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![Guilherme G. Piccoli](/assets/img/avatar_default.png)
After a recent change introduced by Vlastimil's series [0], kernel is able now to handle sysctl parameters on kernel command line; also, the series introduced a simple infrastructure to convert legacy boot parameters (that duplicate sysctls) into sysctl aliases. This patch converts the watchdog parameters softlockup_panic and {hard,soft}lockup_all_cpu_backtrace to use the new alias infrastructure. It fixes the documentation too, since the alias only accepts values 0 or 1, not the full range of integers. We also took the opportunity here to improve the documentation of the previously converted hung_task_panic (see the patch series [0]) and put the alias table in alphabetical order. [0] http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Link: http://lkml.kernel.org/r/20200507214624.21911-1-gpiccoli@canonical.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
753 lines
20 KiB
C
753 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Detect hard and soft lockups on a system
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*
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* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
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*
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* Note: Most of this code is borrowed heavily from the original softlockup
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* detector, so thanks to Ingo for the initial implementation.
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* Some chunks also taken from the old x86-specific nmi watchdog code, thanks
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* to those contributors as well.
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*/
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#define pr_fmt(fmt) "watchdog: " fmt
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#include <linux/mm.h>
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#include <linux/cpu.h>
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#include <linux/nmi.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <linux/tick.h>
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#include <linux/sched/clock.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/isolation.h>
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#include <linux/stop_machine.h>
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#include <asm/irq_regs.h>
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#include <linux/kvm_para.h>
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static DEFINE_MUTEX(watchdog_mutex);
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#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
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# define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED)
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# define NMI_WATCHDOG_DEFAULT 1
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#else
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# define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED)
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# define NMI_WATCHDOG_DEFAULT 0
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#endif
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unsigned long __read_mostly watchdog_enabled;
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int __read_mostly watchdog_user_enabled = 1;
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int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT;
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int __read_mostly soft_watchdog_user_enabled = 1;
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int __read_mostly watchdog_thresh = 10;
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static int __read_mostly nmi_watchdog_available;
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static struct cpumask watchdog_allowed_mask __read_mostly;
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struct cpumask watchdog_cpumask __read_mostly;
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unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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# ifdef CONFIG_SMP
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int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
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# endif /* CONFIG_SMP */
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/*
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* Should we panic when a soft-lockup or hard-lockup occurs:
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*/
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unsigned int __read_mostly hardlockup_panic =
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CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
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/*
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* We may not want to enable hard lockup detection by default in all cases,
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* for example when running the kernel as a guest on a hypervisor. In these
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* cases this function can be called to disable hard lockup detection. This
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* function should only be executed once by the boot processor before the
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* kernel command line parameters are parsed, because otherwise it is not
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* possible to override this in hardlockup_panic_setup().
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*/
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void __init hardlockup_detector_disable(void)
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{
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nmi_watchdog_user_enabled = 0;
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}
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static int __init hardlockup_panic_setup(char *str)
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{
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if (!strncmp(str, "panic", 5))
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hardlockup_panic = 1;
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else if (!strncmp(str, "nopanic", 7))
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hardlockup_panic = 0;
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else if (!strncmp(str, "0", 1))
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nmi_watchdog_user_enabled = 0;
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else if (!strncmp(str, "1", 1))
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nmi_watchdog_user_enabled = 1;
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return 1;
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}
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__setup("nmi_watchdog=", hardlockup_panic_setup);
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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/*
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* These functions can be overridden if an architecture implements its
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* own hardlockup detector.
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*
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* watchdog_nmi_enable/disable can be implemented to start and stop when
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* softlockup watchdog threads start and stop. The arch must select the
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* SOFTLOCKUP_DETECTOR Kconfig.
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*/
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int __weak watchdog_nmi_enable(unsigned int cpu)
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{
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hardlockup_detector_perf_enable();
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return 0;
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}
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void __weak watchdog_nmi_disable(unsigned int cpu)
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{
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hardlockup_detector_perf_disable();
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}
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/* Return 0, if a NMI watchdog is available. Error code otherwise */
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int __weak __init watchdog_nmi_probe(void)
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{
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return hardlockup_detector_perf_init();
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}
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/**
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* watchdog_nmi_stop - Stop the watchdog for reconfiguration
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*
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* The reconfiguration steps are:
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* watchdog_nmi_stop();
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* update_variables();
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* watchdog_nmi_start();
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*/
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void __weak watchdog_nmi_stop(void) { }
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/**
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* watchdog_nmi_start - Start the watchdog after reconfiguration
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*
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* Counterpart to watchdog_nmi_stop().
