Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965379AbdLVJVY (ORCPT ); Fri, 22 Dec 2017 04:21:24 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:40570 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933881AbdLVJEc (ORCPT ); Fri, 22 Dec 2017 04:04:32 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman , Sasha Levin Subject: [PATCH 4.14 133/159] powerpc/watchdog: Do not trigger SMP crash from touch_nmi_watchdog Date: Fri, 22 Dec 2017 09:46:58 +0100 Message-Id: <20171222084630.897698003@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084623.668990192@linuxfoundation.org> References: <20171222084623.668990192@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1456 Lines: 44 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Piggin [ Upstream commit 80e4d70b06863e0104e5a0dc78aa3710297fbd4b ] In xmon, touch_nmi_watchdog() is not expected to be checking that other CPUs have not touched the watchdog, so the code will just call touch_nmi_watchdog() once before re-enabling hard interrupts. Just update our CPU's state, and ignore apparently stuck SMP threads. Arguably touch_nmi_watchdog should check for SMP lockups, and callers should be fixed, but that's not trivial for the input code of xmon. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/watchdog.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -276,9 +276,12 @@ void arch_touch_nmi_watchdog(void) { unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000; int cpu = smp_processor_id(); + u64 tb = get_tb(); - if (get_tb() - per_cpu(wd_timer_tb, cpu) >= ticks) - watchdog_timer_interrupt(cpu); + if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) { + per_cpu(wd_timer_tb, cpu) = tb; + wd_smp_clear_cpu_pending(cpu, tb); + } } EXPORT_SYMBOL(arch_touch_nmi_watchdog);