This is an attempt to cleanup watchdog handlers. Right now,
kernel/watchdog.c implements both softlockup and hardlockup detectors.
Softlockup code is generic. Hardlockup code is arch specific. Some
architectures don't use hardlockup detectors. They use their own watchdog
detectors. To make both these combination work, we have numerous #ifdefs
in kernel/watchdog.c.
We are trying here to make these handlers independent of each other.
Also provide an interface for architectures to implement their own
handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
as weak such that architectures can override its definitions.
Thanks to Don Zickus for his suggestions.
Here are our previous discussions
http://www.spinics.net/lists/sparclinux/msg16543.html
http://www.spinics.net/lists/sparclinux/msg16441.html
v2:
Addressed few comments from Don Zickus.
1. Took care of bisectability issue. Previous patch2 is patch1 now.
Combined patch 1 and 3. Patch 4 is now patch 3.
2. Added pr_fmt back in watchdog_hld.c
3. Tweaked the file headers for watchdog.c and watchdog_hld.c.
4. Took care of couple of config compile issues.
drivers/edac/edac_device.o:(.discard+0x0): multiple definition of `__pcpu_unique_hrtimer_interrupts'
drivers/edac/edac_mc.o:(.discard+0x0): first defined here
This was a problem with uni processor config. Moved the definition of hrtimer_interrupts and
is_hardlockup into watchdog.c as softlockup code does most of the work here.
is_hardlockup kind of generic most part.
kernel/built-in.o: In function `watchdog_overflow_callback':
watchdog_hld.c:(.text+0x56940): undefined reference to `sysctl_hardlockup_all_cpu_backtrace'
Moved this definition to nmi.h.
v1:
Initial version
Babu Moger (3):
watchdog: Move shared definitions to nmi.h
watchdog: Move hardlockup detector to separate file
sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable
arch/sparc/kernel/nmi.c | 44 ++++++++-
include/linux/nmi.h | 24 ++++
kernel/Makefile | 1 +
kernel/watchdog.c | 270 +++--------------------------------------------
kernel/watchdog_hld.c | 227 +++++++++++++++++++++++++++++++++++++++
5 files changed, 310 insertions(+), 256 deletions(-)
create mode 100644 kernel/watchdog_hld.c
Move shared macros and definitions to nmi.h so that watchdog.c,
new file watchdog_hld.c or any other architecture specific handler
can use those definitions.
Signed-off-by: Babu Moger <[email protected]>
---
include/linux/nmi.h | 24 ++++++++++++++++++++++++
kernel/watchdog.c | 28 ++++------------------------
2 files changed, 28 insertions(+), 24 deletions(-)
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index a78c35c..aacca82 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -7,6 +7,23 @@
#include <linux/sched.h>
#include <asm/irq.h>
+/*
+ * The run state of the lockup detectors is controlled by the content of the
+ * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit -
+ * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector.
+ *
+ * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled'
+ * are variables that are only used as an 'interface' between the parameters
+ * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The
+ * 'watchdog_thresh' variable is handled differently because its value is not
+ * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh'
+ * is equal zero.
+ */
+#define NMI_WATCHDOG_ENABLED_BIT 0
+#define SOFT_WATCHDOG_ENABLED_BIT 1
+#define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT)
+#define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT)
+
/**
* touch_nmi_watchdog - restart NMI watchdog timeout.
*
@@ -91,9 +108,16 @@ static inline bool trigger_single_cpu_backtrace(int cpu)
extern int soft_watchdog_enabled;
extern int watchdog_user_enabled;
extern int watchdog_thresh;
+extern unsigned long watchdog_enabled;
extern unsigned long *watchdog_cpumask_bits;
+#ifdef CONFIG_SMP
extern int sysctl_softlockup_all_cpu_backtrace;
extern int sysctl_hardlockup_all_cpu_backtrace;
+#else
+#define sysctl_softlockup_all_cpu_backtrace 0
+#define sysctl_hardlockup_all_cpu_backtrace 0
+#endif
+extern bool is_hardlockup(void);
struct ctl_table;
extern int proc_watchdog(struct ctl_table *, int ,
void __user *, size_t *, loff_t *);
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9acb29f..0424301 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -27,29 +27,12 @@
#include <linux/perf_event.h>
#include <linux/kthread.h>
-/*
- * The run state of the lockup detectors is controlled by the content of the
- * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit -
- * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector.
