From 0075fa80305f3231a2d5df97b00d7f55a48ea27e Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 12 May 2008 21:20:47 +0200
Subject: ftrace: extend sysprof plugin

add per CPU hrtimers.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/trace/trace_sysprof.c | 67 +++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index 6c139bc1be7e..ba55b871b3d9 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -5,19 +5,76 @@
  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
  *
  */
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/debugfs.h>
 #include <linux/kallsyms.h>
+#include <linux/debugfs.h>
+#include <linux/hrtimer.h>
 #include <linux/uaccess.h>
-#include <linux/marker.h>
 #include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/fs.h>
 
 #include "trace.h"
 
 static struct trace_array	*ctx_trace;
 static int __read_mostly	tracer_enabled;
 
+static const unsigned long sample_period = 1000000;
+
+/*
+ * Per CPU hrtimers that do the profiling:
+ */
+static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer);
+
+static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
+{
+	/* trace here */
+	panic_timeout++;
+
+	hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
+
+	return HRTIMER_RESTART;
+}
+
+static void start_stack_timer(int cpu)
+{
+	struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
+
+	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer->function = stack_trace_timer_fn;
+	hrtimer->cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
+
+	hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL);
+}
+
+static void start_stack_timers(void)
+{
+	cpumask_t saved_mask = current->cpus_allowed;
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
+		start_stack_timer(cpu);
+		printk("started timer on cpu%d\n", cpu);
+	}
+	set_cpus_allowed_ptr(current, &saved_mask);
+}
+
+static void stop_stack_timer(int cpu)
+{
+	struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
+
+	hrtimer_cancel(hrtimer);
+	printk("cancelled timer on cpu%d\n", cpu);
+}
+
+static void stop_stack_timers(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		stop_stack_timer(cpu);
+}
+
 static notrace void stack_reset(struct trace_array *tr)
 {
 	int cpu;
@@ -31,11 +88,13 @@ static notrace void stack_reset(struct trace_array *tr)
 static notrace void start_stack_trace(struct trace_array *tr)
 {
 	stack_reset(tr);
+	start_stack_timers();
 	tracer_enabled = 1;
 }
 
 static notrace void stop_stack_trace(struct trace_array *tr)
 {
+	stop_stack_timers();
 	tracer_enabled = 0;
 }
 
-- 
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