From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753425AbdLMCyl (ORCPT ); Tue, 12 Dec 2017 21:54:41 -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 S1752685AbdLMB4f (ORCPT ); Tue, 12 Dec 2017 20:56:35 -0500 From: alexander.levin@verizon.com Cc: Nicholas Piggin , Michael Ellerman , alexander.levin@verizon.com X-Host: endeavour.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.14 38/60] powerpc/xmon: Avoid tripping SMP hardlockup watchdog Thread-Topic: [PATCH AUTOSEL for 4.14 38/60] powerpc/xmon: Avoid tripping SMP hardlockup watchdog Thread-Index: AQHTc7VuYoCFJV5PrEayyibtvfInCw== Date: Wed, 13 Dec 2017 01:55:20 +0000 Message-ID: <20171213015455.6455-38-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 vBD2sjc1025464 From: Nicholas Piggin [ Upstream commit 064996d62a33ffe10264b5af5dca92d54f60f806 ] The SMP hardlockup watchdog cross-checks other CPUs for lockups, which causes xmon headaches because it's assuming interrupts hard disabled means no watchdog troubles. Try to improve that by calling touch_nmi_watchdog() in obvious places where secondaries are spinning. Also annotate these spin loops with spin_begin/end calls. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/xmon/xmon.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 33351c6704b1..d9a12102b111 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -530,14 +530,19 @@ static int xmon_core(struct pt_regs *regs, int fromipi) waiting: secondary = 1; + spin_begin(); while (secondary && !xmon_gate) { if (in_xmon == 0) { - if (fromipi) + if (fromipi) { + spin_end(); goto leave; + } secondary = test_and_set_bit(0, &in_xmon); } - barrier(); + spin_cpu_relax(); + touch_nmi_watchdog(); } + spin_end(); if (!secondary && !xmon_gate) { /* we are the first cpu to come in */ @@ -568,21 +573,25 @@ static int xmon_core(struct pt_regs *regs, int fromipi) mb(); xmon_gate = 1; barrier(); + touch_nmi_watchdog(); } cmdloop: while (in_xmon) { if (secondary) { + spin_begin(); if (cpu == xmon_owner) { if (!test_and_set_bit(0, &xmon_taken)) { secondary = 0; + spin_end(); continue; } /* missed it */ while (cpu == xmon_owner) - barrier(); + spin_cpu_relax(); } - barrier(); + spin_cpu_relax(); + touch_nmi_watchdog(); } else { cmd = cmds(regs); if (cmd != 0) { -- 2.11.0