[PATCH] add dump_stack(): cross-arch backtrace

From Christoph Hellwig, also present in 2.4.

Create an arch-independent `dump_stack()' function.  So we don't need to do

#ifdef CONFIG_X86
	show_stack(0);		/* No prototype in scope! */
#endif

any more.

The whole dump_stack() implementation is delegated to the architecture.
If it doesn't provide one, there is a default do-nothing library
function.

arch/alpha/kernel/traps.c

@@ -171,6 +171,11 @@ void show_stack(unsigned long *sp)
 	dik_show_trace(sp);
 }
 
+void dump_stack(void)
+{
+	show_stack(NULL);
+}
+
 void
 die_if_kernel(char * str, struct pt_regs *regs, long err, unsigned long *r9_15)
 {

arch/cris/kernel/traps.c

@@ -230,8 +230,12 @@ watchdog_bite_hook(struct pt_regs *regs)
 #endif	
 }
 
-/* This is normally the 'Oops' routine */
+void dump_stack(void)
+{
+	show_stack(NULL);
+}
 
+/* This is normally the 'Oops' routine */
 void 
 die_if_kernel(const char * str, struct pt_regs * regs, long err)
 {

arch/i386/kernel/traps.c

@@ -189,6 +189,14 @@ void show_stack(unsigned long * esp)
 	show_trace(esp);
 }
 
+/*
+ * The architecture-independent dump_stack generator
+ */
+void dump_stack(void)
+{
+	show_stack(0);
+}
+
 void show_registers(struct pt_regs *regs)
 {
 	int i;

fs/buffer.c

@@ -61,10 +61,8 @@ void __buffer_error(char *file, int line)
 		return;
 	enough++;
 	printk("buffer layer error at %s:%d\n", file, line);
-#ifdef CONFIG_X86
 	printk("Pass this trace through ksymoops for reporting\n");
-	show_stack(0);
-#endif
+	dump_stack();
 }
 EXPORT_SYMBOL(__buffer_error);
 

include/linux/kernel.h

@@ -96,6 +96,8 @@ extern const char *print_tainted(void);
 #define TAINT_FORCED_MODULE		(1<<1)
 #define TAINT_UNSAFE_SMP		(1<<2)
 
+extern void dump_stack(void);
+
 #if DEBUG
 #define pr_debug(fmt,arg...) \
 	printk(KERN_DEBUG fmt,##arg)

kernel/ksyms.c

@@ -605,3 +605,6 @@ EXPORT_SYMBOL(pidhash);
 #if defined(CONFIG_SMP) && defined(__GENERIC_PER_CPU)
 EXPORT_SYMBOL(__per_cpu_offset);
 #endif
+
+/* debug */
+EXPORT_SYMBOL(dump_stack);

lib/Makefile

@@ -12,7 +12,7 @@ export-objs := cmdline.o dec_and_lock.o rwsem-spinlock.o rwsem.o \
 	       crc32.o rbtree.o radix-tree.o
 
 obj-y := errno.o ctype.o string.o vsprintf.o brlock.o cmdline.o \
-	 bust_spinlocks.o rbtree.o radix-tree.o
+	 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o
 
 obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
 obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o

lib/dump_stack.c

+/*
+ * Provide a default dump_stack() function for architectures
+ * which don't implement their own.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+void dump_stack(void)
+{
+	printk(KERN_NOTICE
+		"This architecture does not implement dump_stack()\n");
+}