Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933854AbcJZQDz (ORCPT ); Wed, 26 Oct 2016 12:03:55 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:18091 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932995AbcJZQDx (ORCPT ); Wed, 26 Oct 2016 12:03:53 -0400 From: Babu Moger To: mingo@kernel.org, akpm@linux-foundation.org, ak@linux.intel.com, jkosina@suse.cz, baiyaowei@cmss.chinamobile.com, dzickus@redhat.com, atomlin@redhat.com, uobergfe@redhat.com, tj@kernel.org, hidehiro.kawai.ez@hitachi.com, johunt@akamai.com, davem@davemloft.net, sparclinux@vger.kernel.org Cc: bp@suse.de, bywxiaobai@163.com, cmetcalf@mellanox.com, keescook@chromium.org, ebiederm@xmission.com, huawei.libin@huawei.com, ralf@linux-mips.org, dvyukov@google.com, linux-kernel@vger.kernel.org, sam@ravnborg.org, babu.moger@oracle.com Subject: [RFC PATCH 4/4] sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable Date: Wed, 26 Oct 2016 09:02:23 -0700 Message-Id: <1477497743-15357-5-git-send-email-babu.moger@oracle.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1477497743-15357-1-git-send-email-babu.moger@oracle.com> References: <1477497743-15357-1-git-send-email-babu.moger@oracle.com> X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2732 Lines: 99 Implement functions watchdog_nmi_enable and watchdog_nmi_disable to enable/disable nmi watchdog. Sparc uses arch specific nmi watchdog handler. Currently, we do not have a way to enable/disable nmi watchdog dynamically. With these patches we can enable or disable arch specific nmi watchdogs using proc or sysctl interface. Example commands. To enable: echo 1 > /proc/sys/kernel/nmi_watchdog To disable: echo 0 > /proc/sys/kernel/nmi_watchdog It can also achieved using the sysctl parameter kernel.nmi_watchdog Signed-off-by: Babu Moger --- arch/sparc/kernel/nmi.c | 44 +++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 43 insertions(+), 1 deletions(-) diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c index a9973bb..95e73c6 100644 --- a/arch/sparc/kernel/nmi.c +++ b/arch/sparc/kernel/nmi.c @@ -42,7 +42,7 @@ */ atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ EXPORT_SYMBOL(nmi_active); - +static int nmi_init_done; static unsigned int nmi_hz = HZ; static DEFINE_PER_CPU(short, wd_enabled); static int endflag __initdata; @@ -153,6 +153,8 @@ static void report_broken_nmi(int cpu, int *prev_nmi_count) void stop_nmi_watchdog(void *unused) { + if (!__this_cpu_read(wd_enabled)) + return; pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); __this_cpu_write(wd_enabled, 0); atomic_dec(&nmi_active); @@ -207,6 +209,9 @@ static int __init check_nmi_watchdog(void) void start_nmi_watchdog(void *unused) { + if (__this_cpu_read(wd_enabled)) + return; + __this_cpu_write(wd_enabled, 1); atomic_inc(&nmi_active); @@ -259,6 +264,8 @@ int __init nmi_init(void) } } + nmi_init_done = 1; + return err; } @@ -270,3 +277,38 @@ static int __init setup_nmi_watchdog(char *str) return 0; } __setup("nmi_watchdog=", setup_nmi_watchdog); + +/* + * sparc specific NMI watchdog enable function. + * Enables watchdog if it is not enabled already. + */ +int watchdog_nmi_enable(unsigned int cpu) +{ + if (atomic_read(&nmi_active) == -1) { + pr_warn("NMI watchdog cannot be enabled or disabled\n"); + return -1; + } + + /* + * watchdog thread could start even before nmi_init is called. + * Just Return in that case. Let nmi_init finish the init + * process first. + */ + if (!nmi_init_done) + return 0; + + smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1); + + return 0; +} +/* + * sparc specific NMI watchdog disable function. + * Disables watchdog if it is not disabled already. + */ +void watchdog_nmi_disable(unsigned int cpu) +{ + if (atomic_read(&nmi_active) == -1) + pr_warn_once("NMI watchdog cannot be enabled or disabled\n"); + else + smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1); +} -- 1.7.1