From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Joonyoung Shim , linux-samsung-soc@vger.kernel.org, cw00.choi@samsung.com, daniel.lezcano@linaro.org, javier@osg.samsung.com, kgene@kernel.org, krzk@kernel.org, linux-arm-kernel@lists.infradead.org, Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 3.18 77/98] clocksource/exynos_mct: Clear interrupt when cpu is shut down Date: Thu, 25 Oct 2018 10:18:32 -0400 Message-Id: <20181025141853.214051-77-sashal@kernel.org> In-Reply-To: <20181025141853.214051-1-sashal@kernel.org> References: <20181025141853.214051-1-sashal@kernel.org> List-ID: From: Joonyoung Shim [ Upstream commit bc7c36eedb0c7004aa06c2afc3c5385adada8fa3 ] 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: stable@vger.kernel.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 Signed-off-by: Sasha Levin --- drivers/clocksource/exynos_mct.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c index c844616028d2..714f9a767b17 100644 --- a/drivers/clocksource/exynos_mct.c +++ b/drivers/clocksource/exynos_mct.c @@ -487,6 +487,7 @@ static void exynos4_local_timer_stop(struct clock_event_device *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]); } -- 2.17.1