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 9278F23183F; Thu, 16 Jul 2026 00:18:14 +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=1784161096; cv=none; b=ASqKR9W1SQQOhiMkP+9OixUdYIqH1s1FboXIKgej0n0C6P2LQJ9R8Vd2eimi30UBM9e022xQnXjymRV4jvM9QqfVWOt8+10vA7UnThJCB3ji/LXIM8WA5NQA6rLtGGf3bA4y0Jl/00ilDxDDsfv09QW3Tgbv04jTrq3rMl9EaIg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784161096; c=relaxed/simple; bh=zvWR6bgmBcz8v6mYV8M7NJqQ2X/y1muO0aIYKPzGGDA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GHeBdl9gJfG2vQN8g3N4VFOnYbgpNOjbujOjZiYRKwaPTFJtaHXDMaQ5mwPdfvkyJbGiHMGhrjGDTx8rZcMN0jXVGvDG98ZG7KTpzk6cWNFHzzgfl9tdt82bI8Cs4a/DurJ/QnFswc1Y2VH4IgK11kPSU0CVt95W80pQPVgn+WE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jMO3Gv6W; 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="jMO3Gv6W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC4331F01561; 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=oO2sm1j7Nq9Prg/AKFwcQRXORcrI5Vi3nU5SVYQ9V+o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jMO3Gv6WanyGQuOXaw2lzBFd5/u6pZ+MdVjYZNK8JeYzxDc1qD+OWTOLyaZaInf8V 8M9Ha7Znzw8mPqCFiPTtk8MzfmFOQKvMZp76wi+UASYp9Jv2JzgktZGr/hlu96JLkb SXzQfGowEZdjpZdAggdvOtX/6LUezTsGOHw+TXdvTTucbeL2XivcgJ4oa0zezwcWZi ll6wE7ZKj4LBVsSlUa7SmzgcX8PAqybMMuiJOCNB3W9eR0jVMbqjWIaOIrZx6z1z1L l0JxAfdT2am61meJe1yUzoxJP2lC0mni99serrlI+I4jUegnTeZBTbi2cRPnrNLykV WgfkrBhzESvdg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 4A6E5CE0F64; 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 16/24] hazptrtorture: Add irq_release to release hazptr from irq Date: Wed, 15 Jul 2026 17:18:01 -0700 Message-Id: <20260716001809.11084-16-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_release module parameter, which specifies how often hazard pointers will be released 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 | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/hazptrtorture.c b/kernel/rcu/hazptrtorture.c index 0752cedb2f5570..fb25f8351659a4 100644 --- a/kernel/rcu/hazptrtorture.c +++ b/kernel/rcu/hazptrtorture.c @@ -33,6 +33,8 @@ 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, irq_release, -1, + "Release 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"); @@ -364,6 +366,16 @@ static void hazptr_torture_acquire(void *hppp_in) hppp->hpp_htp = cur_ops->readlock(&hppp->hpp_hc); } +/* + * Release a hazard pointer from an smp_call_function handler. + */ +static void hazptr_torture_release(void *hppp_in) +{ + struct hazptr_pending *hppp = hppp_in; + + cur_ops->readunlock(&hppp->hpp_hc, hppp->hpp_htp); +} + /* * Do the delay, the accounting, and the release. This in intended to * be invoked from hazptr_torture_reader, but also for hazard pointers @@ -372,6 +384,7 @@ static void hazptr_torture_acquire(void *hppp_in) static void hazptr_torture_reader_tail(struct hazptr_pending *hppp, struct torture_random_state *trsp) { + int cpu; struct hazptr_ctx *hcp = &hppp->hpp_hc; struct hazptr_torture *htp = hppp->hpp_htp; int pipe_count; @@ -388,7 +401,13 @@ hazptr_torture_reader_tail(struct hazptr_pending *hppp, struct torture_random_st rcu_ftrace_dump(DUMP_ALL); __this_cpu_inc(hazptr_torture_count[pipe_count]); preempt_enable(); - cur_ops->readunlock(hcp, htp); + if (irq_release && !(torture_random(trsp) % irq_release)) { + guard(preempt)(); + cpu = cpumask_next_wrap(smp_processor_id(), cpu_online_mask); + smp_call_function_single(cpu, hazptr_torture_release, hppp, 1); + } else { + cur_ops->readunlock(hcp, htp); + } } /* @@ -660,14 +679,14 @@ hazptr_torture_print_module_parms(struct hazptr_torture_ops *cur_ops, const char { pr_alert("%s" TORTURE_FLAG "--- %s: nreaders=%d nwriters=%d " - "defer_modulus=%d irq_acquire=%d kthread_do_pending_ms=%d " + "defer_modulus=%d irq_acquire=%d irq_release=%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, nwriters, - defer_modulus, irq_acquire, kthread_do_pending_ms, + defer_modulus, irq_acquire, irq_release, kthread_do_pending_ms, onoff_interval, onoff_holdoff, preempt_duration, preempt_interval, reader_sleep_us, @@ -818,6 +837,13 @@ static int __init hazptr_torture_init(void) WARN_ON(IS_BUILTIN(CONFIG_HAZPTR_TORTURE_TEST)); irq_acquire = 0; } + if (irq_release == -1) { + irq_release = 1000 * nr_cpu_ids; + } else if (irq_release < 0) { + pr_alert("Cannot have irq_release (%d) < -1, disabling.\n", irq_release); + WARN_ON(IS_BUILTIN(CONFIG_HAZPTR_TORTURE_TEST)); + irq_release = 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