Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937588AbdCJNrt (ORCPT ); Fri, 10 Mar 2017 08:47:49 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43467 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934263AbdCJLwU (ORCPT ); Fri, 10 Mar 2017 06:52:20 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, daniel.lezcano@linaro.org, kgene@kernel.org, "Thomas Gleixner" , "Seung-Woo Kim" , linux-arm-kernel@lists.infradead.org, javier@osg.samsung.com, cw00.choi@samsung.com, krzk@kernel.org, linux-samsung-soc@vger.kernel.org, "Joonyoung Shim" Date: Fri, 10 Mar 2017 11:46:23 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 229/370] clocksource/exynos_mct: Clear interrupt when cpu is shut down In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2062 Lines: 54 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Joonyoung Shim commit bc7c36eedb0c7004aa06c2afc3c5385adada8fa3 upstream. When a CPU goes offline a potentially pending timer interrupt is not cleared. When the CPU comes online again then the pending interrupt is delivered before the per cpu clockevent device is initialized. As a consequence the tick interrupt handler dereferences a NULL pointer. [ 51.251378] Unable to handle kernel NULL pointer dereference at virtual address 00000040 [ 51.289348] task: ee942d00 task.stack: ee960000 [ 51.293861] PC is at tick_periodic+0x38/0xb0 [ 51.298102] LR is at tick_handle_periodic+0x1c/0x90 Clear the pending interrupt in the cpu dying path. Fixes: 56a94f13919c ("clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier") Reported-by: Seung-Woo Kim Signed-off-by: Joonyoung Shim Cc: linux-samsung-soc@vger.kernel.org Cc: cw00.choi@samsung.com Cc: daniel.lezcano@linaro.org Cc: javier@osg.samsung.com Cc: kgene@kernel.org Cc: krzk@kernel.org Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1484628876-22065-1-git-send-email-jy0922.shim@samsung.com Signed-off-by: Thomas Gleixner [bwh: Backported to 3.16: add definition of the 'mevt' variable, added earlier upstream] Signed-off-by: Ben Hutchings --- --- a/drivers/clocksource/exynos_mct.c +++ b/drivers/clocksource/exynos_mct.c @@ -458,10 +458,15 @@ static int exynos4_local_timer_setup(str static void exynos4_local_timer_stop(struct clock_event_device *evt) { + struct mct_clock_event_device *mevt; + + mevt = container_of(evt, struct mct_clock_event_device, evt); + evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt); if (mct_int_type == MCT_INT_SPI) { if (evt->irq != -1) disable_irq_nosync(evt->irq); + exynos4_mct_write(0x1, mevt->base + MCT_L_INT_CSTAT_OFFSET); } else { disable_percpu_irq(mct_irqs[MCT_L0_IRQ]); }