/* * 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);