- *
- * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled'
- * are variables that are only used as an 'interface' between the parameters
- * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The
- * 'watchdog_thresh' variable is handled differently because its value is not
- * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh'
- * is equal zero.
- */
-#define NMI_WATCHDOG_ENABLED_BIT 0
-#define SOFT_WATCHDOG_ENABLED_BIT 1
-#define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT)
-#define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT)
-
static DEFINE_MUTEX(watchdog_proc_mutex);
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
+#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
+unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
#else
-static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
+unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
#endif
int __read_mostly nmi_watchdog_enabled;
int __read_mostly soft_watchdog_enabled;
@@ -59,9 +42,6 @@
#ifdef CONFIG_SMP
int __read_mostly sysctl_softlockup_all_cpu_backtrace;
int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
-#else
-#define sysctl_softlockup_all_cpu_backtrace 0
-#define sysctl_hardlockup_all_cpu_backtrace 0
#endif
static struct cpumask watchdog_cpumask __read_mostly;
unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
@@ -289,7 +269,7 @@ void touch_softlockup_watchdog_sync(void)
#ifdef CONFIG_HARDLOCKUP_DETECTOR
/* watchdog detector functions */
-static bool is_hardlockup(void)
+bool is_hardlockup(void)
{
unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
--
1.7.1
Separate hardlockup code from watchdog.c and move it to watchdog_hld.c.
It is mostly straight forward. Remove everything inside
CONFIG_HARDLOCKUP_DETECTORS. This code will go to file watchdog_hld.c.
Also update the makefile accordigly.
Signed-off-by: Babu Moger <[email protected]>
---
kernel/Makefile | 1 +
kernel/watchdog.c | 242 ++----------------------------------------------
kernel/watchdog_hld.c | 227 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 239 insertions(+), 231 deletions(-)
create mode 100644 kernel/watchdog_hld.c
diff --git a/kernel/Makefile b/kernel/Makefile
index eb26e12..314e7d6 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_KGDB) += debug/
obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o
obj-$(CONFIG_LOCKUP_DETECTOR) += watchdog.o
+obj-$(CONFIG_HARDLOCKUP_DETECTOR) += watchdog_hld.o
obj-$(CONFIG_SECCOMP) += seccomp.o
obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 0424301..d4b0fa0 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -24,7 +24,6 @@
#include <asm/irq_regs.h>
#include <linux/kvm_para.h>
-#include <linux/perf_event.h>
#include <linux/kthread.h>
static DEFINE_MUTEX(watchdog_proc_mutex);
@@ -80,50 +79,9 @@
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved);
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static DEFINE_PER_CPU(bool, hard_watchdog_warn);
-static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
-static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
-#endif
static unsigned long soft_lockup_nmi_warn;
-/* boot commands */
-/*
- * Should we panic when a soft-lockup or hard-lockup occurs:
- */
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-unsigned int __read_mostly hardlockup_panic =
- CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
-static unsigned long hardlockup_allcpu_dumped;
-/*
- * We may not want to enable hard lockup detection by default in all cases,
- * for example when running the kernel as a guest on a hypervisor. In these
- * cases this function can be called to disable hard lockup detection. This
- * function should only be executed once by the boot processor before the
- * kernel command line parameters are parsed, because otherwise it is not
- * possible to override this in hardlockup_panic_setup().
