/* * Common functions for in-kernel torture tests. * * 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, you can access it online at * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (C) IBM Corporation, 2014 * * Author: Paul E. McKenney * Based on kernel/rcu/torture.c. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney "); int fullstop = FULLSTOP_RMMOD; EXPORT_SYMBOL_GPL(fullstop); DEFINE_MUTEX(fullstop_mutex); EXPORT_SYMBOL_GPL(fullstop_mutex); #define TORTURE_RANDOM_MULT 39916801 /* prime */ #define TORTURE_RANDOM_ADD 479001701 /* prime */ #define TORTURE_RANDOM_REFRESH 10000 /* * Crude but fast random-number generator. Uses a linear congruential * generator, with occasional help from cpu_clock(). */ unsigned long torture_random(struct torture_random_state *trsp) { if (--trsp->trs_count < 0) { trsp->trs_state += (unsigned long)local_clock(); trsp->trs_count = TORTURE_RANDOM_REFRESH; } trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT + TORTURE_RANDOM_ADD; return swahw32(trsp->trs_state); } EXPORT_SYMBOL_GPL(torture_random); /* * Variables for shuffling. The idea is to ensure that each CPU stays * idle for an extended period to test interactions with dyntick idle, * as well as interactions with any per-CPU varibles. */ struct shuffle_task { struct list_head st_l; struct task_struct *st_t; }; static long shuffle_interval; /* In jiffies. */ static struct task_struct *shuffler_task; static cpumask_var_t shuffle_tmp_mask; static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */ static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list); static DEFINE_MUTEX(shuffle_task_mutex); /* * Register a task to be shuffled. If there is no memory, just splat * and don't bother registering. */ void torture_shuffle_task_register(struct task_struct *tp) { struct shuffle_task *stp; if (WARN_ON_ONCE(tp == NULL)) return; stp = kmalloc(sizeof(*stp), GFP_KERNEL); if (WARN_ON_ONCE(stp == NULL)) return; stp->st_t = tp; mutex_lock(&shuffle_task_mutex); list_add(&stp->st_l, &shuffle_task_list); mutex_unlock(&shuffle_task_mutex); } EXPORT_SYMBOL_GPL(torture_shuffle_task_register); /* * Unregister all tasks, for example, at the end of the torture run. */ static void torture_shuffle_task_unregister_all(void) { struct shuffle_task *stp; struct shuffle_task *p; mutex_lock(&shuffle_task_mutex); list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) { list_del(&stp->st_l); kfree(stp); } mutex_unlock(&shuffle_task_mutex); } /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle. * A special case is when shuffle_idle_cpu = -1, in which case we allow * the tasks to run on all CPUs. */ static void torture_shuffle_tasks(void) { struct shuffle_task *stp; cpumask_setall(shuffle_tmp_mask); get_online_cpus(); /* No point in shuffling if there is only one online CPU (ex: UP) */ if (num_online_cpus() == 1) { put_online_cpus(); return; } /* Advance to the next CPU. Upon overflow, don't idle any CPUs. */ shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask); if (shuffle_idle_cpu >= nr_cpu_ids) shuffle_idle_cpu = -1; if (shuffle_idle_cpu != -1) { cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask); if (cpumask_empty(shuffle_tmp_mask)) { put_online_cpus(); return; } } mutex_lock(&shuffle_task_mutex); list_for_each_entry(stp, &shuffle_task_list, st_l) set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask); mutex_unlock(&shuffle_task_mutex); put_online_cpus(); } /* 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 torture_shuffle(void *arg) { VERBOSE_TOROUT_STRING("torture_shuffle task started"); do { schedule_timeout_interruptible(shuffle_interval); torture_shuffle_tasks(); torture_shutdown_absorb("torture_shuffle"); } while (!torture_must_stop()); VERBOSE_TOROUT_STRING("torture_shuffle task stopping"); return 0; } /* * Start the shuffler, with shuffint in jiffies. */ int torture_shuffle_init(long shuffint) { int ret; shuffle_interval = shuffint; shuffle_idle_cpu = -1; if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) { VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask"); return -ENOMEM; } /* Create the shuffler thread */ shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle"); if (IS_ERR(shuffler_task)) { ret = PTR_ERR(shuffler_task); free_cpumask_var(shuffle_tmp_mask); VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler"); shuffler_task = NULL; return ret; } torture_shuffle_task_register(shuffler_task); return 0; } EXPORT_SYMBOL_GPL(torture_shuffle_init); /* * Stop the shuffling. */ void torture_shuffle_cleanup(void) { torture_shuffle_task_unregister_all(); if (shuffler_task) { VERBOSE_TOROUT_STRING("Stopping torture_shuffle task"); kthread_stop(shuffler_task); free_cpumask_var(shuffle_tmp_mask); } shuffler_task = NULL; } EXPORT_SYMBOL_GPL(torture_shuffle_cleanup); /* * Absorb kthreads into a kernel function that won't return, so that * they won't ever access module text or data again. */ void torture_shutdown_absorb(const char *title) { while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) { pr_notice( "torture thread %s parking due to system shutdown\n", title); schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT); } } EXPORT_SYMBOL_GPL(torture_shutdown_absorb);