From patchwork Thu Mar 12 09:11:36 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Damian Eppel X-Patchwork-Id: 5992211 Return-Path: X-Original-To: patchwork-linux-samsung-soc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A92A6BF90F for ; Thu, 12 Mar 2015 09:12:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A08DA20384 for ; Thu, 12 Mar 2015 09:12:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54F8520383 for ; Thu, 12 Mar 2015 09:12:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751857AbbCLJL4 (ORCPT ); Thu, 12 Mar 2015 05:11:56 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:52726 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750977AbbCLJLx (ORCPT ); Thu, 12 Mar 2015 05:11:53 -0400 Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NL300D3SDJRDQ20@mailout1.samsung.com>; Thu, 12 Mar 2015 18:11:51 +0900 (KST) X-AuditID: cbfee61b-f79d76d0000024d6-05-55015857f984 Received: from epmmp2 ( [203.254.227.17]) by epcpsbgm2.samsung.com (EPCPMTA) with SMTP id 4C.43.09430.75851055; Thu, 12 Mar 2015 18:11:51 +0900 (KST) Received: from AMDC1552.DIGITAL.local ([106.120.221.142]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0NL300BLCDJFXK30@mmp2.samsung.com>; Thu, 12 Mar 2015 18:11:51 +0900 (KST) From: Damian Eppel To: daniel.lezcano@linaro.org Cc: tglx@linutronix.de, kgene@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, kyungmin.park@samsung.com, k.kozlowski@samsung.com, m.jabrzyk@samsung.com, Damian Eppel , stable@vger.kernel.org Subject: [PATCH v2] clocksource: exynos_mct: fix for sleeping in atomic ctx handling cpu hotplug notif. Date: Thu, 12 Mar 2015 10:11:36 +0100 Message-id: <1426151496-5509-1-git-send-email-d.eppel@samsung.com> X-Mailer: git-send-email 1.9.1 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprELMWRmVeSWpSXmKPExsVy+t9jQd3wCMZQg2enFS0uPXrJZjHvs6zF 6xeGFv2PXzNbnG16w26x6fE1VovLu+awWcw4v4/JYtr5bkaLBRsfMVps3jSV2YHbY9OqTjaP O9f2sHm8O3eO3WPzknqPvi2rGD0+b5ILYIvisklJzcksSy3St0vgyvg66T5zwR2TiqtLzjM2 MP7V7mLk5JAQMJHYf7uLCcIWk7hwbz1bFyMXh5DAdEaJtWs6mCGcTiaJ7U9PsoFUsQloSDSv 3gxmiwjISjy6P5cdpIhZYA6TxK7dd1hBEsICmRLL1hxlB7FZBFQlPj/7ChTn4OAVcJJYeZMd YpucxMljk1knMHIvYGRYxSiaWpBcUJyUnmukV5yYW1yal66XnJ+7iREcUs+kdzCuarA4xCjA wajEw3vhO0OoEGtiWXFl7iFGCQ5mJRFeCVfGUCHelMTKqtSi/Pii0pzU4kOM0hwsSuK8SvZt IUIC6YklqdmpqQWpRTBZJg5OqQbGZfxmJ7bXPjouu6xQ/Uyd1Ofilsj7nHwfNgnOmfjG+tcX xwUF619eF/+uGOsZ7D9757pjjCyTqipUpwcprVWbLXgqv+hPT2kIZ/m/lXKFlZsXiAXVl9XW JUUH2RssWbDHZtmTiQX679QNzHruvJp7MFSr4ZqehFvZ16uSeTYZN84rsaQ6PQtSYinOSDTU Yi4qTgQAikxpaiUCAAA= Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This is to fix an issue of sleeping in atomic context when processing hotplug notifications in Exynos MCT(Multi-Core Timer). The issue was reproducible on Exynos 3250 (Rinato board) and Exynos 5420 (Arndale Octa board). Whilst testing cpu hotplug events on kernel configured with DEBUG_PREEMPT and DEBUG_ATOMIC_SLEEP we get following BUG message, caused by calling request_irq() and free_irq() in the context of hotplug notification (which is in this case atomic context). root@target:~# echo 0 > /sys/devices/system/cpu/cpu1/online [ 25.157867] IRQ18 no longer affine to CPU1 ... [ 25.158445] CPU1: shutdown root@target:~# echo 1 > /sys/devices/system/cpu/cpu1/online [ 40.785859] CPU1: Software reset [ 40.786660] BUG: sleeping function called from invalid context at mm/slub.c:1241 [ 40.786668] in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/1 [ 40.786678] Preemption disabled at:[< (null)>] (null) [ 40.786681] [ 40.786692] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.19.0-rc4-00024-g7dca860 #36 [ 40.786698] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [ 40.786728] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 40.786747] [] (show_stack) from [] (dump_stack+0x70/0xbc) [ 40.786767] [] (dump_stack) from [] (kmem_cache_alloc+0xd8/0x170) [ 40.786785] [] (kmem_cache_alloc) from [] (request_threaded_irq+0x64/0x128) [ 40.786804] [] (request_threaded_irq) from [] (exynos4_local_timer_setup+0xc0/0x13c) [ 40.786820] [] (exynos4_local_timer_setup) from [] (exynos4_mct_cpu_notify+0x30/0xa8) [ 40.786838] [] (exynos4_mct_cpu_notify) from [] (notifier_call_chain+0x44/0x84) [ 40.786857] [] (notifier_call_chain) from [] (__cpu_notify+0x28/0x44) [ 40.786873] [] (__cpu_notify) from [] (secondary_start_kernel+0xec/0x150) [ 40.786886] [] (secondary_start_kernel) from [<40008764>] (0x40008764) Solution: Clockevent irqs cannot be requested/freed every time cpu is hot-plugged/unplugged as CPU_STARTING/CPU_DYING notifications that signals hotplug or unplug events are sent with both preemption and local interrupts disabled. Since request_irq() may sleep it is moved to the initialization stage and performed for all possible cpus prior putting them online. Then, in the case of hotplug event the irq asociated with the given cpu will simply be enabled. Similarly on cpu unplug event the interrupt is not freed but just disabled. Note that after successful request_irq() call for a clockevent device associated to given cpu the requested irq is disabled (via disable_irq()). That is to make things symmetric as we expect hotplug event as a next thing (which will enable irq again). This should not pose any problems because at the time of requesting irq the clockevent device is not fully initialized yet, therefore should not produce interrupts at that point. For disabling an irq at cpu unplug notification disable_irq_nosync() is chosen which is a non-blocking function. This again shouldn't be a problem as prior sending CPU_DYING notification interrupts are migrated away from the cpu. Fixes: 7114cd749a12 ("clocksource: exynos_mct: use (request/free)_irq calls for local timer registration") Signed-off-by: Damian Eppel Cc: Reported-by: Krzysztof Kozlowski Reviewed-by: Krzysztof Kozlowski Tested-by: Krzysztof Kozlowski (Tested on Arndale Octa Board) Tested-by: Marcin Jabrzyk (Tested on Rinato B2 (Exynos 3250) board) --- Notes: Changes since v1: o added Krzysztof's and Marcin's Reviewed-by / Tested-by with information about the test HW. drivers/clocksource/exynos_mct.c | 45 ++++++++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 13 deletions(-) diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c index 83564c9..9beca58 100644 --- a/drivers/clocksource/exynos_mct.c +++ b/drivers/clocksource/exynos_mct.c @@ -466,15 +466,12 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt) exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET); if (mct_int_type == MCT_INT_SPI) { - evt->irq = mct_irqs[MCT_L0_IRQ + cpu]; - if (request_irq(evt->irq, exynos4_mct_tick_isr, - IRQF_TIMER | IRQF_NOBALANCING, - evt->name, mevt)) { - pr_err("exynos-mct: cannot register IRQ %d\n", - evt->irq); + + if (evt->irq == -1) return -EIO; - } - irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu)); + + irq_force_affinity(evt->irq, cpumask_of(cpu)); + enable_irq(evt->irq); } else { enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0); } @@ -487,10 +484,12 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt) static void exynos4_local_timer_stop(struct clock_event_device *evt) { evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt); - if (mct_int_type == MCT_INT_SPI) - free_irq(evt->irq, this_cpu_ptr(&percpu_mct_tick)); - else + if (mct_int_type == MCT_INT_SPI) { + if (evt->irq != -1) + disable_irq_nosync(evt->irq); + } else { disable_percpu_irq(mct_irqs[MCT_L0_IRQ]); + } } static int exynos4_mct_cpu_notify(struct notifier_block *self, @@ -522,7 +521,7 @@ static struct notifier_block exynos4_mct_cpu_nb = { static void __init exynos4_timer_resources(struct device_node *np, void __iomem *base) { - int err; + int err, cpu; struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick); struct clk *mct_clk, *tick_clk; @@ -549,7 +548,27 @@ static void __init exynos4_timer_resources(struct device_node *np, void __iomem WARN(err, "MCT: can't request IRQ %d (%d)\n", mct_irqs[MCT_L0_IRQ], err); } else { - irq_set_affinity(mct_irqs[MCT_L0_IRQ], cpumask_of(0)); + for_each_possible_cpu(cpu) { + int mct_irq = mct_irqs[MCT_L0_IRQ + cpu]; + struct mct_clock_event_device *pcpu_mevt = + per_cpu_ptr(&percpu_mct_tick, cpu); + + pcpu_mevt->evt.irq = -1; + + if (request_irq(mct_irq, + exynos4_mct_tick_isr, + IRQF_TIMER | IRQF_NOBALANCING, + pcpu_mevt->name, pcpu_mevt)) { + pr_err("exynos-mct: cannot register IRQ (cpu%d)\n", + cpu); + + continue; + } + pcpu_mevt->evt.irq = mct_irq; + irq_force_affinity(mct_irq, cpumask_of(cpu)); + + disable_irq(mct_irq); + } } err = register_cpu_notifier(&exynos4_mct_cpu_nb);