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*
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* The following variables have been updated in update_variables() and
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* contain the currently valid configuration:
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* - watchdog_enabled
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* - watchdog_thresh
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* - watchdog_cpumask
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*/
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void __weak watchdog_nmi_start(void) { }
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/**
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* lockup_detector_update_enable - Update the sysctl enable bit
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*
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* Caller needs to make sure that the NMI/perf watchdogs are off, so this
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* can't race with watchdog_nmi_disable().
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*/
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static void lockup_detector_update_enable(void)
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{
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watchdog_enabled = 0;
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if (!watchdog_user_enabled)
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return;
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if (nmi_watchdog_available && nmi_watchdog_user_enabled)
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watchdog_enabled |= NMI_WATCHDOG_ENABLED;
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if (soft_watchdog_user_enabled)
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watchdog_enabled |= SOFT_WATCHDOG_ENABLED;
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}
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#ifdef CONFIG_SOFTLOCKUP_DETECTOR
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#define SOFTLOCKUP_RESET ULONG_MAX
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#ifdef CONFIG_SMP
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int __read_mostly sysctl_softlockup_all_cpu_backtrace;
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#endif
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/* Global variables, exported for sysctl */
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unsigned int __read_mostly softlockup_panic =
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CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
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static bool softlockup_initialized __read_mostly;
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static u64 __read_mostly sample_period;
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static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
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static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
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static DEFINE_PER_CPU(bool, softlockup_touch_sync);
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static DEFINE_PER_CPU(bool, soft_watchdog_warn);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
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static unsigned long soft_lockup_nmi_warn;
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static int __init nowatchdog_setup(char *str)
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{
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watchdog_user_enabled = 0;
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return 1;
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}
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__setup("nowatchdog", nowatchdog_setup);
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static int __init nosoftlockup_setup(char *str)
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{
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soft_watchdog_user_enabled = 0;
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return 1;
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}
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__setup("nosoftlockup", nosoftlockup_setup);
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static int __init watchdog_thresh_setup(char *str)
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{
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get_option(&str, &watchdog_thresh);
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return 1;
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}
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__setup("watchdog_thresh=", watchdog_thresh_setup);
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static void __lockup_detector_cleanup(void);
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/*
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* Hard-lockup warnings should be triggered after just a few seconds. Soft-
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* lockups can have false positives under extreme conditions. So we generally
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* want a higher threshold for soft lockups than for hard lockups. So we couple
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* the thresholds with a factor: we make the soft threshold twice the amount of
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* time the hard threshold is.
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*/
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static int get_softlockup_thresh(void)
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{
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return watchdog_thresh * 2;
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}
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/*
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* Returns seconds, approximately. We don't need nanosecond
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* resolution, and we don't need to waste time with a big divide when
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* 2^30ns == 1.074s.
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*/
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static unsigned long get_timestamp(void)
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{
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return running_clock() >> 30LL; /* 2^30 ~= 10^9 */
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}
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static void set_sample_period(void)
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{
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/*
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* convert watchdog_thresh from seconds to ns
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* the divide by 5 is to give hrtimer several chances (two
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* or three with the current relation between the soft
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* and hard thresholds) to increment before the
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* hardlockup detector generates a warning
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*/
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sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
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watchdog_update_hrtimer_threshold(sample_period);
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}
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/* Commands for resetting the watchdog */
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static void __touch_watchdog(void)
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{
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__this_cpu_write(watchdog_touch_ts, get_timestamp());
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}
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/**
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* touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
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*
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* Call when the scheduler may have stalled for legitimate reasons
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* preventing the watchdog task from executing - e.g. the scheduler
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* entering idle state. This should only be used for scheduler events.
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* Use touch_softlockup_watchdog() for everything else.
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*/
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notrace void touch_softlockup_watchdog_sched(void)
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{
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/*
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* Preemption can be enabled. It doesn't matter which CPU's timestamp
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* gets zeroed here, so use the raw_ operation.
