Skip to content

Commit

Permalink
kernel/watchdog.c: move hardlockup detector to separate file
Browse files Browse the repository at this point in the history 
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.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Babu Moger <[email protected]>
Acked-by: Don Zickus <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Yaowei Bai <[email protected]>
Cc: Aaron Tomlin <[email protected]>
Cc: Ulrich Obergfell <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Hidehiro Kawai <[email protected]>
Cc: Josh Hunt <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
  • Loading branch information
@torvalds
Babu Moger authored and torvalds committed Dec 15, 2016
1 parent 249e52e commit 73ce051
Show file tree
Hide file tree
Showing 3 changed files with 239 additions and 230 deletions.
1 change: 1 addition & 0 deletions kernel/Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
241 changes: 11 additions & 230 deletions kernel/watchdog.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -80,50 +79,9 @@ static DEFINE_PER_CPU(bool, soft_watchdog_warn);
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;

Expand Down Expand Up @@ -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)
{
Expand All @@ -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)
{
Expand All @@ -293,77 +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();

/* 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);
Expand Down Expand Up @@ -556,109 +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,
Expand Down
Loading

0 comments on commit 73ce051

Please sign in to comment.