This commit adds the irq_acquire module parameter, which specifies how often hazard pointers will be acquired from an smp_call_function_single() handler. For example, a value of 10 would result in one of of ten hazard-pointer acquisitions taking place in a handler, and probably also death by excessive numbers of handlers. A value of zero disables, and a value of -1 makes the frequency decrease as a function of the number of CPUs.
Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/hazptrtorture.c | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/hazptrtorture.c b/kernel/rcu/hazptrtorture.c index 8b1315e2d1d1a6..3304eb450d7e32 100644 --- a/kernel/rcu/hazptrtorture.c +++ b/kernel/rcu/hazptrtorture.c @@ -31,6 +31,8 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <[email protected]>"); torture_param(int, defer_modulus, -1, "Defer once per specified # of hazptr ops, zero to disable"); +torture_param(int, irq_acquire, -1, + "Acquire hazard pointers from irq handlers once per specified #, zero to disable"); torture_param(int, kthread_do_pending_ms, -1, "Delay between cleanups for deferred hazard pointers (ms), zero to disable"); torture_param(int, nreaders, -1, "Number of hazard-pointer reader threads"); @@ -351,6 +353,16 @@ hazptr_torture_writer(void *arg) return 0; } +/* + * Acquire a hazard pointer from an smp_call_function handler. + */ +static void hazptr_torture_acquire(void *hppp_in) +{ + struct hazptr_pending *hppp = hppp_in; + + hppp->hpp_htp = cur_ops->readlock(&hppp->hpp_hc); +} + /* * Do the delay, the accounting, and the release. This in intended to * be invoked from hazptr_torture_reader, but also for hazard pointers @@ -399,6 +411,7 @@ static void hazptr_torture_defer(struct hazptr_pending *hppp, struct torture_ran static int hazptr_torture_reader(void *arg) { bool can_defer = !cur_ops->onstack_ctx && kthread_do_pending_ms && defer_modulus; + int cpu = 0; struct hazptr_pending hpp; struct hazptr_pending *hppp = cur_ops->onstack_ctx ? &hpp : NULL; unsigned long lastsleep = jiffies; @@ -417,7 +430,16 @@ static int hazptr_torture_reader(void *arg) continue; } } - hppp->hpp_htp = cur_ops->readlock(&hppp->hpp_hc); + if (irq_acquire && !(torture_random(&rand) % irq_acquire)) { + guard(preempt)(); + cpu = cpumask_next_wrap(cpu, cpu_online_mask); + if (cpu != smp_processor_id()) + smp_call_function_single(cpu, hazptr_torture_acquire, hppp, 1); + else + hppp->hpp_htp = cur_ops->readlock(&hppp->hpp_hc); + } else { + hppp->hpp_htp = cur_ops->readlock(&hppp->hpp_hc); + } if (!hppp->hpp_htp) { // Still starting up, so get out of the way. schedule_timeout_interruptible(HZ / 10); @@ -635,14 +657,14 @@ hazptr_torture_print_module_parms(struct hazptr_torture_ops *cur_ops, const char { pr_alert("%s" TORTURE_FLAG "--- %s: nreaders=%d " - "defer_modulus=%d kthread_do_pending_ms=%d " + "defer_modulus=%d irq_acquire=%d kthread_do_pending_ms=%d " "onoff_interval=%d onoff_holdoff=%d " "preempt_duration=%d preempt_interval=%d " "reader_sleep_us=%d " "shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d " "verbose=%d\n", torture_type, tag, nrealreaders, - defer_modulus, kthread_do_pending_ms, + defer_modulus, irq_acquire, kthread_do_pending_ms, onoff_interval, onoff_holdoff, preempt_duration, preempt_interval, reader_sleep_us, @@ -786,6 +808,13 @@ static int __init hazptr_torture_init(void) if (torture_init_error(firsterr)) goto unwind; + if (irq_acquire == -1) { + irq_acquire = 1000 * nr_cpu_ids; + } else if (irq_acquire < 0) { + pr_alert("Cannot have irq_acquire (%d) < -1, disabling.\n", irq_acquire); + WARN_ON(IS_BUILTIN(CONFIG_HAZPTR_TORTURE_TEST)); + irq_acquire = 0; + } reader_tasks = kzalloc_objs(reader_tasks[0], nrealreaders); for (i = 0; i < nrealreaders; i++) { firsterr = torture_create_kthread(hazptr_torture_reader, (void *)i, -- 2.40.1
