From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE527C6FD1D for ; Fri, 31 Mar 2023 01:47:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229685AbjCaBrs (ORCPT ); Thu, 30 Mar 2023 21:47:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229553AbjCaBrq (ORCPT ); Thu, 30 Mar 2023 21:47:46 -0400 Received: from out28-196.mail.aliyun.com (out28-196.mail.aliyun.com [115.124.28.196]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E6683A8C for ; Thu, 30 Mar 2023 18:47:24 -0700 (PDT) X-Alimail-AntiSpam: AC=CONTINUE;BC=0.09924161|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_system_inform|0.130828-0.218845-0.650328;FP=0|0|0|0|0|-1|-1|-1;HT=ay29a033018047213;MF=victor@allwinnertech.com;NM=1;PH=DS;RN=5;RT=5;SR=0;TI=SMTPD_---.S3TkIzr_1680227199; Received: from 192.168.220.144(mailfrom:victor@allwinnertech.com fp:SMTPD_---.S3TkIzr_1680227199) by smtp.aliyun-inc.com; Fri, 31 Mar 2023 09:46:40 +0800 Message-ID: <3d95e6bf-bc69-0b04-8835-7fcd746ed9d6@allwinnertech.com> Date: Fri, 31 Mar 2023 09:46:39 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH] tick/broadcast: Do not set oneshot_mask except was_periodic was true Content-Language: en-US From: Victor Hassan To: fweisbec@gmail.com, tglx@linutronix.de, mingo@kernel.org, jindong.yue@nxp.com Cc: linux-kernel@vger.kernel.org References: <20230328063629.108510-1-victor@allwinnertech.com> In-Reply-To: <20230328063629.108510-1-victor@allwinnertech.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/28/2023 2:36 PM, Victor Hassan wrote: > If a broadcast timer is registered after the system switched to oneshot > mode, a hang_task err could occur like that: > > INFO: task kworker/u15:0:7 blocked for more than 120 seconds. > Tainted: G E 5.15.41-android13-8-00002-xxx #1 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:kworker/u16:0 state:D stack: 9808 pid: 7 ppid: 2 flags:0x00000008 > Workqueue: events_unbound deferred_probe_work_func.cfi_jt > Call trace: > __switch_to+0y240/0x490 > __schedule+0x620/0xafc > schedule+0x110/0x204 > schedule_hrtimeout_range_clock+0x9c/0x118 > usleep_range_state+0x150/0x1ac > _regulator_do_enable+0x528/0x878 > set_machine_constraints+0x6a0/0xf2c > regulator_register+0x3ac/0x7ac > devm_regulator_register+0xbc/0x120 > pmu_ext_regulator_probe+0xb0/0x1b4 [pmu_ext_regulator] > platform_probe+0x70/0x194 > really_proe+0x320/0x68c > __driver_probe_device+0x204/0x260 > driver_probe_device+0x48/0x1e0 > > When the new broadcast timer was registered after the system switched > to oneshot mode, the broadcast timer was not used as periodic. If the > oneshot mask was set incorrectly, all cores which did not enter cpu_idle > state can't enter cpu_idle normally, causing the hrtimer mechanism to > break. > > This patch fixes the issue by moving the update action about oneshot > mask to a more strict conditions. The tick_broadcast_setup_oneshot would > be called in two typical condition, and they all will work. > > 1. tick_handle_periodic -> tick_broadcast_setup_oneshot > > The origin broadcast was periodic, so it can set the oneshot_mask bits > for those waiting for periodic broadcast and program the broadcast timer > to fire. > > 2. tick_install_broadcast_device -> tick_broadcast_setup_oneshot > > The origin broadcast was oneshot, so the cores which enter the cpu_idle > already used the oneshot_mask bits. It is unnecessary to update the > oneshot_mask. > > Fixes: 9c336c9935cf ("tick/broadcast: Allow late registered device to enter oneshot mode") > > Signed-off-by: Victor Hassan > --- > kernel/time/tick-broadcast.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > index 93bf2b4e47e5..fdbbba487978 100644 > --- a/kernel/time/tick-broadcast.c > +++ b/kernel/time/tick-broadcast.c > @@ -1041,12 +1041,13 @@ static void tick_broadcast_setup_oneshot(struct clock_event_device *bc) > */ > cpumask_copy(tmpmask, tick_broadcast_mask); > cpumask_clear_cpu(cpu, tmpmask); > - cpumask_or(tick_broadcast_oneshot_mask, > - tick_broadcast_oneshot_mask, tmpmask); > > if (was_periodic && !cpumask_empty(tmpmask)) { > ktime_t nextevt = tick_get_next_period(); > > + cpumask_or(tick_broadcast_oneshot_mask, > + tick_broadcast_oneshot_mask, tmpmask); > + > clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT); > tick_broadcast_init_next_event(tmpmask, nextevt); > tick_broadcast_set_event(bc, cpu, nextevt); Friendly ping.