forked from analogdevicesinc/linux
-
Notifications
You must be signed in to change notification settings - Fork 3
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
This patch adds a new kernel debug feature: CONFIG_DETECT_SOFTLOCKUP. When enabled then per-CPU watchdog threads are started, which try to run once per second. If they get delayed for more than 10 seconds then a callback from the timer interrupt detects this condition and prints out a warning message and a stack dump (once per lockup incident). The feature is otherwise non-intrusive, it doesnt try to unlock the box in any way, it only gets the debug info out, automatically, and on all CPUs affected by the lockup. Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Nishanth Aravamudan <[email protected]> Signed-Off-By: Matthias Urlichs <[email protected]> Signed-off-by: Richard Purdie <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
- Loading branch information
Ingo Molnar
authored and
Linus Torvalds
committed
Sep 7, 2005
1 parent
4732efb
commit 8446f1d
Showing
12 changed files
with
201 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,151 @@ | ||
/* | ||
* Detect Soft Lockups | ||
* | ||
* started by Ingo Molnar, (C) 2005, Red Hat | ||
* | ||
* this code detects soft lockups: incidents in where on a CPU | ||
* the kernel does not reschedule for 10 seconds or more. | ||
*/ | ||
|
||
#include <linux/mm.h> | ||
#include <linux/cpu.h> | ||
#include <linux/init.h> | ||
#include <linux/delay.h> | ||
#include <linux/kthread.h> | ||
#include <linux/notifier.h> | ||
#include <linux/module.h> | ||
|
||
static DEFINE_SPINLOCK(print_lock); | ||
|
||
static DEFINE_PER_CPU(unsigned long, timestamp) = 0; | ||
static DEFINE_PER_CPU(unsigned long, print_timestamp) = 0; | ||
static DEFINE_PER_CPU(struct task_struct *, watchdog_task); | ||
|
||
static int did_panic = 0; | ||
static int softlock_panic(struct notifier_block *this, unsigned long event, | ||
void *ptr) | ||
{ | ||
did_panic = 1; | ||
|
||
return NOTIFY_DONE; | ||
} | ||
|
||
static struct notifier_block panic_block = { | ||
.notifier_call = softlock_panic, | ||
}; | ||
|
||
void touch_softlockup_watchdog(void) | ||
{ | ||
per_cpu(timestamp, raw_smp_processor_id()) = jiffies; | ||
} | ||
EXPORT_SYMBOL(touch_softlockup_watchdog); | ||
|
||
/* | ||
* This callback runs from the timer interrupt, and checks | ||
* whether the watchdog thread has hung or not: | ||
*/ | ||
void softlockup_tick(struct pt_regs *regs) | ||
{ | ||
int this_cpu = smp_processor_id(); | ||
unsigned long timestamp = per_cpu(timestamp, this_cpu); | ||
|
||
if (per_cpu(print_timestamp, this_cpu) == timestamp) | ||
return; | ||
|
||
/* Do not cause a second panic when there already was one */ | ||
if (did_panic) | ||
return; | ||
|
||
if (time_after(jiffies, timestamp + 10*HZ)) { | ||
per_cpu(print_timestamp, this_cpu) = timestamp; | ||
|
||
spin_lock(&print_lock); | ||
printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n", | ||
this_cpu); | ||
show_regs(regs); | ||
spin_unlock(&print_lock); | ||
} | ||
} | ||
|
||
/* | ||
* The watchdog thread - runs every second and touches the timestamp. | ||
*/ | ||
static int watchdog(void * __bind_cpu) | ||
{ | ||
struct sched_param param = { .sched_priority = 99 }; | ||
int this_cpu = (long) __bind_cpu; | ||
|
||
printk("softlockup thread %d started up.\n", this_cpu); | ||
|
||
sched_setscheduler(current, SCHED_FIFO, ¶m); | ||
current->flags |= PF_NOFREEZE; | ||
|
||
set_current_state(TASK_INTERRUPTIBLE); | ||
|
||
/* | ||
* Run briefly once per second - if this gets delayed for | ||
* more than 10 seconds then the debug-printout triggers | ||
* in softlockup_tick(): | ||
*/ | ||
while (!kthread_should_stop()) { | ||
msleep_interruptible(1000); | ||
touch_softlockup_watchdog(); | ||
} | ||
__set_current_state(TASK_RUNNING); | ||
|
||
return 0; | ||
} | ||
|
||
/* | ||
* Create/destroy watchdog threads as CPUs come and go: | ||
*/ | ||
static int __devinit | ||
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) | ||
{ | ||
int hotcpu = (unsigned long)hcpu; | ||
struct task_struct *p; | ||
|
||
switch (action) { | ||
case CPU_UP_PREPARE: | ||
BUG_ON(per_cpu(watchdog_task, hotcpu)); | ||
p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu); | ||
if (IS_ERR(p)) { | ||
printk("watchdog for %i failed\n", hotcpu); | ||
return NOTIFY_BAD; | ||
} | ||
per_cpu(watchdog_task, hotcpu) = p; | ||
kthread_bind(p, hotcpu); | ||
break; | ||
case CPU_ONLINE: | ||
|
||
wake_up_process(per_cpu(watchdog_task, hotcpu)); | ||
break; | ||
#ifdef CONFIG_HOTPLUG_CPU | ||
case CPU_UP_CANCELED: | ||
/* Unbind so it can run. Fall thru. */ | ||
kthread_bind(per_cpu(watchdog_task, hotcpu), smp_processor_id()); | ||
case CPU_DEAD: | ||
p = per_cpu(watchdog_task, hotcpu); | ||
per_cpu(watchdog_task, hotcpu) = NULL; | ||
kthread_stop(p); | ||
break; | ||
#endif /* CONFIG_HOTPLUG_CPU */ | ||
} | ||
return NOTIFY_OK; | ||
} | ||
|
||
static struct notifier_block __devinitdata cpu_nfb = { | ||
.notifier_call = cpu_callback | ||
}; | ||
|
||
__init void spawn_softlockup_task(void) | ||
{ | ||
void *cpu = (void *)(long)smp_processor_id(); | ||
|
||
cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); | ||
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); | ||
register_cpu_notifier(&cpu_nfb); | ||
|
||
notifier_chain_register(&panic_notifier_list, &panic_block); | ||
} | ||
|
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters