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![Ingo Molnar](/assets/img/avatar_default.png)
rcu_torture_lock is used in a softirq-unsafe manner, but it is also taken by rcu_torture_cb(), which may execute in softirq-context, resulting in potential deadlocks. The fix is to acquire rcu_torture_lock in a softirq-safe manner. With this fix applied, the rcu-torture code passes validation. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Paul E. McKenney <paulmck@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
598 lines
17 KiB
C
598 lines
17 KiB
C
/*
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* Read-Copy Update /proc-based torture test facility
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2005
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*
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* Authors: Paul E. McKenney <paulmck@us.ibm.com>
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*
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* See also: Documentation/RCU/torture.txt
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/err.h>
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/rcupdate.h>
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#include <linux/interrupt.h>
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#include <linux/sched.h>
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#include <asm/atomic.h>
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#include <linux/bitops.h>
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#include <linux/module.h>
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#include <linux/completion.h>
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#include <linux/moduleparam.h>
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#include <linux/percpu.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/random.h>
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#include <linux/delay.h>
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#include <linux/byteorder/swabb.h>
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#include <linux/stat.h>
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MODULE_LICENSE("GPL");
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static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */
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static int stat_interval; /* Interval between stats, in seconds. */
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/* Defaults to "only at end of test". */
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static int verbose; /* Print more debug info. */
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static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
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static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
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MODULE_PARM(nreaders, "i");
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MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
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MODULE_PARM(stat_interval, "i");
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MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
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MODULE_PARM(verbose, "i");
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MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
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MODULE_PARM(test_no_idle_hz, "i");
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MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
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MODULE_PARM(shuffle_interval, "i");
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MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
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#define TORTURE_FLAG "rcutorture: "
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#define PRINTK_STRING(s) \
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do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
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#define VERBOSE_PRINTK_STRING(s) \
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do { if (verbose) printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
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#define VERBOSE_PRINTK_ERRSTRING(s) \
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do { if (verbose) printk(KERN_ALERT TORTURE_FLAG "!!! " s "\n"); } while (0)
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static char printk_buf[4096];
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static int nrealreaders;
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static struct task_struct *writer_task;
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static struct task_struct **reader_tasks;
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static struct task_struct *stats_task;
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static struct task_struct *shuffler_task;
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#define RCU_TORTURE_PIPE_LEN 10
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struct rcu_torture {
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struct rcu_head rtort_rcu;
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int rtort_pipe_count;
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struct list_head rtort_free;
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int rtort_mbtest;
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};
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static int fullstop = 0; /* stop generating callbacks at test end. */
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static LIST_HEAD(rcu_torture_freelist);
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static struct rcu_torture *rcu_torture_current = NULL;
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static long rcu_torture_current_version = 0;
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static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
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static DEFINE_SPINLOCK(rcu_torture_lock);
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static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
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{ 0 };
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static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
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{ 0 };
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static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
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atomic_t n_rcu_torture_alloc;
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atomic_t n_rcu_torture_alloc_fail;
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atomic_t n_rcu_torture_free;
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atomic_t n_rcu_torture_mberror;
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atomic_t n_rcu_torture_error;
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/*
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* Allocate an element from the rcu_tortures pool.
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*/
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static struct rcu_torture *
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rcu_torture_alloc(void)
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{
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struct list_head *p;
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spin_lock_bh(&rcu_torture_lock);
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if (list_empty(&rcu_torture_freelist)) {
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atomic_inc(&n_rcu_torture_alloc_fail);
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spin_unlock_bh(&rcu_torture_lock);
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return NULL;
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}
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atomic_inc(&n_rcu_torture_alloc);
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p = rcu_torture_freelist.next;
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list_del_init(p);
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spin_unlock_bh(&rcu_torture_lock);
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return container_of(p, struct rcu_torture, rtort_free);
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}
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/*
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* Free an element to the rcu_tortures pool.
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*/
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static void
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rcu_torture_free(struct rcu_torture *p)
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{
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atomic_inc(&n_rcu_torture_free);
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spin_lock_bh(&rcu_torture_lock);
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list_add_tail(&p->rtort_free, &rcu_torture_freelist);
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spin_unlock_bh(&rcu_torture_lock);
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}
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static void
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rcu_torture_cb(struct rcu_head *p)
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{
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int i;
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struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
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if (fullstop) {
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/* Test is ending, just drop callbacks on the floor. */
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/* The next initialization will pick up the pieces. */
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return;
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}
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i = rp->rtort_pipe_count;
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if (i > RCU_TORTURE_PIPE_LEN)
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i = RCU_TORTURE_PIPE_LEN;
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atomic_inc(&rcu_torture_wcount[i]);
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if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
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rp->rtort_mbtest = 0;
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rcu_torture_free(rp);
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} else
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call_rcu(p, rcu_torture_cb);
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}
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struct rcu_random_state {
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unsigned long rrs_state;
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unsigned long rrs_count;
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};
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#define RCU_RANDOM_MULT 39916801 /* prime */
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#define RCU_RANDOM_ADD 479001701 /* prime */
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#define RCU_RANDOM_REFRESH 10000
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#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
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/*
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* Crude but fast random-number generator. Uses a linear congruential
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* generator, with occasional help from get_random_bytes().
