From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752270AbdINKyl (ORCPT ); Thu, 14 Sep 2017 06:54:41 -0400 Received: from terminus.zytor.com ([65.50.211.136]:59477 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752200AbdINKyi (ORCPT ); Thu, 14 Sep 2017 06:54:38 -0400 Date: Thu, 14 Sep 2017 03:48:59 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: cmetcalf@mellanox.com, uobergfe@redhat.com, peterz@infradead.org, bigeasy@linutronix.de, akpm@linux-foundation.org, bp@alien8.de, linux-kernel@vger.kernel.org, npiggin@gmail.com, torvalds@linux-foundation.org, hpa@zytor.com, dzickus@redhat.com, mingo@kernel.org, tglx@linutronix.de Reply-To: dzickus@redhat.com, mingo@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, hpa@zytor.com, npiggin@gmail.com, linux-kernel@vger.kernel.org, bp@alien8.de, bigeasy@linutronix.de, peterz@infradead.org, uobergfe@redhat.com, akpm@linux-foundation.org, cmetcalf@mellanox.com In-Reply-To: <20170912194148.019090547@linutronix.de> References: <20170912194148.019090547@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/urgent] watchdog/hardlockup/perf: Implement init time perf validation Git-Commit-ID: 178b9f7a36d2c74a38274b66dd89f53611298a19 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 178b9f7a36d2c74a38274b66dd89f53611298a19 Gitweb: http://git.kernel.org/tip/178b9f7a36d2c74a38274b66dd89f53611298a19 Author: Thomas Gleixner AuthorDate: Tue, 12 Sep 2017 21:37:18 +0200 Committer: Ingo Molnar CommitDate: Thu, 14 Sep 2017 11:41:08 +0200 watchdog/hardlockup/perf: Implement init time perf validation The watchdog tries to create perf events even after it figured out that perf is not functional or the requested event is not supported. That's braindead as this can be done once at init time and if not supported the NMI watchdog can be turned off unconditonally. Implement the perf hardlockup detector functionality for that. This creates a new event create function, which will replace the unholy mess of the existing one in later patches. Signed-off-by: Thomas Gleixner Reviewed-by: Don Zickus Cc: Andrew Morton Cc: Borislav Petkov Cc: Chris Metcalf Cc: Linus Torvalds Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Sebastian Siewior Cc: Ulrich Obergfell Link: http://lkml.kernel.org/r/20170912194148.019090547@linutronix.de Signed-off-by: Ingo Molnar --- include/linux/nmi.h | 8 ++++++-- kernel/watchdog_hld.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+), 2 deletions(-) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index eee255b..72c62a8 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -93,14 +93,18 @@ extern void hardlockup_detector_perf_stop(void); extern void hardlockup_detector_perf_restart(void); extern void hardlockup_detector_perf_disable(void); extern void hardlockup_detector_perf_cleanup(void); +extern int hardlockup_detector_perf_init(void); #else static inline void hardlockup_detector_perf_stop(void) { } static inline void hardlockup_detector_perf_restart(void) { } static inline void hardlockup_detector_perf_disable(void) { } static inline void hardlockup_detector_perf_cleanup(void) { } -#if !defined(CONFIG_HAVE_NMI_WATCHDOG) +# if !defined(CONFIG_HAVE_NMI_WATCHDOG) +static inline int hardlockup_detector_perf_init(void) { return -ENODEV; } static inline void arch_touch_nmi_watchdog(void) {} -#endif +# else +static inline int hardlockup_detector_perf_init(void) { return 0; } +# endif #endif void watchdog_nmi_reconfigure(bool run); diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 0aa191e..f7e752e 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -238,6 +238,27 @@ out: return 0; } +static int hardlockup_detector_event_create(void) +{ + unsigned int cpu = smp_processor_id(); + struct perf_event_attr *wd_attr; + struct perf_event *evt; + + wd_attr = &wd_hw_attr; + wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); + + /* Try to register using hardware perf events */ + evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL, + watchdog_overflow_callback, NULL); + if (IS_ERR(evt)) { + pr_info("Perf event create on CPU %d failed with %ld\n", cpu, + PTR_ERR(evt)); + return PTR_ERR(evt); + } + this_cpu_write(watchdog_ev, evt); + return 0; +} + /** * hardlockup_detector_perf_disable - Disable the local event */ @@ -315,3 +336,19 @@ void __init hardlockup_detector_perf_restart(void) perf_event_enable(event); } } + +/** + * hardlockup_detector_perf_init - Probe whether NMI event is available at all + */ +int __init hardlockup_detector_perf_init(void) +{ + int ret = hardlockup_detector_event_create(); + + if (ret) { + pr_info("Perf NMI watchdog permanetely disabled\n"); + } else { + perf_event_release_kernel(this_cpu_read(watchdog_ev)); + this_cpu_write(watchdog_ev, NULL); + } + return ret; +}