From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4157kH6JYXzDqsx for ; Wed, 13 Jun 2018 11:01:43 +1000 (AEST) From: Ricardo Neri To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Andi Kleen , Ashok Raj , Borislav Petkov , Tony Luck , "Ravi V. Shankar" , x86@kernel.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Ricardo Neri , Jacob Pan , "Rafael J. Wysocki" , Don Zickus , Nicholas Piggin , Michael Ellerman , Frederic Weisbecker , Alexei Starovoitov , Babu Moger , Mathieu Desnoyers , Masami Hiramatsu , Peter Zijlstra , Andrew Morton , Philippe Ombredanne , Colin Ian King , Byungchul Park , "Paul E. McKenney" , "Luis R. Rodriguez" , Waiman Long , Josh Poimboeuf , Randy Dunlap , Davidlohr Bueso , Christoffer Dall , Marc Zyngier , Kai-Heng Feng , Konrad Rzeszutek Wilk , David Rientjes , iommu@lists.linux-foundation.org Subject: [RFC PATCH 22/23] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Date: Tue, 12 Jun 2018 17:57:42 -0700 Message-Id: <1528851463-21140-23-git-send-email-ricardo.neri-calderon@linux.intel.com> In-Reply-To: <1528851463-21140-1-git-send-email-ricardo.neri-calderon@linux.intel.com> References: <1528851463-21140-1-git-send-email-ricardo.neri-calderon@linux.intel.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Keep the HPET-based hardlockup detector disabled unless explicitly enabled via a command line argument. If such parameter is not given, the hardlockup detector will fallback to use the perf-based implementation. The function hardlockup_panic_setup() is updated to return 0 in order to to allow __setup functions of specific hardlockup detectors (in this case hardlockup_detector_hpet_setup()) to inspect the nmi_watchdog boot parameter. Cc: Ashok Raj Cc: Andi Kleen Cc: Tony Luck Cc: Borislav Petkov Cc: Jacob Pan Cc: "Rafael J. Wysocki" Cc: Don Zickus Cc: Nicholas Piggin Cc: Michael Ellerman Cc: Frederic Weisbecker Cc: Alexei Starovoitov Cc: Babu Moger Cc: Mathieu Desnoyers Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Andrew Morton Cc: Philippe Ombredanne Cc: Colin Ian King Cc: Byungchul Park Cc: "Paul E. McKenney" Cc: "Luis R. Rodriguez" Cc: Waiman Long Cc: Josh Poimboeuf Cc: Randy Dunlap Cc: Davidlohr Bueso Cc: Christoffer Dall Cc: Marc Zyngier Cc: Kai-Heng Feng Cc: Konrad Rzeszutek Wilk Cc: David Rientjes Cc: "Ravi V. Shankar" Cc: x86@kernel.org Cc: iommu@lists.linux-foundation.org Signed-off-by: Ricardo Neri -- checkpatch gives the following warning: CHECK: __setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); This is a false-positive as the option nmi_watchdog is already documented. The option is re-evaluated in this file as well. --- Documentation/admin-guide/kernel-parameters.txt | 5 ++++- kernel/watchdog.c | 2 +- kernel/watchdog_hld_hpet.c | 13 +++++++++++++ 3 files changed, 18 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f2040d4..a8833c7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2577,7 +2577,7 @@ Format: [state][,regs][,debounce][,die] nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels - Format: [panic,][nopanic,][num] + Format: [panic,][nopanic,][num,][hpet] Valid num: 0 or 1 0 - turn hardlockup detector in nmi_watchdog off 1 - turn hardlockup detector in nmi_watchdog on @@ -2587,6 +2587,9 @@ please see 'nowatchdog'. This is useful when you use a panic=... timeout and need the box quickly up again. + When hpet is specified, the NMI watchdog will be driven + by an HPET timer, if available in the system. Otherwise, + the perf-based implementation will be used. These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. diff --git a/kernel/watchdog.c b/kernel/watchdog.c index b94bbe3..b5ce6e4 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -84,7 +84,7 @@ static int __init hardlockup_panic_setup(char *str) nmi_watchdog_user_enabled = 0; else if (!strncmp(str, "1", 1)) nmi_watchdog_user_enabled = 1; - return 1; + return 0; } __setup("nmi_watchdog=", hardlockup_panic_setup); diff --git a/kernel/watchdog_hld_hpet.c b/kernel/watchdog_hld_hpet.c index ebb820d..12e5937 100644 --- a/kernel/watchdog_hld_hpet.c +++ b/kernel/watchdog_hld_hpet.c @@ -17,6 +17,7 @@ #define pr_fmt(fmt) "NMI hpet watchdog: " fmt static struct hpet_hld_data *hld_data; +static bool hardlockup_use_hpet; /** * get_count() - Get the current count of the HPET timer @@ -488,6 +489,15 @@ static void hardlockup_detector_hpet_stop(void) spin_unlock(&hld_data->lock); } +static int __init hardlockup_detector_hpet_setup(char *str) +{ + if (strstr(str, "hpet")) + hardlockup_use_hpet = true; + + return 0; +} +__setup("nmi_watchdog=", hardlockup_detector_hpet_setup); + /** * hardlockup_detector_hpet_init() - Initialize the hardlockup detector * @@ -502,6 +512,9 @@ static int __init hardlockup_detector_hpet_init(void) { int ret; + if (!hardlockup_use_hpet) + return -EINVAL; + if (!is_hpet_enabled()) return -ENODEV; -- 2.7.4