Re: [PATCH] generic show_stack facility

[Andrew Morton]

David Mosberger wrote:
> 
> ..
>   Christoph> So your suggestion is to move the other architectures to
>   Christoph> the ia64 prototype or to not have an
>   Christoph> architecture-independand stack-traceback facility at all?
> 
> I haven't done such an investigation.  I believe the ia64 prototype is
> reasonable and probably implementable on all platforms that can unwind
> the stack in the first place, but before making a change to the stable
> kernel API, I'd think someone would have to investigate this a bit
> further.
> 

The way I ended up resolving these sorts of issues was to 
make the generic function

	void dump_stack(void);

under the (hopefully valid) assumption that all architectures
can somehow, in some manner, manage to spit out something
useful.

For a transitional/compatibility think, there's lib/dump_stack.c
which just prints "I'm broken".

Here's the diff.  Comments?

--- 2.4.19-pre4/include/linux/kernel.h~aa-094-dump_stack	Tue Mar 26 23:11:27 2002
+++ 2.4.19-pre4-akpm/include/linux/kernel.h	Tue Mar 26 23:11:27 2002
@@ -106,6 +106,8 @@ extern int oops_in_progress;		/* If set,
 extern int tainted;
 extern const char *print_tainted(void);
 
+extern void dump_stack(void);
+
 #if DEBUG
 #define pr_debug(fmt,arg...) \
 	printk(KERN_DEBUG fmt,##arg)
--- /dev/null	Thu Aug 30 13:30:55 2001
+++ 2.4.19-pre4-akpm/lib/dump_stack.c	Tue Mar 26 23:11:27 2002
@@ -0,0 +1,13 @@
+/*
+ * 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");
+}
--- 2.4.19-pre4/lib/Makefile~aa-094-dump_stack	Tue Mar 26 23:11:27 2002
+++ 2.4.19-pre4-akpm/lib/Makefile	Tue Mar 26 23:11:27 2002
@@ -10,7 +10,8 @@ L_TARGET := lib.a
 
 export-objs := cmdline.o dec_and_lock.o rwsem-spinlock.o rwsem.o rbtree.o
 
-obj-y := errno.o ctype.o string.o vsprintf.o brlock.o cmdline.o bust_spinlocks.o rbtree.o
+obj-y := errno.o ctype.o string.o vsprintf.o brlock.o cmdline.o \
+		bust_spinlocks.o rbtree.o dump_stack.o
 
 obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
 obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
--- 2.4.19-pre4/kernel/ksyms.c~aa-094-dump_stack	Tue Mar 26 23:11:27 2002
+++ 2.4.19-pre4-akpm/kernel/ksyms.c	Tue Mar 26 23:11:27 2002
@@ -560,3 +560,6 @@ EXPORT_SYMBOL(init_task_union);
 
 EXPORT_SYMBOL(tasklist_lock);
 EXPORT_SYMBOL(pidhash);
+
+/* debug */
+EXPORT_SYMBOL(dump_stack);
--- 2.4.19-pre4/arch/i386/kernel/traps.c~aa-094-dump_stack	Tue Mar 26 23:11:27 2002
+++ 2.4.19-pre4-akpm/arch/i386/kernel/traps.c	Tue Mar 26 23:11:27 2002
@@ -186,6 +186,14 @@ void show_stack(unsigned long * esp)
 	show_trace(esp);
 }
 
+/*
+ * The architecture-independent backtrace generator
+ */
+void dump_stack(void)
+{
+	show_stack(0);
+}
+
 void show_registers(struct pt_regs *regs)
 {
 	int i;