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*/
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static long
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rcu_random(struct rcu_random_state *rrsp)
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{
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long refresh;
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if (--rrsp->rrs_count < 0) {
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get_random_bytes(&refresh, sizeof(refresh));
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rrsp->rrs_state += refresh;
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rrsp->rrs_count = RCU_RANDOM_REFRESH;
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}
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rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
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return swahw32(rrsp->rrs_state);
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}
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/*
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* RCU torture writer kthread. Repeatedly substitutes a new structure
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* for that pointed to by rcu_torture_current, freeing the old structure
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* after a series of grace periods (the "pipeline").
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*/
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static int
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rcu_torture_writer(void *arg)
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{
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int i;
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long oldbatch = rcu_batches_completed();
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struct rcu_torture *rp;
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struct rcu_torture *old_rp;
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static DEFINE_RCU_RANDOM(rand);
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VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
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set_user_nice(current, 19);
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do {
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schedule_timeout_uninterruptible(1);
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if (rcu_batches_completed() == oldbatch)
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continue;
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if ((rp = rcu_torture_alloc()) == NULL)
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continue;
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rp->rtort_pipe_count = 0;
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udelay(rcu_random(&rand) & 0x3ff);
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old_rp = rcu_torture_current;
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rp->rtort_mbtest = 1;
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rcu_assign_pointer(rcu_torture_current, rp);
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smp_wmb();
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if (old_rp != NULL) {
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i = old_rp->rtort_pipe_count;
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if (i > RCU_TORTURE_PIPE_LEN)
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i = RCU_TORTURE_PIPE_LEN;
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atomic_inc(&rcu_torture_wcount[i]);
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old_rp->rtort_pipe_count++;
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call_rcu(&old_rp->rtort_rcu, rcu_torture_cb);
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}
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rcu_torture_current_version++;
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oldbatch = rcu_batches_completed();
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} while (!kthread_should_stop() && !fullstop);
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VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
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while (!kthread_should_stop())
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schedule_timeout_uninterruptible(1);
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return 0;
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}
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/*
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* RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
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* incrementing the corresponding element of the pipeline array. The
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* counter in the element should never be greater than 1, otherwise, the
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* RCU implementation is broken.
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*/
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static int
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rcu_torture_reader(void *arg)
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{
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int completed;
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DEFINE_RCU_RANDOM(rand);
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struct rcu_torture *p;
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int pipe_count;
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VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
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set_user_nice(current, 19);
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do {
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rcu_read_lock();
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completed = rcu_batches_completed();
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p = rcu_dereference(rcu_torture_current);
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if (p == NULL) {
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/* Wait for rcu_torture_writer to get underway */
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rcu_read_unlock();
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schedule_timeout_interruptible(HZ);
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continue;
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}
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if (p->rtort_mbtest == 0)
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atomic_inc(&n_rcu_torture_mberror);
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udelay(rcu_random(&rand) & 0x7f);
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preempt_disable();
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pipe_count = p->rtort_pipe_count;
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if (pipe_count > RCU_TORTURE_PIPE_LEN) {
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/* Should not happen, but... */
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pipe_count = RCU_TORTURE_PIPE_LEN;
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}
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++__get_cpu_var(rcu_torture_count)[pipe_count];
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completed = rcu_batches_completed() - completed;
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if (completed > RCU_TORTURE_PIPE_LEN) {
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/* Should not happen, but... */
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completed = RCU_TORTURE_PIPE_LEN;
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}
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++__get_cpu_var(rcu_torture_batch)[completed];
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preempt_enable();
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rcu_read_unlock();
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schedule();
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} while (!kthread_should_stop() && !fullstop);
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VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
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while (!kthread_should_stop())
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schedule_timeout_uninterruptible(1);
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return 0;
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}
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/*
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* Create an RCU-torture statistics message in the specified buffer.
