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[tip:core/urgent] watchdog/hardlockup/perf: Implement init time detection of perf

From tip-bot for Thomas Gleixner <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:core/urgent] watchdog/hardlockup/perf: Implement init time detection of perf
Date 2017-09-14 13:00 +0200
Message-ID <upA2f-3WF-37@gated-at.bofh.it> (permalink)
References <uoZvK-5zK-65@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  a994a3147e4c0c9c50a46e6cace7586254975e20
Gitweb:     http://git.kernel.org/tip/a994a3147e4c0c9c50a46e6cace7586254975e20
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 12 Sep 2017 21:37:19 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 14 Sep 2017 11:41:08 +0200

watchdog/hardlockup/perf: Implement init time detection of perf

Use the init time detection of the perf NMI watchdog to determine whether
the perf NMI watchdog is functional. If not disable it permanentely. It
won't come back magically at runtime.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Don Zickus <dzickus@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Link: http://lkml.kernel.org/r/20170912194148.099799541@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/watchdog.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 8488631..fd8a998 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -44,6 +44,7 @@ int __read_mostly watchdog_user_enabled = 1;
 int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT;
 int __read_mostly soft_watchdog_user_enabled = 1;
 int __read_mostly watchdog_thresh = 10;
+int __read_mostly nmi_watchdog_available;
 
 struct cpumask watchdog_allowed_mask __read_mostly;
 static bool softlockup_threads_initialized __read_mostly;
@@ -114,6 +115,12 @@ void __weak watchdog_nmi_disable(unsigned int cpu)
 	hardlockup_detector_perf_disable();
 }
 
+/* Return 0, if a NMI watchdog is available. Error code otherwise */
+int __weak __init watchdog_nmi_probe(void)
+{
+	return hardlockup_detector_perf_init();
+}
+
 /**
  * watchdog_nmi_reconfigure - Optional function to reconfigure NMI watchdogs
  * @run:	If false stop the watchdogs on all enabled CPUs
@@ -145,7 +152,7 @@ static void lockup_detector_update_enable(void)
 	watchdog_enabled = 0;
 	if (!watchdog_user_enabled)
 		return;
-	if (nmi_watchdog_user_enabled)
+	if (nmi_watchdog_available && nmi_watchdog_user_enabled)
 		watchdog_enabled |= NMI_WATCHDOG_ENABLED;
 	if (soft_watchdog_user_enabled)
 		watchdog_enabled |= SOFT_WATCHDOG_ENABLED;
@@ -692,6 +699,8 @@ int proc_watchdog(struct ctl_table *table, int write,
 int proc_nmi_watchdog(struct ctl_table *table, int write,
 		      void __user *buffer, size_t *lenp, loff_t *ppos)
 {
+	if (!nmi_watchdog_available && write)
+		return -ENOTSUPP;
 	return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
 				    table, write, buffer, lenp, ppos);
 }
@@ -764,5 +773,7 @@ void __init lockup_detector_init(void)
 	cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
 #endif
 
+	if (!watchdog_nmi_probe())
+		nmi_watchdog_available = true;
 	softlockup_init_threads();
 }