- */
-void hardlockup_detector_disable(void)
-{
- watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
-}
-
-static int __init hardlockup_panic_setup(char *str)
-{
- if (!strncmp(str, "panic", 5))
- hardlockup_panic = 1;
- else if (!strncmp(str, "nopanic", 7))
- hardlockup_panic = 0;
- else if (!strncmp(str, "0", 1))
- watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
- else if (!strncmp(str, "1", 1))
- watchdog_enabled |= NMI_WATCHDOG_ENABLED;
- return 1;
-}
-__setup("nmi_watchdog=", hardlockup_panic_setup);
-#endif
-
unsigned int __read_mostly softlockup_panic =
CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
@@ -244,30 +202,12 @@ void touch_all_softlockup_watchdogs(void)
wq_watchdog_touch(-1);
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-void touch_nmi_watchdog(void)
-{
- /*
- * Using __raw here because some code paths have
- * preemption enabled. If preemption is enabled
- * then interrupts should be enabled too, in which
- * case we shouldn't have to worry about the watchdog
- * going off.
- */
- raw_cpu_write(watchdog_nmi_touch, true);
- touch_softlockup_watchdog();
-}
-EXPORT_SYMBOL(touch_nmi_watchdog);
-
-#endif
-
void touch_softlockup_watchdog_sync(void)
{
__this_cpu_write(softlockup_touch_sync, true);
__this_cpu_write(watchdog_touch_ts, 0);
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
/* watchdog detector functions */
bool is_hardlockup(void)
{
@@ -279,7 +219,6 @@ bool is_hardlockup(void)
__this_cpu_write(hrtimer_interrupts_saved, hrint);
return false;
}
-#endif
static int is_softlockup(unsigned long touch_ts)
{
@@ -293,78 +232,22 @@ static int is_softlockup(unsigned long touch_ts)
return 0;
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-
-static struct perf_event_attr wd_hw_attr = {
- .type = PERF_TYPE_HARDWARE,
- .config = PERF_COUNT_HW_CPU_CYCLES,
- .size = sizeof(struct perf_event_attr),
- .pinned = 1,
- .disabled = 1,
-};
-
-/* Callback function for perf event subsystem */
-static void watchdog_overflow_callback(struct perf_event *event,
- struct perf_sample_data *data,
- struct pt_regs *regs)
-{
- /* Ensure the watchdog never gets throttled */
- event->hw.interrupts = 0;
-
- if (__this_cpu_read(watchdog_nmi_touch) == true) {
- __this_cpu_write(watchdog_nmi_touch, false);
- return;
- }
-
- /* check for a hardlockup
- * This is done by making sure our timer interrupt
- * is incrementing. The timer interrupt should have
- * fired multiple times before we overflow'd. If it hasn't
- * then this is a good indication the cpu is stuck
- */
- if (is_hardlockup()) {
- int this_cpu = smp_processor_id();
- struct pt_regs *regs = get_irq_regs();
-
- /* only print hardlockups once */
- if (__this_cpu_read(hard_watchdog_warn) == true)
- return;
-
- pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
- print_modules();
- print_irqtrace_events(current);
- if (regs)
- show_regs(regs);
- else
- dump_stack();
-
- /*
- * Perform all-CPU dump only once to avoid multiple hardlockups
- * generating interleaving traces
- */
- if (sysctl_hardlockup_all_cpu_backtrace &&
- !test_and_set_bit(0, &hardlockup_allcpu_dumped))
- trigger_allbutself_cpu_backtrace();
-
- if (hardlockup_panic)
- nmi_panic(regs, "Hard LOCKUP");
-
- __this_cpu_write(hard_watchdog_warn, true);
- return;
- }
-
- __this_cpu_write(hard_watchdog_warn, false);
- return;
-}
-#endif /* CONFIG_HARDLOCKUP_DETECTOR */
-
static void watchdog_interrupt_count(void)
{
__this_cpu_inc(hrtimer_interrupts);
}
-static int watchdog_nmi_enable(unsigned int cpu);
-static void watchdog_nmi_disable(unsigned int cpu);
+/*
+ * These two functions are mostly architecture specific
+ * defining them as weak here.
