[PATCH] lockdep: stacktrace subsystem, core

Framework to generate and save stacktraces quickly, without printing anything
to the console.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/stacktrace.h

@@ -0,0 +1,20 @@
+#ifndef __LINUX_STACKTRACE_H
+#define __LINUX_STACKTRACE_H
+
+#ifdef CONFIG_STACKTRACE
+struct stack_trace {
+	unsigned int nr_entries, max_entries;
+	unsigned long *entries;
+};
+
+extern void save_stack_trace(struct stack_trace *trace,
+			     struct task_struct *task, int all_contexts,
+			     unsigned int skip);
+
+extern void print_stack_trace(struct stack_trace *trace, int spaces);
+#else
+# define save_stack_trace(trace, task, all, skip)	do { } while (0)
+# define print_stack_trace(trace)			do { } while (0)
+#endif
+
+#endif

kernel/Makefile

@@ -10,6 +10,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
 	    hrtimer.o
 
+obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/
 obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
 obj-$(CONFIG_FUTEX) += futex.o

kernel/stacktrace.c

@@ -0,0 +1,24 @@
+/*
+ * kernel/stacktrace.c
+ *
+ * Stack trace management functions
+ *
+ *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ */
+#include <linux/sched.h>
+#include <linux/kallsyms.h>
+#include <linux/stacktrace.h>
+
+void print_stack_trace(struct stack_trace *trace, int spaces)
+{
+	int i, j;
+
+	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);
+	}
+}
+

lib/Kconfig.debug

@@ -107,7 +107,7 @@ config DEBUG_SLAB_LEAK
 
 config DEBUG_PREEMPT
 	bool "Debug preemptible kernel"
-	depends on DEBUG_KERNEL && PREEMPT
+	depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 	default y
 	help
 	  If you say Y here then the kernel will use a debug variant of the
@@ -149,6 +149,10 @@ config DEBUG_SPINLOCK_SLEEP
 	  If you say Y here, various routines which may sleep will become very
 	  noisy if they are called with a spinlock held.
 
+config STACKTRACE
+	bool
+	depends on STACKTRACE_SUPPORT
+
 config DEBUG_KOBJECT
 	bool "kobject debugging"
 	depends on DEBUG_KERNEL