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 1C28D3314DE; Sat, 19 Sep 2026 00:01:01 +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=1789776064; cv=none; b=qE/LyTUreK4A/Td/JQvPQwQ922MKTU0gBgHiSyb77jfGbDr0Iyreg4VODHXX6WiJDeX1nFn2NF3tCFxb7VWj/7xG68gVl+x53B/8tFsVB4uM4QPQ716Q0l22yGaIyL3rXxJqHDKrE1VaTmNMEVZUDFZcZBvfryNn7M6p4AT8yNQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789776064; c=relaxed/simple; bh=iaZV3IG8J0Aiq2rSuuFWdI5UzAZ31i17fi4VmWM2hvc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=LZ1Y/9n4l1laoCuGA+/6tqN99vweMY2CLEIXYieOCN1OuenH31hQlu0sEKkH4UnYxtYs3aNzUGY5NtUyk8T9dLJialx6ko1cjIPvAlUG59T4o73pc5p5bzAHhD7kMRb/EaQmMwO7t9p1YCGLFQ2RG6LyVS9YfHuT78vvROVZ4b0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=orBQ1UXH; 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="orBQ1UXH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E653C1F0089B; Sat, 19 Sep 2026 00:00:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789776060; bh=CnSiDLJ7QHHXSz6IC5OgMA66MRnY2X7v8dzQ1csx5U4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=orBQ1UXHxoeJMcxVxFPHnJ27QqvFxuc8BKb2LuqneWF8NlkUW1qRekAmmfpS9w7kW ejubyANPdn/f0y+sSwd3qVq4I2oNgtCKd6hXtUcHv2assjsjeJF/L51Unv7vN3UE3o ZONiyd5WdRKJu2tErp7e4cil5+oFzD+NoWa6eWwOFVin1ehYR1y2N3x/GOTqSkm3bb tp0qImFujAtHlJYJjqgaYecC7zPz7W2FHz9QHD7b8av8IzpoBqP/dB5Hmt2KTx5HLF YfSSNh1pP9uuHV17NDbcugFknMQ3ql+xAvo6pPPJJBstBuWfC/nwaWOw19P/4r2d/X PL/Zb1wZtzicA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 6C835CE0C44; Fri, 18 Sep 2026 17:00:59 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org, linux-kernel@vger.kernel.org Cc: kernel-team@meta.com, Mathieu Desnoyers , Boqun Feng , Steven Rostedt , lkmm@lists.linux.dev, Zqiang , Wang Lian , Kunwu Chan , Bradley Morgan , "Paul E. McKenney" Subject: [PATCH 12/28] hazptrtorture: Add irq_acquire to acquire hazptr from irq Date: Fri, 18 Sep 2026 17:00:40 -0700 Message-Id: <20260919000056.3132131-12-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@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 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 Cc: Boqun Feng Cc: Mathieu Desnoyers Cc: Cc: --- 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 ff253fe35ca2..dc148894786b 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); @@ -634,14 +656,14 @@ 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, @@ -785,6 +807,13 @@ 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