Merge branch 'core/stacktrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core/stacktrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  generic-ipi: powerpc/generic-ipi tree build failure
  stacktrace: fix build failure on sparc64
  stacktrace: export save_stack_trace[_tsk]
  stacktrace: fix modular build, export print_stack_trace and save_stack_trace
  backtrace: replace timer with tasklet + completions
  stacktrace: add saved stack traces to backtrace self-test
  stacktrace: print_stack_trace() cleanup
  debugging: make stacktrace independent from DEBUG_KERNEL
  stacktrace: don't crash on invalid stack trace structs

arch/arm/kernel/stacktrace.c

@@ -92,4 +92,5 @@ void save_stack_trace(struct stack_trace *trace)
 {
 	save_stack_trace_tsk(current, trace);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 #endif

arch/avr32/kernel/stacktrace.c

@@ -51,3 +51,4 @@ void save_stack_trace(struct stack_trace *trace)
 		fp = frame->fp;
 	}
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);

arch/mips/kernel/stacktrace.c

@@ -73,3 +73,4 @@ void save_stack_trace(struct stack_trace *trace)
 	prepare_frametrace(regs);
 	save_context_stack(trace, regs);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);

arch/powerpc/kernel/stacktrace.c

@@ -12,6 +12,7 @@
 
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
+#include <linux/module.h>
 #include <asm/ptrace.h>
 
 /*
@@ -44,3 +45,4 @@ void save_stack_trace(struct stack_trace *trace)
 		sp = newsp;
 	}
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);

arch/s390/kernel/stacktrace.c

@@ -81,6 +81,7 @@ void save_stack_trace(struct stack_trace *trace)
 			   S390_lowcore.thread_info,
 			   S390_lowcore.thread_info + THREAD_SIZE, 1);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
@@ -93,3 +94,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 	if (trace->nr_entries < trace->max_entries)
 		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

arch/sh/kernel/stacktrace.c

@@ -34,3 +34,4 @@ void save_stack_trace(struct stack_trace *trace)
 		}
 	}
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);

arch/sparc64/kernel/stacktrace.c

@@ -1,6 +1,7 @@
 #include <linux/sched.h>
 #include <linux/stacktrace.h>
 #include <linux/thread_info.h>
+#include <linux/module.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
@@ -47,3 +48,4 @@ void save_stack_trace(struct stack_trace *trace)
 			trace->entries[trace->nr_entries++] = pc;
 	} while (trace->nr_entries < trace->max_entries);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);

arch/x86/kernel/stacktrace.c

@@ -74,6 +74,7 @@ void save_stack_trace(struct stack_trace *trace)
 	if (trace->nr_entries < trace->max_entries)
 		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
@@ -81,3 +82,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 	if (trace->nr_entries < trace->max_entries)
 		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

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 struct timer_list backtrace_timer;
+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 void backtrace_test_timer(unsigned long data)
+	dump_stack();
+}
+
+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;
 }

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;
+
+	if (WARN_ON(!trace->entries))
+		return;
 
 	for (i = 0; i < trace->nr_entries; i++) {
-		unsigned long ip = trace->entries[i];
-
-		for (j = 0; j < spaces + 1; j++)
-			printk(" ");
-		print_ip_sym(ip);
+		printk("%*c", 1 + spaces, ' ');
+		print_ip_sym(trace->entries[i]);
 	}
 }
+EXPORT_SYMBOL_GPL(print_stack_trace);
 

lib/Kconfig.debug

@@ -419,7 +419,6 @@ config DEBUG_LOCKING_API_SELFTESTS
 
 config STACKTRACE
 	bool
-	depends on DEBUG_KERNEL
 	depends on STACKTRACE_SUPPORT
 
 config DEBUG_KOBJECT
@@ -563,6 +562,9 @@ config BACKTRACE_SELF_TEST
 	  for distributions or general kernels, but only for kernel
 	  developers working on architecture code.
 
+	  Note that if you want to also test saved backtraces, you will
+	  have to enable STACKTRACE as well.
+
 	  Say N if you are unsure.
 
 config LKDTM