From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6E44221FCD; Thu, 16 Jul 2026 00:18:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784161095; cv=none; b=lj+TofzPKUGyor6t0Q+0ytkOS74DT8yaHKqaGKGlObv96CzfbsophPxUJY/HVAD2rCOvWibKi8I/lC3jdvIswoKWeKD11Wp5YY/LLB5LJZJRF6uhHRSE53JinZwchcfjYT0N4TPfAeJLaZGfGqmVIRJg2nZ7pQwSAsMOW7DoudY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784161095; c=relaxed/simple; bh=M6BVgZFSjILX5HaRUmyWETnbG02BYPqnpcsDUfsXXbA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qKe8l7ZhYWp44E6Ot8GSSnKffzljVXPq6i3ZAJX6WdKwzezL0a4y1sCRcOa/rcPexjijCsYV9/O3ZGaWau0Ak4O6EMQeLgnCl05NE4EHRWMHQBD/mDjAhOyQ7U0xv+cbsOhyBJ/9q7uXjWyS8tK0i0ciC3Oa+2W1FHY2sA32kEs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ddsru8iT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ddsru8iT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A75F11F01560; Thu, 16 Jul 2026 00:18:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784161091; bh=o2QKJb1SmUARMMLEAEctoR5D5DIckgM5bthyhdFJHLg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ddsru8iTWOAIVD8vlpGVCpkR7Vm+Abkp36rkU4MrtLBVenOxLqj2uGVENQM/bjhWO uBbGB8hoi42udhDib2CP7I8VRlQddoyhwezzffXNC8qsK1GqJuDHo7UmMXLWQJ/Dh5 b9bapr1KaVhR+zdB30lbiYUMBnUXzN8x1d+8frNjIiJS19MkdcoylPvfXQMLGX/o/t NxPs62NBCTOVUeGg9Egvo3e0vZ8Nv3SqQFIKj9fHsYp1J8n2EPaLsU9EdfMtQtDOJE cgwg+MuqqonfXp8Ty2PVOdouORzzZpsLIJBN/l7SHs5R7Pabh1eEHzxRKAu01ofvDf xRILLdytXXt2Q== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 408A3CE0E8C; Wed, 15 Jul 2026 17:18:11 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH RFC v2 12/24] hazptrtorture: Add irq_acquire to acquire hazptr from irq Date: Wed, 15 Jul 2026 17:17:57 -0700 Message-Id: <20260716001809.11084-12-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <23e34c2e-67fd-45da-b130-e70a131a59ea@paulmck-laptop> References: <23e34c2e-67fd-45da-b130-e70a131a59ea@paulmck-laptop> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 "); 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