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*/
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static int
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rcu_torture_printk(char *page)
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{
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int cnt = 0;
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int cpu;
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int i;
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long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
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long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
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for_each_cpu(cpu) {
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for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
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pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
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batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
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}
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}
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for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
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if (pipesummary[i] != 0)
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break;
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}
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cnt += sprintf(&page[cnt], "rcutorture: ");
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cnt += sprintf(&page[cnt],
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"rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
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"rtmbe: %d",
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rcu_torture_current,
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rcu_torture_current_version,
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list_empty(&rcu_torture_freelist),
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atomic_read(&n_rcu_torture_alloc),
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atomic_read(&n_rcu_torture_alloc_fail),
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atomic_read(&n_rcu_torture_free),
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atomic_read(&n_rcu_torture_mberror));
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if (atomic_read(&n_rcu_torture_mberror) != 0)
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cnt += sprintf(&page[cnt], " !!!");
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cnt += sprintf(&page[cnt], "\nrcutorture: ");
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if (i > 1) {
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cnt += sprintf(&page[cnt], "!!! ");
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atomic_inc(&n_rcu_torture_error);
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}
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cnt += sprintf(&page[cnt], "Reader Pipe: ");
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for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
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cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
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cnt += sprintf(&page[cnt], "\nrcutorture: ");
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cnt += sprintf(&page[cnt], "Reader Batch: ");
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for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++)
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cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
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cnt += sprintf(&page[cnt], "\nrcutorture: ");
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cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
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for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
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cnt += sprintf(&page[cnt], " %d",
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atomic_read(&rcu_torture_wcount[i]));
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}
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cnt += sprintf(&page[cnt], "\n");
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return cnt;
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}
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/*
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* Print torture statistics. Caller must ensure that there is only
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* one call to this function at a given time!!! This is normally
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* accomplished by relying on the module system to only have one copy
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* of the module loaded, and then by giving the rcu_torture_stats
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* kthread full control (or the init/cleanup functions when rcu_torture_stats
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* thread is not running).
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*/
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static void
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rcu_torture_stats_print(void)
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{
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int cnt;
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cnt = rcu_torture_printk(printk_buf);
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printk(KERN_ALERT "%s", printk_buf);
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}
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/*
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* Periodically prints torture statistics, if periodic statistics printing
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* was specified via the stat_interval module parameter.
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*
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* No need to worry about fullstop here, since this one doesn't reference
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* volatile state or register callbacks.
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*/
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static int
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rcu_torture_stats(void *arg)
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{
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VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
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do {
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schedule_timeout_interruptible(stat_interval * HZ);
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rcu_torture_stats_print();
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} while (!kthread_should_stop());
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VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
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return 0;
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}
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static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
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/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
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* is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
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*/
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void rcu_torture_shuffle_tasks(void)
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{
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cpumask_t tmp_mask = CPU_MASK_ALL;
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int i;
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lock_cpu_hotplug();
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/* No point in shuffling if there is only one online CPU (ex: UP) */
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if (num_online_cpus() == 1) {
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unlock_cpu_hotplug();
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return;
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}
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if (rcu_idle_cpu != -1)
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cpu_clear(rcu_idle_cpu, tmp_mask);
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set_cpus_allowed(current, tmp_mask);
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if (reader_tasks != NULL) {
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for (i = 0; i < nrealreaders; i++)
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if (reader_tasks[i])
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set_cpus_allowed(reader_tasks[i], tmp_mask);
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}
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if (writer_task)
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set_cpus_allowed(writer_task, tmp_mask);
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if (stats_task)
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set_cpus_allowed(stats_task, tmp_mask);
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if (rcu_idle_cpu == -1)
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rcu_idle_cpu = num_online_cpus() - 1;
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else
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rcu_idle_cpu--;
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unlock_cpu_hotplug();
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}
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/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
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* system to become idle at a time and cut off its timer ticks. This is meant
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* to test the support for such tickless idle CPU in RCU.
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*/
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static int
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rcu_torture_shuffle(void *arg)
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{
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VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
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do {
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schedule_timeout_interruptible(shuffle_interval * HZ);
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rcu_torture_shuffle_tasks();
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} while (!kthread_should_stop());
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VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
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return 0;
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}
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static void
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rcu_torture_cleanup(void)
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{
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int i;
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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! */
|
|
printk(KERN_ALERT TORTURE_FLAG
|
|
"--- End of test: %s\n",
|
|
atomic_read(&n_rcu_torture_error) == 0 ? "SUCCESS" : "FAILURE");
|
|
}
|
|
|
|
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 test_no_idle_hz=%d "
|
|
"shuffle_interval = %d\n",
|
|
nrealreaders, stat_interval, verbose, test_no_idle_hz,
|
|
shuffle_interval);
|
|
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_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);
|