From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753073AbdLMC5t (ORCPT ); Tue, 12 Dec 2017 21:57:49 -0500 Received: from omzsmtpe02.verizonbusiness.com ([199.249.25.209]:59199 "EHLO omzsmtpe02.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752616AbdLMB4W (ORCPT ); Tue, 12 Dec 2017 20:56:22 -0500 From: alexander.levin@verizon.com Cc: Nicholas Piggin , Michael Ellerman , alexander.levin@verizon.com X-Host: surveyor.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.14 39/60] powerpc/watchdog: Do not trigger SMP crash from touch_nmi_watchdog Thread-Topic: [PATCH AUTOSEL for 4.14 39/60] powerpc/watchdog: Do not trigger SMP crash from touch_nmi_watchdog Thread-Index: AQHTc7Vu1QIjIkTYSEOCn/AAMx8aMg== Date: Wed, 13 Dec 2017 01:55:21 +0000 Message-ID: <20171213015455.6455-39-alexander.levin@verizon.com> References: <20171213015455.6455-1-alexander.levin@verizon.com> In-Reply-To: <20171213015455.6455-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBD2wXGp025932 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 --- arch/powerpc/kernel/watchdog.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index 57190f384f63..ce848ff84edd 100644 --- 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); -- 2.11.0