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*/
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raw_cpu_write(watchdog_touch_ts, SOFTLOCKUP_RESET);
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}
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notrace void touch_softlockup_watchdog(void)
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{
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touch_softlockup_watchdog_sched();
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wq_watchdog_touch(raw_smp_processor_id());
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}
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EXPORT_SYMBOL(touch_softlockup_watchdog);
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void touch_all_softlockup_watchdogs(void)
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{
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int cpu;
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/*
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* watchdog_mutex cannpt be taken here, as this might be called
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* from (soft)interrupt context, so the access to
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* watchdog_allowed_cpumask might race with a concurrent update.
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*
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* The watchdog time stamp can race against a concurrent real
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* update as well, the only side effect might be a cycle delay for
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* the softlockup check.
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*/
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for_each_cpu(cpu, &watchdog_allowed_mask)
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per_cpu(watchdog_touch_ts, cpu) = SOFTLOCKUP_RESET;
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wq_watchdog_touch(-1);
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}
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void touch_softlockup_watchdog_sync(void)
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{
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__this_cpu_write(softlockup_touch_sync, true);
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__this_cpu_write(watchdog_touch_ts, SOFTLOCKUP_RESET);
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}
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static int is_softlockup(unsigned long touch_ts)
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{
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unsigned long now = get_timestamp();
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if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
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/* Warn about unreasonable delays. */
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if (time_after(now, touch_ts + get_softlockup_thresh()))
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return now - touch_ts;
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}
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return 0;
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}
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/* watchdog detector functions */
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bool is_hardlockup(void)
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{
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unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
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if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
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return true;
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__this_cpu_write(hrtimer_interrupts_saved, hrint);
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return false;
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}
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static void watchdog_interrupt_count(void)
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{
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__this_cpu_inc(hrtimer_interrupts);
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}
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static DEFINE_PER_CPU(struct completion, softlockup_completion);
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static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
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/*
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* The watchdog thread function - touches the timestamp.
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*
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* It only runs once every sample_period seconds (4 seconds by
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* default) to reset the softlockup timestamp. If this gets delayed
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* for more than 2*watchdog_thresh seconds then the debug-printout
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* triggers in watchdog_timer_fn().
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*/
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static int softlockup_fn(void *data)
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{
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__touch_watchdog();
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complete(this_cpu_ptr(&softlockup_completion));
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return 0;
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}
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/* watchdog kicker functions */
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static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
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{
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unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
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struct pt_regs *regs = get_irq_regs();
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int duration;
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int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
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if (!watchdog_enabled)
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return HRTIMER_NORESTART;
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/* kick the hardlockup detector */
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watchdog_interrupt_count();
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/* kick the softlockup detector */
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if (completion_done(this_cpu_ptr(&softlockup_completion))) {
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reinit_completion(this_cpu_ptr(&softlockup_completion));
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stop_one_cpu_nowait(smp_processor_id(),
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softlockup_fn, NULL,
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this_cpu_ptr(&softlockup_stop_work));
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}
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/* .. and repeat */
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hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
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if (touch_ts == SOFTLOCKUP_RESET) {
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if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
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/*
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* If the time stamp was touched atomically
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* make sure the scheduler tick is up to date.
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*/
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__this_cpu_write(softlockup_touch_sync, false);
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sched_clock_tick();
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}
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/* Clear the guest paused flag on watchdog reset */
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kvm_check_and_clear_guest_paused();
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__touch_watchdog();
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return HRTIMER_RESTART;
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}
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/* check for a softlockup
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* This is done by making sure a high priority task is
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* being scheduled. The task touches the watchdog to
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* indicate it is getting cpu time. If it hasn't then
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* this is a good indication some task is hogging the cpu
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*/
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duration = is_softlockup(touch_ts);
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if (unlikely(duration)) {
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/*
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* If a virtual machine is stopped by the host it can look to
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* the watchdog like a soft lockup, check to see if the host
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* stopped the vm before we issue the warning
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*/
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if (kvm_check_and_clear_guest_paused())
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return HRTIMER_RESTART;
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/* only warn once */
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if (__this_cpu_read(soft_watchdog_warn) == true)
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return HRTIMER_RESTART;
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if (softlockup_all_cpu_backtrace) {
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/* Prevent multiple soft-lockup reports if one cpu is already
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* engaged in dumping cpu back traces
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*/
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if (test_and_set_bit(0, &soft_lockup_nmi_warn)) {
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/* Someone else will report us. Let's give up */
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__this_cpu_write(soft_watchdog_warn, true);
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return HRTIMER_RESTART;
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}
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}
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pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
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smp_processor_id(), duration,
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current->comm, task_pid_nr(current));
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print_modules();
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print_irqtrace_events(current);
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if (regs)
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show_regs(regs);
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else
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dump_stack();
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if (softlockup_all_cpu_backtrace) {
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/* Avoid generating two back traces for current
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* given that one is already made above
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*/
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trigger_allbutself_cpu_backtrace();
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clear_bit(0, &soft_lockup_nmi_warn);
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/* Barrier to sync with other cpus */
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smp_mb__after_atomic();
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}
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add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
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if (softlockup_panic)
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panic("softlockup: hung tasks");
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__this_cpu_write(soft_watchdog_warn, true);
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} else
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__this_cpu_write(soft_watchdog_warn, false);
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return HRTIMER_RESTART;
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}
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static void watchdog_enable(unsigned int cpu)
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{
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struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
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struct completion *done = this_cpu_ptr(&softlockup_completion);
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WARN_ON_ONCE(cpu != smp_processor_id());
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init_completion(done);
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complete(done);
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/*
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* Start the timer first to prevent the NMI watchdog triggering
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* before the timer has a chance to fire.