+ */
+int __weak watchdog_nmi_enable(unsigned int cpu)
+{
+ return 0;
+}
+void __weak watchdog_nmi_disable(unsigned int cpu)
+{
+}
static int watchdog_enable_all_cpus(void);
static void watchdog_disable_all_cpus(void);
@@ -557,109 +440,6 @@ static void watchdog(unsigned int cpu)
watchdog_nmi_disable(cpu);
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-/*
- * People like the simple clean cpu node info on boot.
- * Reduce the watchdog noise by only printing messages
- * that are different from what cpu0 displayed.
- */
-static unsigned long cpu0_err;
-
-static int watchdog_nmi_enable(unsigned int cpu)
-{
- struct perf_event_attr *wd_attr;
- struct perf_event *event = per_cpu(watchdog_ev, cpu);
-
- /* nothing to do if the hard lockup detector is disabled */
- if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
- goto out;
-
- /* is it already setup and enabled? */
- if (event && event->state > PERF_EVENT_STATE_OFF)
- goto out;
-
- /* it is setup but not enabled */
- if (event != NULL)
- goto out_enable;
-
- wd_attr = &wd_hw_attr;
- wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
-
- /* Try to register using hardware perf events */
- event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
-
- /* save cpu0 error for future comparision */
- if (cpu == 0 && IS_ERR(event))
- cpu0_err = PTR_ERR(event);
-
- if (!IS_ERR(event)) {
- /* only print for cpu0 or different than cpu0 */
- if (cpu == 0 || cpu0_err)
- pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
- goto out_save;
- }
-
- /*
- * Disable the hard lockup detector if _any_ CPU fails to set up
- * set up the hardware perf event. The watchdog() function checks
- * the NMI_WATCHDOG_ENABLED bit periodically.
- *
- * The barriers are for syncing up watchdog_enabled across all the
- * cpus, as clear_bit() does not use barriers.
- */
- smp_mb__before_atomic();
- clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
- smp_mb__after_atomic();
-
- /* skip displaying the same error again */
- if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
- return PTR_ERR(event);
-
- /* vary the KERN level based on the returned errno */
- if (PTR_ERR(event) == -EOPNOTSUPP)
- pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
- else if (PTR_ERR(event) == -ENOENT)
- pr_warn("disabled (cpu%i): hardware events not enabled\n",
- cpu);
- else
- pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
- cpu, PTR_ERR(event));
-
- pr_info("Shutting down hard lockup detector on all cpus\n");
-
- return PTR_ERR(event);
-
- /* success path */
-out_save:
- per_cpu(watchdog_ev, cpu) = event;
-out_enable:
- perf_event_enable(per_cpu(watchdog_ev, cpu));
-out:
- return 0;
-}
-
-static void watchdog_nmi_disable(unsigned int cpu)
-{
- struct perf_event *event = per_cpu(watchdog_ev, cpu);
-
- if (event) {
- perf_event_disable(event);
- per_cpu(watchdog_ev, cpu) = NULL;
-
- /* should be in cleanup, but blocks oprofile */
- perf_event_release_kernel(event);
- }
- if (cpu == 0) {
- /* watchdog_nmi_enable() expects this to be zero initially. */
- cpu0_err = 0;
- }
-}
-
-#else
-static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
-static void watchdog_nmi_disable(unsigned int cpu) { return; }
-#endif /* CONFIG_HARDLOCKUP_DETECTOR */
-
static struct smp_hotplug_thread watchdog_threads = {
.store = &softlockup_watchdog,
.thread_should_run = watchdog_should_run,
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
new file mode 100644
index 0000000..1f5127b
--- /dev/null
+++ b/kernel/watchdog_hld.c
@@ -0,0 +1,227 @@
+/*
+ * Detect hard lockups on a system
+ *
+ * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
+ *
+ * Note: Most of this code is borrowed heavily from the original softlockup
+ * detector, so thanks to Ingo for the initial implementation.
+ * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
+ * to those contributors as well.
