From patchwork Tue Jun 2 11:11:45 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Damian Eppel X-Patchwork-Id: 6528331 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 A9C53C0020 for ; Tue, 2 Jun 2015 11:13:48 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 908D92053B for ; Tue, 2 Jun 2015 11:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D26002052D for ; Tue, 2 Jun 2015 11:13:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754071AbbFBLNn (ORCPT ); Tue, 2 Jun 2015 07:13:43 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:40995 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752923AbbFBLNl (ORCPT ); Tue, 2 Jun 2015 07:13:41 -0400 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NPB02MWEDURO9D0@mailout1.samsung.com>; Tue, 02 Jun 2015 20:13:39 +0900 (KST) X-AuditID: cbfee61a-f79516d000006302-bc-556d8fe3b451 Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id 14.06.25346.3EF8D655; Tue, 2 Jun 2015 20:13:39 +0900 (KST) Received: from AMDC1552.DIGITAL.local ([106.120.221.142]) by mmp1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTPA id <0NPB00FZDDU9H140@mmp1.samsung.com>; Tue, 02 Jun 2015 20:13:39 +0900 (KST) From: Damian Eppel To: daniel.lezcano@linaro.org, tglx@linutronix.de, kgene@kernel.org, k.kozlowski@samsung.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org Cc: m.szyprowski@samsung.com, kyungmin.park@samsung.com, m.jabrzyk@samsung.com, d.eppel@samsung.com, stable@vger.kernel.org Subject: [PATCH v3] clocksource: exynos_mct: fix for sleeping in atomic ctx handling cpu hotplug notif. Date: Tue, 02 Jun 2015 13:11:45 +0200 Message-id: <1433243505-3236-1-git-send-email-d.eppel@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1426151496-5509-1-git-send-email-d.eppel@samsung.com> References: <1426151496-5509-1-git-send-email-d.eppel@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrALMWRmVeSWpSXmKPExsVy+t9jAd3H/bmhBqt36llcevSSzWLeZ1mL 1y8MLfofv2a2ONv0ht1i0+NrrBaXd81hs5hxfh+TxbTz3YwWa4/cZbdYsPERo8XmTVOZHXg8 Nq3qZPO4c20Pm8e7c+fYPTYvqffo27KK0ePzJrkAtigum5TUnMyy1CJ9uwSujMXbu5gLjppW LHw5laWB8aJOFyMnh4SAiUTH2vWMELaYxIV769m6GLk4hAQWMUq82tjEDOH8ZpTYdvkhK0gV m4CGRPPqzWBVIgLHGSX6v30GSzAL1Epc/3SaDcQWFsiUaN6/gwXEZhFQlWi5uRNsBa+Ak0Tn kw2sEOvkJE4emwxmcwo4S+y92ARWIwRUc7Czh3kCI+8CRoZVjKKpBckFxUnpuYZ6xYm5xaV5 6XrJ+bmbGMHh+ExqB+PKBotDjAIcjEo8vAyfckKFWBPLiitzDzFKcDArifAebc0NFeJNSays Si3Kjy8qzUktPsQozcGiJM57Mt8nVEggPbEkNTs1tSC1CCbLxMEp1cCo97zlkvVSxUkOXyN3 iSTr+rc+XCy28LTJnL3p89/n88v9Cn9Uz7iEu15D7qv3XFnlXeLuB8VFWz5vWPuhZXZ67YRY yf3B9S/0ZE0nVH2z2b9bS541/ua0CZW72uPz+faHn09a8JCzPMF7zvpK5X8vdxd/WZg0Wcf9 qbpehaVQxo+uwztCr61VYinOSDTUYi4qTgQAWtGha0MCAAA= 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. Changes since v2: o requesting mct_irq already in disabled state instead of calling disable_irq() right after request_irq(). drivers/clocksource/exynos_mct.c | 43 ++++++++++++++++++++++++++++------------ 1 file changed, 30 insertions(+), 13 deletions(-) diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c index 83564c9..c844616 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 +548,25 @@ 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; + + irq_set_status_flags(mct_irq, IRQ_NOAUTOEN); + 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; + } } err = register_cpu_notifier(&exynos4_mct_cpu_nb);