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Thread

[patch V2 00/29] lockup_detector: Cure hotplug deadlocks and replace  duct tape Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 21:50 +0200
  [patch V2 14/29] lockup_detector: Split out cpumask write function Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 21:50 +0200
    [tip:core/urgent] watchdog/core: Split out cpumask write function tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 05/29] lockup_detector: Remove broken suspend/resume  interfaces Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 21:50 +0200
    [tip:core/urgent] watchdog/core: Remove broken suspend/resume  interfaces tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 16/29] lockup_detector: Create new thread handling  infrastructure Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 21:50 +0200
    [tip:core/urgent] watchdog/core: Create new thread handling  infrastructure tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 01/29] hardlockup_detector: Provide interface to  stop/restart perf events Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 21:50 +0200
    [tip:core/urgent] watchdog/hardlockup: Provide interface to  stop/restart perf events tip-bot for Peter Zijlstra <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 26/29] lockup_detector/perf: Implement CPU enable  replacement Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Implement CPU enable  replacement tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 06/29] lockup_detector: Rework cpu hotplug locking Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Rework CPU hotplug locking tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 28/29] lockup_detector/perf: Simplify deferred event destroy Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Simplify deferred event  destroy tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 04/29] parisc: Use lockup_detector_stop() Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    Re: [patch V2 04/29] parisc: Use lockup_detector_stop() Helge Deller <deller@gmx.de> - 2017-09-14 11:10 +0200
      Re: [patch V2 04/29] parisc: Use lockup_detector_stop() Don Zickus <dzickus@redhat.com> - 2017-09-14 15:50 +0200
    [tip:core/urgent] parisc, watchdog/core: Use lockup_detector_stop() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 17/29] lockup_detector: Get rid of the thread  teardown/setup dance Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Get rid of the thread  teardown/setup dance tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 03/29] lockup_detector: Provide interface to stop from  poweroff() Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Provide interface to stop from  poweroff() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 10/29] lockup_detector/perf: Prevent cpu hotplug deadlock Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Prevent CPU hotplug  deadlock tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 13/29] lockup_detector: Cleanup the ifdef maze Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Clean up the #ifdef maze tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 29/29] lockup_detector: Cleanup hotplug locking mess Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup: Clean up hotplug locking  mess tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 09/29] lockup_detector/perf: Remove broken self disable on  failure Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Remove broken self  disable on failure tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 08/29] lockup_detector: Mark hardlockup_detector_disable()  __init Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Mark hardlockup_detector_disable()  __init tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 12:50 +0200
  [patch V2 18/29] lockup_detector: Further simplify sysctl handling Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Further simplify sysctl handling tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 12/29] lockup_detector: Cleanup stub functions Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Clean up stub functions tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 15/29] smpboot/threads: Avoid runtime allocation Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] smpboot/threads, watchdog/core: Avoid runtime  allocation tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 20/29] lockup_detector/sysctl: Get rid of the ifdeffery Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/sysctl: Get rid of the #ifdeffery tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 27/29] lockup_detector: Use new perf CPU enable mechanism Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Use new perf CPU enable  mechanism tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 24/29] lockup_detector/perf: Implement init time perf  validation Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Implement init time  perf validation tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 19/29] lockup_detector: Cleanup header mess Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Clean up header mess tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 22/29] lockup_detector: Make watchdog_nmi_reconfigure() two  stage Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core, powerpc: Make  watchdog_nmi_reconfigure() two stage tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 25/29] lockup_detector: Implement init time detection of  perf Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    Re: [patch V2 25/29] lockup_detector: Implement init time detection  of perf Don Zickus <dzickus@redhat.com> - 2017-09-13 20:10 +0200
      Re: [patch V2 25/29] lockup_detector: Implement init time detection  of perf Thomas Gleixner <tglx@linutronix.de> - 2017-09-13 20:10 +0200
        Re: [patch V2 25/29] lockup_detector: Implement init time detection  of perf Ingo Molnar <mingo@kernel.org> - 2017-09-14 07:30 +0200
    [tip:core/urgent] watchdog/hardlockup/perf: Implement init time  detection of perf tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  [patch V2 23/29] lockup_detector: Get rid of the racy update loop Thomas Gleixner <tglx@linutronix.de> - 2017-09-12 22:00 +0200
    [tip:core/urgent] watchdog/core: Get rid of the racy update loop tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-09-14 13:00 +0200
  Re: [patch V2 00/29] lockup_detector: Cure hotplug deadlocks and  replace duct tape Don Zickus <dzickus@redhat.com> - 2017-09-13 20:10 +0200
    Re: [patch V2 00/29] lockup_detector: Cure hotplug deadlocks and  replace duct tape Ingo Molnar <mingo@kernel.org> - 2017-09-14 07:30 +0200
    Re: [patch V2 00/29] lockup_detector: Cure hotplug deadlocks and  replace duct tape Thomas Gleixner <tglx@linutronix.de> - 2017-09-14 10:20 +0200

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