+ */
+
+#define pr_fmt(fmt) "NMI watchdog: " fmt
+
+#include <linux/nmi.h>
+#include <linux/module.h>
+#include <asm/irq_regs.h>
+#include <linux/perf_event.h>
+
+static DEFINE_PER_CPU(bool, hard_watchdog_warn);
+static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
+static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
+
+/* boot commands */
+/*
+ * Should we panic when a soft-lockup or hard-lockup occurs:
+ */
+unsigned int __read_mostly hardlockup_panic =
+ CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
+static unsigned long hardlockup_allcpu_dumped;
+/*
+ * We may not want to enable hard lockup detection by default in all cases,
+ * for example when running the kernel as a guest on a hypervisor. In these
+ * cases this function can be called to disable hard lockup detection. This
+ * function should only be executed once by the boot processor before the
+ * kernel command line parameters are parsed, because otherwise it is not
+ * possible to override this in hardlockup_panic_setup().
+ */
+void hardlockup_detector_disable(void)
+{
+ watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
+}
+
+static int __init hardlockup_panic_setup(char *str)
+{
+ if (!strncmp(str, "panic", 5))
+ hardlockup_panic = 1;
+ else if (!strncmp(str, "nopanic", 7))
+ hardlockup_panic = 0;
+ else if (!strncmp(str, "0", 1))
+ watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
+ else if (!strncmp(str, "1", 1))
+ watchdog_enabled |= NMI_WATCHDOG_ENABLED;
+ return 1;
+}
+__setup("nmi_watchdog=", hardlockup_panic_setup);
+
+void touch_nmi_watchdog(void)
+{
+ /*
+ * Using __raw here because some code paths have
+ * preemption enabled. If preemption is enabled
+ * then interrupts should be enabled too, in which
+ * case we shouldn't have to worry about the watchdog
+ * going off.
+ */
+ raw_cpu_write(watchdog_nmi_touch, true);
+ touch_softlockup_watchdog();
+}
+EXPORT_SYMBOL(touch_nmi_watchdog);
+
+static struct perf_event_attr wd_hw_attr = {
+ .type = PERF_TYPE_HARDWARE,
+ .config = PERF_COUNT_HW_CPU_CYCLES,
+ .size = sizeof(struct perf_event_attr),
+ .pinned = 1,
+ .disabled = 1,
+};
+
+/* Callback function for perf event subsystem */
+static void watchdog_overflow_callback(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ /* Ensure the watchdog never gets throttled */
+ event->hw.interrupts = 0;
+
+ if (__this_cpu_read(watchdog_nmi_touch) == true) {
+ __this_cpu_write(watchdog_nmi_touch, false);
+ return;
+ }
+
+ /* check for a hardlockup
+ * This is done by making sure our timer interrupt
+ * is incrementing. The timer interrupt should have
+ * fired multiple times before we overflow'd. If it hasn't
+ * then this is a good indication the cpu is stuck
+ */
+ if (is_hardlockup()) {
+ int this_cpu = smp_processor_id();
+ struct pt_regs *regs = get_irq_regs();
+
+ /* only print hardlockups once */
+ if (__this_cpu_read(hard_watchdog_warn) == true)
+ return;
+
+ pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
+ print_modules();
+ print_irqtrace_events(current);
+ if (regs)
+ show_regs(regs);
+ else
+ dump_stack();
+
+ /*
+ * Perform all-CPU dump only once to avoid multiple hardlockups
+ * generating interleaving traces
+ */
+ if (sysctl_hardlockup_all_cpu_backtrace &&
+ !test_and_set_bit(0, &hardlockup_allcpu_dumped))
+ trigger_allbutself_cpu_backtrace();
+
+ if (hardlockup_panic)
+ nmi_panic(regs, "Hard LOCKUP");
+
+ __this_cpu_write(hard_watchdog_warn, true);
+ return;
+ }
+
+ __this_cpu_write(hard_watchdog_warn, false);
+}
+
+/*
+ * People like the simple clean cpu node info on boot.
+ * Reduce the watchdog noise by only printing messages
+ * that are different from what cpu0 displayed.
