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Subject[PATCH 5/9] x86: Move trigger_all_cpu_backtrace to its own die_notifier
Date
From: Don Zickus <dzickus@redhat.com>

As part of the transition of the nmi watchdog to something more
generic, the trigger_all_cpu_backtrace code is getting left behind.
Put it in its own die_notifier so it can still be used.

V2:
- use arch_spin_locks

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-6-git-send-email-dzickus@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
arch/x86/kernel/apic/hw_nmi.c | 65 ++++++++++++++++++++++++++++++++---------
1 files changed, 51 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 79425f9..8c3edfb 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -17,6 +17,10 @@
#include <linux/cpumask.h>
#include <linux/kernel_stat.h>
#include <asm/mce.h>
+#include <linux/kdebug.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+

#include <linux/nmi.h>
#include <linux/module.h>
@@ -54,20 +58,6 @@ int hw_nmi_is_cpu_stuck(struct pt_regs *regs)
unsigned int sum;
int cpu = smp_processor_id();

- /* FIXME: cheap hack for this check, probably should get its own
- * die_notifier handler
- */
- if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
- static DEFINE_SPINLOCK(lock); /* Serialise the printks */
-
- spin_lock(&lock);
- printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
- show_regs(regs);
- dump_stack();
- spin_unlock(&lock);
- cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
- }
-
/* if we are doing an mce, just assume the cpu is not stuck */
/* Could check oops_in_progress here too, but it's safer not to */
if (mce_in_progress())
@@ -109,6 +99,53 @@ void arch_trigger_all_cpu_backtrace(void)
mdelay(1);
}
}
+
+static int __kprobes
+arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
+ unsigned long cmd, void *__args)
+{
+ struct die_args *args = __args;
+ struct pt_regs *regs;
+ int cpu = smp_processor_id();
+
+ switch (cmd) {
+ case DIE_NMI:
+ case DIE_NMI_IPI:
+ break;
+
+ default:
+ return NOTIFY_DONE;
+ }
+
+ regs = args->regs;
+
+ if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
+ static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+ arch_spin_lock(&lock);
+ printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
+ show_regs(regs);
+ dump_stack();
+ arch_spin_unlock(&lock);
+ cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
+ return NOTIFY_STOP;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static __read_mostly struct notifier_block backtrace_notifier = {
+ .notifier_call = arch_trigger_all_cpu_backtrace_handler,
+ .next = NULL,
+ .priority = 1
+};
+
+static int __init register_trigger_all_cpu_backtrace(void)
+{
+ register_die_notifier(&backtrace_notifier);
+ return 0;
+}
+early_initcall(register_trigger_all_cpu_backtrace);
#endif

/* STUB calls to mimic old nmi_watchdog behaviour */
--
1.6.2.3


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