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*/
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hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
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hrtimer->function = watchdog_timer_fn;
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hrtimer_start(hrtimer, ns_to_ktime(sample_period),
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HRTIMER_MODE_REL_PINNED_HARD);
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/* Initialize timestamp */
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__touch_watchdog();
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/* Enable the perf event */
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if (watchdog_enabled & NMI_WATCHDOG_ENABLED)
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watchdog_nmi_enable(cpu);
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}
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static void watchdog_disable(unsigned int cpu)
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{
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struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
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WARN_ON_ONCE(cpu != smp_processor_id());
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/*
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* Disable the perf event first. That prevents that a large delay
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* between disabling the timer and disabling the perf event causes
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* the perf NMI to detect a false positive.
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*/
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watchdog_nmi_disable(cpu);
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hrtimer_cancel(hrtimer);
|
|
wait_for_completion(this_cpu_ptr(&softlockup_completion));
|
|
}
|
|
|
|
static int softlockup_stop_fn(void *data)
|
|
{
|
|
watchdog_disable(smp_processor_id());
|
|
return 0;
|
|
}
|
|
|
|
static void softlockup_stop_all(void)
|
|
{
|
|
int cpu;
|
|
|
|
if (!softlockup_initialized)
|
|
return;
|
|
|
|
for_each_cpu(cpu, &watchdog_allowed_mask)
|
|
smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);
|
|
|
|
cpumask_clear(&watchdog_allowed_mask);
|
|
}
|
|
|
|
static int softlockup_start_fn(void *data)
|
|
{
|
|
watchdog_enable(smp_processor_id());
|
|
return 0;
|
|
}
|
|
|
|
static void softlockup_start_all(void)
|
|
{
|
|
int cpu;
|
|
|
|
cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
|
|
for_each_cpu(cpu, &watchdog_allowed_mask)
|
|
smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
|
|
}
|
|
|
|
int lockup_detector_online_cpu(unsigned int cpu)
|
|
{
|
|
if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
|
|
watchdog_enable(cpu);
|
|
return 0;
|
|
}
|
|
|
|
int lockup_detector_offline_cpu(unsigned int cpu)
|
|
{
|
|
if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
|
|
watchdog_disable(cpu);
|
|
return 0;
|
|
}
|
|
|
|
static void lockup_detector_reconfigure(void)
|
|
{
|
|
cpus_read_lock();
|
|
watchdog_nmi_stop();
|
|
|
|
softlockup_stop_all();
|
|
set_sample_period();
|
|
lockup_detector_update_enable();
|
|
if (watchdog_enabled && watchdog_thresh)
|
|
softlockup_start_all();
|
|
|
|
watchdog_nmi_start();
|
|
cpus_read_unlock();
|
|
/*
|
|
* Must be called outside the cpus locked section to prevent
|
|
* recursive locking in the perf code.
|
|
*/
|
|
__lockup_detector_cleanup();
|
|
}
|
|
|
|
/*
|
|
* Create the watchdog thread infrastructure and configure the detector(s).
|
|
*
|
|
* The threads are not unparked as watchdog_allowed_mask is empty. When
|
|
* the threads are successfully initialized, take the proper locks and
|
|
* unpark the threads in the watchdog_cpumask if the watchdog is enabled.
|
|
*/
|
|
static __init void lockup_detector_setup(void)
|
|
{
|
|
/*
|
|
* If sysctl is off and watchdog got disabled on the command line,
|
|
* nothing to do here.
|
|
*/
|
|
lockup_detector_update_enable();
|
|
|
|
if (!IS_ENABLED(CONFIG_SYSCTL) &&
|
|
!(watchdog_enabled && watchdog_thresh))
|
|
return;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
lockup_detector_reconfigure();
|
|
softlockup_initialized = true;
|
|
mutex_unlock(&watchdog_mutex);
|
|
}
|
|
|
|
#else /* CONFIG_SOFTLOCKUP_DETECTOR */
|
|
static void lockup_detector_reconfigure(void)
|
|
{
|
|
cpus_read_lock();
|
|
watchdog_nmi_stop();
|
|
lockup_detector_update_enable();
|
|
watchdog_nmi_start();
|
|
cpus_read_unlock();
|
|
}
|
|
static inline void lockup_detector_setup(void)
|
|
{
|
|
lockup_detector_reconfigure();
|
|
}
|
|
#endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
|
|
|
|
static void __lockup_detector_cleanup(void)
|
|
{
|
|
lockdep_assert_held(&watchdog_mutex);
|
|
hardlockup_detector_perf_cleanup();
|
|
}
|
|
|
|
/**
|
|
* lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes
|
|
*
|
|
* Caller must not hold the cpu hotplug rwsem.
|
|
*/
|
|
void lockup_detector_cleanup(void)
|
|
{
|
|
mutex_lock(&watchdog_mutex);
|
|
__lockup_detector_cleanup();
|
|
mutex_unlock(&watchdog_mutex);
|
|
}
|
|
|
|
/**
|
|
* lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
|
|
*
|
|
* Special interface for parisc. It prevents lockup detector warnings from
|
|
* the default pm_poweroff() function which busy loops forever.
|
|
*/
|
|
void lockup_detector_soft_poweroff(void)
|
|
{
|
|
watchdog_enabled = 0;
|
|
}
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
|
|
/* Propagate any changes to the watchdog threads */
|
|
static void proc_watchdog_update(void)
|
|
{
|
|
/* Remove impossible cpus to keep sysctl output clean. */
|
|
cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
|
|
lockup_detector_reconfigure();
|
|
}
|
|
|
|
/*
|
|
* common function for watchdog, nmi_watchdog and soft_watchdog parameter
|
|
*
|
|
* caller | table->data points to | 'which'
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED |
|
|
* | | SOFT_WATCHDOG_ENABLED
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED
|
|
*/
|
|
static int proc_watchdog_common(int which, struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err, old, *param = table->data;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
if (!write) {
|
|
/*
|
|
* On read synchronize the userspace interface. This is a
|
|
* racy snapshot.
|
|
*/
|
|
*param = (watchdog_enabled & which) != 0;
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
} else {
|
|
old = READ_ONCE(*param);
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (!err && old != READ_ONCE(*param))
|
|
proc_watchdog_update();
|
|
}
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/watchdog
|
|
*/
|
|
int proc_watchdog(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
|
|
table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/nmi_watchdog
|
|
*/
|
|
int proc_nmi_watchdog(struct ctl_table *table, int write,
|
|
void *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);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/soft_watchdog
|
|
*/
|
|
int proc_soft_watchdog(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
|
|
table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/watchdog_thresh
|
|
*/
|
|
int proc_watchdog_thresh(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err, old;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
old = READ_ONCE(watchdog_thresh);
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
|
|
if (!err && write && old != READ_ONCE(watchdog_thresh))
|
|
proc_watchdog_update();
|
|
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* The cpumask is the mask of possible cpus that the watchdog can run
|
|
* on, not the mask of cpus it is actually running on. This allows the
|
|
* user to specify a mask that will include cpus that have not yet
|
|
* been brought online, if desired.
|
|
*/
|
|
int proc_watchdog_cpumask(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
|
|
if (!err && write)
|
|
proc_watchdog_update();
|
|
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
void __init lockup_detector_init(void)
|
|
{
|
|
if (tick_nohz_full_enabled())
|
|
pr_info("Disabling watchdog on nohz_full cores by default\n");
|
|
|
|
cpumask_copy(&watchdog_cpumask,
|
|
housekeeping_cpumask(HK_FLAG_TIMER));
|
|
|
|
if (!watchdog_nmi_probe())
|
|
nmi_watchdog_available = true;
|
|
lockup_detector_setup();
|
|
}
|