+ */
+static unsigned long cpu0_err;
+
+int watchdog_nmi_enable(unsigned int cpu)
+{
+ struct perf_event_attr *wd_attr;
+ struct perf_event *event = per_cpu(watchdog_ev, cpu);
+
+ /* nothing to do if the hard lockup detector is disabled */
+ if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
+ goto out;
+
+ /* is it already setup and enabled? */
+ if (event && event->state > PERF_EVENT_STATE_OFF)
+ goto out;
+
+ /* it is setup but not enabled */
+ if (event != NULL)
+ goto out_enable;
+
+ wd_attr = &wd_hw_attr;
+ wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
+
+ /* Try to register using hardware perf events */
+ event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
+
+ /* save cpu0 error for future comparision */
+ if (cpu == 0 && IS_ERR(event))
+ cpu0_err = PTR_ERR(event);
+
+ if (!IS_ERR(event)) {
+ /* only print for cpu0 or different than cpu0 */
+ if (cpu == 0 || cpu0_err)
+ pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
+ goto out_save;
+ }
+
+ /*
+ * Disable the hard lockup detector if _any_ CPU fails to set up
+ * set up the hardware perf event. The watchdog() function checks
+ * the NMI_WATCHDOG_ENABLED bit periodically.
+ *
+ * The barriers are for syncing up watchdog_enabled across all the
+ * cpus, as clear_bit() does not use barriers.
+ */
+ smp_mb__before_atomic();
+ clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
+ smp_mb__after_atomic();
+
+ /* skip displaying the same error again */
+ if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
+ return PTR_ERR(event);
+
+ /* vary the KERN level based on the returned errno */
+ if (PTR_ERR(event) == -EOPNOTSUPP)
+ pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
+ else if (PTR_ERR(event) == -ENOENT)
+ pr_warn("disabled (cpu%i): hardware events not enabled\n",
+ cpu);
+ else
+ pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
+ cpu, PTR_ERR(event));
+
+ pr_info("Shutting down hard lockup detector on all cpus\n");
+
+ return PTR_ERR(event);
+
+ /* success path */
+out_save:
+ per_cpu(watchdog_ev, cpu) = event;
+out_enable:
+ perf_event_enable(per_cpu(watchdog_ev, cpu));
+out:
+ return 0;
+}
+
+void watchdog_nmi_disable(unsigned int cpu)
+{
+ struct perf_event *event = per_cpu(watchdog_ev, cpu);
+
+ if (event) {
+ perf_event_disable(event);
+ per_cpu(watchdog_ev, cpu) = NULL;
+
+ /* should be in cleanup, but blocks oprofile */
+ perf_event_release_kernel(event);
+ }
+ if (cpu == 0) {
+ /* watchdog_nmi_enable() expects this to be zero initially. */
+ cpu0_err = 0;
+ }
+}
--
1.7.1
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 <[email protected]>
---
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
On Tue, Nov 01, 2016 at 02:13:43PM -0700, Babu Moger wrote:
> This is an attempt to cleanup watchdog handlers. Right now,
> kernel/watchdog.c implements both softlockup and hardlockup detectors.
> Softlockup code is generic. Hardlockup code is arch specific. Some
> architectures don't use hardlockup detectors. They use their own watchdog
> detectors. To make both these combination work, we have numerous #ifdefs
> in kernel/watchdog.c.
>
> We are trying here to make these handlers independent of each other.
> Also provide an interface for architectures to implement their own
> handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
> as weak such that architectures can override its definitions.
>
> Thanks to Don Zickus for his suggestions.
> Here are our previous discussions
> http://www.spinics.net/lists/sparclinux/msg16543.html
> http://www.spinics.net/lists/sparclinux/msg16441.html
>
Hi Babu,
Thanks for the patches. It passes my panic/reboot testing. The patches
look good for now. Though this change has me thinking about other cleanup
changes I can make on top of this. But I am going to hold off for now until
we are sure nothing really broke. As this should be a straight forward
split.
