2 files changed, 62 insertions, 17 deletions

diff --git a/kernel/backtracetest.c b/kernel/backtracetest.c
index d1a7605c5b8f..a5e026bc45c4 100644
--- a/kernel/backtracetest.c
+++ b/kernel/backtracetest.c
@@ -10,30 +10,73 @@
  * of the License.
  */
 
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/sched.h>
-#include <linux/delay.h>
+#include <linux/stacktrace.h>
+
+static void backtrace_test_normal(void)
+{
+	printk("Testing a backtrace from process context.\n");
+	printk("The following trace is a kernel self test and not a bug!\n");
 
-static struct timer_list backtrace_timer;
+	dump_stack();
+}
 
-static void backtrace_test_timer(unsigned long data)
+static DECLARE_COMPLETION(backtrace_work);
+
+static void backtrace_test_irq_callback(unsigned long data)
+{
+	dump_stack();
+	complete(&backtrace_work);
+}
+
+static DECLARE_TASKLET(backtrace_tasklet, &backtrace_test_irq_callback, 0);
+
+static void backtrace_test_irq(void)
 {
 	printk("Testing a backtrace from irq context.\n");
 	printk("The following trace is a kernel self test and not a bug!\n");
-	dump_stack();
+
+	init_completion(&backtrace_work);
+	tasklet_schedule(&backtrace_tasklet);
+	wait_for_completion(&backtrace_work);
+}
+
+#ifdef CONFIG_STACKTRACE
+static void backtrace_test_saved(void)
+{
+	struct stack_trace trace;
+	unsigned long entries[8];
+
+	printk("Testing a saved backtrace.\n");
+	printk("The following trace is a kernel self test and not a bug!\n");
+
+	trace.nr_entries = 0;
+	trace.max_entries = ARRAY_SIZE(entries);
+	trace.entries = entries;
+	trace.skip = 0;
+
+	save_stack_trace(&trace);
+	print_stack_trace(&trace, 0);
+}
+#else
+static void backtrace_test_saved(void)
+{
+	printk("Saved backtrace test skipped.\n");
 }
+#endif
+
 static int backtrace_regression_test(void)
 {
 	printk("====[ backtrace testing ]===========\n");
-	printk("Testing a backtrace from process context.\n");
-	printk("The following trace is a kernel self test and not a bug!\n");
-	dump_stack();
 
-	init_timer(&backtrace_timer);
-	backtrace_timer.function = backtrace_test_timer;
-	mod_timer(&backtrace_timer, jiffies + 10);
+	backtrace_test_normal();
+	backtrace_test_irq();
+	backtrace_test_saved();
 
-	msleep(10);
 	printk("====[ end of backtrace testing ]====\n");
 	return 0;
 }
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index b71816e47a30..94b527ef1d1e 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -6,19 +6,21 @@
  *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  */
 #include <linux/sched.h>
+#include <linux/module.h>
 #include <linux/kallsyms.h>
 #include <linux/stacktrace.h>
 
 void print_stack_trace(struct stack_trace *trace, int spaces)
 {
-	int i, j;
+	int i;
 
-	for (i = 0; i < trace->nr_entries; i++) {
-		unsigned long ip = trace->entries[i];
+	if (WARN_ON(!trace->entries))
+		return;
 
-		for (j = 0; j < spaces + 1; j++)
-			printk(" ");
-		print_ip_sym(ip);
+	for (i = 0; i < trace->nr_entries; i++) {
+		printk("%*c", 1 + spaces, ' ');
+		print_ip_sym(trace->entries[i]);
 	}
 }
+EXPORT_SYMBOL_GPL(print_stack_trace);