + reader_tasks[i] = NULL; + goto unwind; + } + } + if (stat_interval > 0) { + VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task"); + stats_task = kthread_run(rcu_torture_stats, NULL, + "rcu_torture_stats"); + if (IS_ERR(stats_task)) { + firsterr = PTR_ERR(stats_task); + VERBOSE_PRINTK_ERRSTRING("Failed to create stats"); + stats_task = NULL; + goto unwind; + } + } + return 0; + +unwind: + rcu_torture_cleanup(); + return firsterr; +} + +module_init(rcu_torture_init); +module_exit(rcu_torture_cleanup); |