The only odd thing for me is I am having trouble disabling
CONFIG_HARDLOCKUP_DETECTOR. For some reason def_bool y, is forcing the
option on despite my repeated attempts to disable it. I had to rename the
option to do some test compiling and verify it doesn't regress when
disabled. Probably my environment..
Thanks for the work Babu!
Acked-by: Don Zickus <[email protected]>
> v2:
> Addressed few comments from Don Zickus.
> 1. Took care of bisectability issue. Previous patch2 is patch1 now.
> Combined patch 1 and 3. Patch 4 is now patch 3.
> 2. Added pr_fmt back in watchdog_hld.c
> 3. Tweaked the file headers for watchdog.c and watchdog_hld.c.
>
> 4. Took care of couple of config compile issues.
>
> drivers/edac/edac_device.o:(.discard+0x0): multiple definition of `__pcpu_unique_hrtimer_interrupts'
> drivers/edac/edac_mc.o:(.discard+0x0): first defined here
> This was a problem with uni processor config. Moved the definition of hrtimer_interrupts and
> is_hardlockup into watchdog.c as softlockup code does most of the work here.
> is_hardlockup kind of generic most part.
>
> kernel/built-in.o: In function `watchdog_overflow_callback':
> watchdog_hld.c:(.text+0x56940): undefined reference to `sysctl_hardlockup_all_cpu_backtrace'
> Moved this definition to nmi.h.
>
> v1:
> Initial version
> Babu Moger (3):
> watchdog: Move shared definitions to nmi.h
> watchdog: Move hardlockup detector to separate file
> sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable
>
> arch/sparc/kernel/nmi.c | 44 ++++++++-
> include/linux/nmi.h | 24 ++++
> kernel/Makefile | 1 +
> kernel/watchdog.c | 270 +++--------------------------------------------
> kernel/watchdog_hld.c | 227 +++++++++++++++++++++++++++++++++++++++
> 5 files changed, 310 insertions(+), 256 deletions(-)
> create mode 100644 kernel/watchdog_hld.c
>
On 11/4/2016 11:25 AM, Don Zickus wrote:
> On Tue, Nov 01, 2016 at 02:13:43PM -0700, Babu Moger wrote:
>> This is an attempt to cleanup watchdog handlers. Right now,
>> kernel/watchdog.c implements both softlockup and hardlockup detectors.
>> Softlockup code is generic. Hardlockup code is arch specific. Some
>> architectures don't use hardlockup detectors. They use their own watchdog
>> detectors. To make both these combination work, we have numerous #ifdefs
>> in kernel/watchdog.c.
>>
>> We are trying here to make these handlers independent of each other.
>> Also provide an interface for architectures to implement their own
>> handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
>> as weak such that architectures can override its definitions.
>>
>> Thanks to Don Zickus for his suggestions.
>> Here are our previous discussions
>> http://www.spinics.net/lists/sparclinux/msg16543.html
>> http://www.spinics.net/lists/sparclinux/msg16441.html
>>
> Hi Babu,
>
> Thanks for the patches. It passes my panic/reboot testing. The patches
> look good for now. Though this change has me thinking about other cleanup
> changes I can make on top of this. But I am going to hold off for now until
> we are sure nothing really broke. As this should be a straight forward
> split.
>
> The only odd thing for me is I am having trouble disabling
> CONFIG_HARDLOCKUP_DETECTOR. For some reason def_bool y, is forcing the
> option on despite my repeated attempts to disable it. I had to rename the
> option to do some test compiling and verify it doesn't regress when
> disabled. Probably my environment..
Don, You are welcome. Thanks for your feedback to resolve this.
>
> Thanks for the work Babu!
>
> Acked-by: Don Zickus <[email protected]>
>
>
>> v2:
>> Addressed few comments from Don Zickus.
>> 1. Took care of bisectability issue. Previous patch2 is patch1 now.
>> Combined patch 1 and 3. Patch 4 is now patch 3.
>> 2. Added pr_fmt back in watchdog_hld.c
>> 3. Tweaked the file headers for watchdog.c and watchdog_hld.c.
