// SPDX-License-Identifier: GPL-2.0+ // // Torture test for smp_call_function() and friends. // // Copyright (C) Facebook, 2020. // // Author: Paul E. McKenney <paulmck@kernel.org> #define pr_fmt(fmt) fmt #include <linux/atomic.h> #include <linux/bitops.h> #include <linux/completion.h> #include <linux/cpu.h> #include <linux/delay.h> #include <linux/err.h> #include <linux/init.h> #include <linux/interrupt.h> #include <linux/kthread.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/notifier.h> #include <linux/percpu.h> #include <linux/rcupdate.h> #include <linux/rcupdate_trace.h> #include <linux/reboot.h> #include <linux/sched.h> #include <linux/spinlock.h> #include <linux/smp.h> #include <linux/stat.h> #include <linux/srcu.h> #include <linux/slab.h> #include <linux/torture.h> #include <linux/types.h> #define SCFTORT_STRING "scftorture" #define SCFTORT_FLAG SCFTORT_STRING ": " #define VERBOSE_SCFTORTOUT(s, x...) \ do { if (verbose) pr_alert(SCFTORT_FLAG s "\n", ## x); } while (0) #define SCFTORTOUT_ERRSTRING(s, x...) pr_alert(SCFTORT_FLAG "!!! " s "\n", ## x) MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>"); // Wait until there are multiple CPUs before starting test. torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0, "Holdoff time before test start (s)"); torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)"); torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs."); torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)"); torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable"); torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable."); torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s."); torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable"); torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug."); torture_param(int, verbose, 0, "Enable verbose debugging printk()s"); torture_param(int, weight_resched, -1, "Testing weight for resched_cpu() operations."); torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations."); torture_param(int, weight_single_rpc, -1, "Testing weight for single-CPU RPC operations."); torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations."); torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations."); torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations."); torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations."); torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations."); char *torture_type = ""; #ifdef MODULE # define SCFTORT_SHUTDOWN 0 #else # define SCFTORT_SHUTDOWN 1 #endif torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test."); struct scf_statistics { struct task_struct *task; int cpu; long long n_resched; long long n_single; long long n_single_ofl; long long n_single_rpc; long long n_single_rpc_ofl; long long n_single_wait; long long n_single_wait_ofl; long long n_many; long long n_many_wait; long long n_all; long long n_all_wait; }; static struct scf_statistics *scf_stats_p; static struct task_struct *scf_torture_stats_task; static DEFINE_PER_CPU(long long, scf_invoked_count); // Data for random primitive selection #define SCF_PRIM_RESCHED 0 #define SCF_PRIM_SINGLE 1 #define SCF_PRIM_SINGLE_RPC 2 #define SCF_PRIM_MANY 3 #define SCF_PRIM_ALL 4 #define SCF_NPRIMS 8 // Need wait and no-wait versions of each, // except for SCF_PRIM_RESCHED and // SCF_PRIM_SINGLE_RPC. static char *scf_prim_name[] = { "resched_cpu", "smp_call_function_single", "smp_call_function_single_rpc", "smp_call_function_many", "smp_call_function", }; struct scf_selector { unsigned long scfs_weight; int scfs_prim; bool scfs_wait; }; static struct scf_selector scf_sel_array[SCF_NPRIMS]; static int scf_sel_array_len; static unsigned long scf_sel_totweight; // Communicate between caller and handler. struct scf_check { bool scfc_in; bool scfc_out; int scfc_cpu; // -1 for not _single(). bool scfc_wait; bool scfc_rpc; struct completion scfc_completion; }; // Use to wait for all threads to start. static atomic_t n_started; static atomic_t n_errs; static atomic_t n_mb_in_errs; static atomic_t n_mb_out_errs; static atomic_t n_alloc_errs; static bool scfdone; static char *bangstr = ""; static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand); extern void resched_cpu(int cpu); // An alternative IPI vector. // Print torture statistics. Caller must ensure serialization. static void scf_torture_stats_print(void) { int cpu; int i; long long invoked_count = 0; bool isdone = READ_ONCE(scfdone); struct scf_statistics scfs = {}; for_each_possible_cpu(cpu) invoked_count += data_race(per_cpu(scf_invoked_count, cpu)); for (i = 0; i < nthreads; i++) { scfs.n_resched += scf_stats_p[i].n_resched; scfs.n_single += scf_stats_p[i].n_single; scfs.n_single_ofl += scf_stats_p[i].n_single_ofl; scfs.n_single_rpc += scf_stats_p[i].n_single_rpc; scfs.n_single_wait += scf_stats_p[i].n_single_wait; scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl; scfs.n_many += scf_stats_p[i].n_many; scfs.n_many_wait += scf_stats_p[i].n_many_wait; scfs.n_all += scf_stats_p[i].n_all; scfs.n_all_wait += scf_stats_p[i].n_all_wait; } if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs)) bangstr = "!!! "; pr_alert("%s %sscf_invoked_count %s: %lld resched: %lld single: %lld/%lld single_ofl: %lld/%lld single_rpc: %lld single_rpc_ofl: %lld many: %lld/%lld all: %lld/%lld ", SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count, scfs.n_resched, scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl, scfs.n_single_rpc, scfs.n_single_rpc_ofl, scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait); torture_onoff_stats(); pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs), atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs), atomic_read(&n_alloc_errs)); } // Periodically prints torture statistics, if periodic statistics printing // was specified via the stat_interval module parameter. static int scf_torture_stats(void *arg) { VERBOSE_TOROUT_STRING("scf_torture_stats task started"); do { schedule_timeout_interruptible(stat_interval * HZ); scf_torture_stats_print(); torture_shutdown_absorb("scf_torture_stats"); } while (!torture_must_stop()); torture_kthread_stopping("scf_torture_stats"); return 0; } // Add a primitive to the scf_sel_array[]. static void scf_sel_add(unsigned long weight, int prim, bool wait) { struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len]; // If no weight, if array would overflow, if computing three-place // percentages would overflow, or if the scf_prim_name[] array would // overflow, don't bother. In the last three two cases, complain. if (!weight || WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) || WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) || WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name))) return; scf_sel_totweight += weight; scfsp->scfs_weight = scf_sel_totweight; scfsp->scfs_prim = prim; scfsp->scfs_wait = wait; scf_sel_array_len++; } // Dump out weighting percentages for scf_prim_name[] array. static void scf_sel_dump(void) { int i; unsigned long oldw = 0; struct scf_selector *scfsp; unsigned long w; for (i = 0; i < scf_sel_array_len; i++) { scfsp = &scf_sel_array[i]; w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight; pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000, scf_prim_name[scfsp->scfs_prim], scfsp->scfs_wait ? "wait" : "nowait"); oldw = scfsp->scfs_weight; } } // Randomly pick a primitive and wait/nowait, based on weightings. static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp) { int i; unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1); for (i = 0; i < scf_sel_array_len; i++) if (scf_sel_array[i].scfs_weight >= w) return &scf_sel_array[i]; WARN_ON_ONCE(1); return &scf_sel_array[0]; } // Update statistics and occasionally burn up mass quantities of CPU time, // if told to do so via scftorture.longwait. Otherwise, occasionally burn // a little bit. static void scf_handler(void *scfc_in) { int i; int j; unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand)); struct scf_check *scfcp = scfc_in; if (likely(scfcp)) { WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers. if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in)))) atomic_inc(&n_mb_in_errs); } this_cpu_inc(scf_invoked_count); if (longwait <= 0) { if (!(r & 0xffc0)) { udelay(r & 0x3f); goto out; } } if (r & 0xfff) goto out; r = (r >> 12); if (longwait <= 0) { udelay((r & 0xff) + 1); goto out; } r = r % longwait + 1; for (i = 0; i < r; i++) { for (j = 0; j < 1000; j++) { udelay(1000); cpu_relax(); } } out: if (unlikely(!scfcp)) return; if (scfcp->scfc_wait) { WRITE_ONCE(scfcp->scfc_out, true); if (scfcp->scfc_rpc) complete(&scfcp->scfc_completion); } else { kfree(scfcp); } } // As above, but check for correct CPU. static void scf_handler_1(void *scfc_in) { struct scf_check *scfcp = scfc_in; if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) { atomic_inc(&n_errs); } scf_handler(scfcp); } // Randomly do an smp_call_function*() invocation. static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp) { uintptr_t cpu; int ret = 0; struct scf_check *scfcp = NULL; struct scf_selector *scfsp = scf_sel_rand(trsp); if (use_cpus_read_lock) cpus_read_lock(); else preempt_disable(); if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) { scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); if (WARN_ON_ONCE(!scfcp)) { atomic_inc(&n_alloc_errs); } else { scfcp->scfc_cpu = -1; scfcp->scfc_wait = scfsp->scfs_wait; scfcp->scfc_out = false; scfcp->scfc_rpc = false; } } switch (scfsp->scfs_prim) { case SCF_PRIM_RESCHED: if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) { cpu = torture_random(trsp) % nr_cpu_ids; scfp->n_resched++; resched_cpu(cpu); this_cpu_inc(scf_invoked_count); } break; case SCF_PRIM_SINGLE: cpu = torture_random(trsp) % nr_cpu_ids; if (scfsp->scfs_wait) scfp->n_single_wait++; else scfp->n_single++; if (scfcp) { scfcp->scfc_cpu = cpu; barrier(); // Prevent race-reduction compiler optimizations. scfcp->scfc_in = true; } ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait); if (ret) { if (scfsp->scfs_wait) scfp->n_single_wait_ofl++; else scfp->n_single_ofl++; kfree(scfcp); scfcp = NULL; } break; case SCF_PRIM_SINGLE_RPC: if (!scfcp) break; cpu = torture_random(trsp) % nr_cpu_ids; scfp->n_single_rpc++; scfcp->scfc_cpu = cpu; scfcp->scfc_wait = true; init_completion(&scfcp->scfc_completion); scfcp->scfc_rpc = true; barrier(); // Prevent race-reduction compiler optimizations. scfcp->scfc_in = true; ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, 0); if (!ret) { if (use_cpus_read_lock) cpus_read_unlock(); else preempt_enable(); wait_for_completion(&scfcp->scfc_completion); if (use_cpus_read_lock) cpus_read_lock(); else preempt_disable(); } else { scfp->n_single_rpc_ofl++; kfree(scfcp); scfcp = NULL; } break; case SCF_PRIM_MANY: if (scfsp->scfs_wait) scfp->n_many_wait++; else scfp->n_many++; if (scfcp) { barrier(); // Prevent race-reduction compiler optimizations. scfcp->scfc_in = true; } smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait); break; case SCF_PRIM_ALL: if (scfsp->scfs_wait) scfp->n_all_wait++; else scfp->n_all++; if (scfcp) { barrier(); // Prevent race-reduction compiler optimizations. scfcp->scfc_in = true; } smp_call_function(scf_handler, scfcp, scfsp->scfs_wait); break; default: WARN_ON_ONCE(1); if (scfcp) scfcp->scfc_out = true; } if (scfcp && scfsp->scfs_wait) { if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) && !scfcp->scfc_out)) { pr_warn("%s: Memory-ordering failure, scfs_prim: %d.\n", __func__, scfsp->scfs_prim); atomic_inc(&n_mb_out_errs); // Leak rather than trash! } else { kfree(scfcp); } barrier(); // Prevent race-reduction compiler optimizations. } if (use_cpus_read_lock) cpus_read_unlock(); else preempt_enable(); if (!(torture_random(trsp) & 0xfff)) schedule_timeout_uninterruptible(1); } // SCF test kthread. Repeatedly does calls to members of the // smp_call_function() family of functions. static int scftorture_invoker(void *arg) { int cpu; int curcpu; DEFINE_TORTURE_RANDOM(rand); struct scf_statistics *scfp = (struct scf_statistics *)arg; bool was_offline = false; VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu); cpu = scfp->cpu % nr_cpu_ids; WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(cpu))); set_user_nice(current, MAX_NICE); if (holdoff) schedule_timeout_interruptible(holdoff * HZ); VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, raw_smp_processor_id()); // Make sure that the CPU is affinitized appropriately during testing. curcpu = raw_smp_processor_id(); WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids, "%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n", __func__, scfp->cpu, curcpu, nr_cpu_ids); if (!atomic_dec_return(&n_started)) while (atomic_read_acquire(&n_started)) { if (torture_must_stop()) { VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu); goto end; } schedule_timeout_uninterruptible(1); } VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu); do { scftorture_invoke_one(scfp, &rand); while (cpu_is_offline(cpu) && !torture_must_stop()) { schedule_timeout_interruptible(HZ / 5); was_offline = true; } if (was_offline) { set_cpus_allowed_ptr(current, cpumask_of(cpu)); was_offline = false; } cond_resched(); stutter_wait("scftorture_invoker"); } while (!torture_must_stop()); VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu); end: torture_kthread_stopping("scftorture_invoker"); return 0; } static void scftorture_print_module_parms(const char *tag) { pr_alert(SCFTORT_FLAG "--- %s: verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d use_cpus_read_lock=%d, weight_resched=%d, weight_single=%d, weight_single_rpc=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag, verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter, use_cpus_read_lock, weight_resched, weight_single, weight_single_rpc, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait); } static void scf_cleanup_handler(void *unused) { } static void scf_torture_cleanup(void) { int i; if (torture_cleanup_begin()) return; WRITE_ONCE(scfdone, true); if (nthreads && scf_stats_p) for (i = 0; i < nthreads; i++) torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task); else goto end; smp_call_function(scf_cleanup_handler, NULL, 0); torture_stop_kthread(scf_torture_stats, scf_torture_stats_task); scf_torture_stats_print(); // -After- the stats thread is stopped! kfree(scf_stats_p); // -After- the last stats print has completed! scf_stats_p = NULL; if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs)) scftorture_print_module_parms("End of test: FAILURE"); else if (torture_onoff_failures()) scftorture_print_module_parms("End of test: LOCK_HOTPLUG"); else scftorture_print_module_parms("End of test: SUCCESS"); end: torture_cleanup_end(); } static int __init scf_torture_init(void) { long i; int firsterr = 0; unsigned long weight_resched1 = weight_resched; unsigned long weight_single1 = weight_single; unsigned long weight_single_rpc1 = weight_single_rpc; unsigned long weight_single_wait1 = weight_single_wait; unsigned long weight_many1 = weight_many; unsigned long weight_many_wait1 = weight_many_wait; unsigned long weight_all1 = weight_all; unsigned long weight_all_wait1 = weight_all_wait; if (!torture_init_begin(SCFTORT_STRING, verbose)) return -EBUSY; scftorture_print_module_parms("Start of test"); if (weight_resched <= 0 && weight_single <= 0 && weight_single_rpc <= 0 && weight_single_wait <= 0 && weight_many <= 0 && weight_many_wait <= 0 && weight_all <= 0 && weight_all_wait <= 0) { weight_resched1 = weight_resched == 0 ? 0 : 2 * nr_cpu_ids; weight_single1 = weight_single == 0 ? 0 : 2 * nr_cpu_ids; weight_single_rpc1 = weight_single_rpc == 0 ? 0 : 2 * nr_cpu_ids; weight_single_wait1 = weight_single_wait == 0 ? 0 : 2 * nr_cpu_ids; weight_many1 = weight_many == 0 ? 0 : 2; weight_many_wait1 = weight_many_wait == 0 ? 0 : 2; weight_all1 = weight_all == 0 ? 0 : 1; weight_all_wait1 = weight_all_wait == 0 ? 0 : 1; } else { if (weight_resched == -1) weight_resched1 = 0; if (weight_single == -1) weight_single1 = 0; if (weight_single_rpc == -1) weight_single_rpc1 = 0; if (weight_single_wait == -1) weight_single_wait1 = 0; if (weight_many == -1) weight_many1 = 0; if (weight_many_wait == -1) weight_many_wait1 = 0; if (weight_all == -1) weight_all1 = 0; if (weight_all_wait == -1) weight_all_wait1 = 0; } if (weight_resched1 == 0 && weight_single1 == 0 && weight_single_rpc1 == 0 && weight_single_wait1 == 0 && weight_many1 == 0 && weight_many_wait1 == 0 && weight_all1 == 0 && weight_all_wait1 == 0) { SCFTORTOUT_ERRSTRING("all zero weights makes no sense"); firsterr = -EINVAL; goto unwind; } if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) scf_sel_add(weight_resched1, SCF_PRIM_RESCHED, false); else if (weight_resched1) SCFTORTOUT_ERRSTRING("built as module, weight_resched ignored"); scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false); scf_sel_add(weight_single_rpc1, SCF_PRIM_SINGLE_RPC, true); scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true); scf_sel_add(weight_many1, SCF_PRIM_MANY, false); scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true); scf_sel_add(weight_all1, SCF_PRIM_ALL, false); scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true); scf_sel_dump(); if (onoff_interval > 0) { firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL); if (torture_init_error(firsterr)) goto unwind; } if (shutdown_secs > 0) { firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup); if (torture_init_error(firsterr)) goto unwind; } if (stutter > 0) { firsterr = torture_stutter_init(stutter, stutter); if (torture_init_error(firsterr)) goto unwind; } // Worker tasks invoking smp_call_function(). if (nthreads < 0) nthreads = num_online_cpus(); scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL); if (!scf_stats_p) { SCFTORTOUT_ERRSTRING("out of memory"); firsterr = -ENOMEM; goto unwind; } VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads", nthreads); atomic_set(&n_started, nthreads); for (i = 0; i < nthreads; i++) { scf_stats_p[i].cpu = i; firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i], scf_stats_p[i].task); if (torture_init_error(firsterr)) goto unwind; } if (stat_interval > 0) { firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task); if (torture_init_error(firsterr)) goto unwind; } torture_init_end(); return 0; unwind: torture_init_end(); scf_torture_cleanup(); if (shutdown_secs) { WARN_ON(!IS_MODULE(CONFIG_SCF_TORTURE_TEST)); kernel_power_off(); } return firsterr; } module_init(scf_torture_init); module_exit(scf_torture_cleanup);