>>
>> 4. Took care of couple of config compile issues.
>>
>> drivers/edac/edac_device.o:(.discard+0x0): multiple definition of `__pcpu_unique_hrtimer_interrupts'
>> drivers/edac/edac_mc.o:(.discard+0x0): first defined here
>> This was a problem with uni processor config. Moved the definition of hrtimer_interrupts and
>> is_hardlockup into watchdog.c as softlockup code does most of the work here.
>> is_hardlockup kind of generic most part.
>>
>> kernel/built-in.o: In function `watchdog_overflow_callback':
>> watchdog_hld.c:(.text+0x56940): undefined reference to `sysctl_hardlockup_all_cpu_backtrace'
>> Moved this definition to nmi.h.
>>
>> v1:
>> Initial version
>> Babu Moger (3):
>> watchdog: Move shared definitions to nmi.h
>> watchdog: Move hardlockup detector to separate file
>> sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable
>>
>> arch/sparc/kernel/nmi.c | 44 ++++++++-
>> include/linux/nmi.h | 24 ++++
>> kernel/Makefile | 1 +
>> kernel/watchdog.c | 270 +++--------------------------------------------
>> kernel/watchdog_hld.c | 227 +++++++++++++++++++++++++++++++++++++++
>> 5 files changed, 310 insertions(+), 256 deletions(-)
>> create mode 100644 kernel/watchdog_hld.c
>>
From: Babu Moger <[email protected]>
Date: Tue, 1 Nov 2016 14:13:43 -0700
> This is an attempt to cleanup watchdog handlers. Right now,
> kernel/watchdog.c implements both softlockup and hardlockup detectors.
> Softlockup code is generic. Hardlockup code is arch specific. Some
> architectures don't use hardlockup detectors. They use their own watchdog
> detectors. To make both these combination work, we have numerous #ifdefs
> in kernel/watchdog.c.
>
> We are trying here to make these handlers independent of each other.
> Also provide an interface for architectures to implement their own
> handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
> as weak such that architectures can override its definitions.
>
> Thanks to Don Zickus for his suggestions.
> Here are our previous discussions
> http://www.spinics.net/lists/sparclinux/msg16543.html
> http://www.spinics.net/lists/sparclinux/msg16441.html
This touches a bunch of generic code, only the third patch is sparc
specific.
Anyways have any plans to merge this via another tree or should I
take it via sparc? If I take it via sparc I want some ACKs.
Thanks.
From: Babu Moger <[email protected]>
Date: Mon, 21 Nov 2016 14:25:50 -0600
> Hi Dave,
>
> On 11/21/2016 12:42 PM, David Miller wrote:
>> From: Babu Moger <[email protected]>
>> Date: Tue, 1 Nov 2016 14:13:43 -0700
>>
>>> This is an attempt to cleanup watchdog handlers. Right now,
>>> kernel/watchdog.c implements both softlockup and hardlockup detectors.
>>> Softlockup code is generic. Hardlockup code is arch specific. Some
>>> architectures don't use hardlockup detectors. They use their own
>>> watchdog
>>> detectors. To make both these combination work, we have numerous
>>> #ifdefs
>>> in kernel/watchdog.c.
>>>
>>> We are trying here to make these handlers independent of each other.
>>> Also provide an interface for architectures to implement their own
>>> handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
>>> as weak such that architectures can override its definitions.
>>>
>>> Thanks to Don Zickus for his suggestions.
>>> Here are our previous discussions
>>> http://www.spinics.net/lists/sparclinux/msg16543.html
>>> http://www.spinics.net/lists/sparclinux/msg16441.html
>> This touches a bunch of generic code, only the third patch is sparc
>> specific.
>>
>> Anyways have any plans to merge this via another tree or should I
>> take it via sparc? If I take it via sparc I want some ACKs.
>
> Not sure how these things work. I have got following responses from
> Andrew Morton earlier.
Ok, if Andrew put it in his tree I'll just assume these changes will
take that path.