From: Andrew Morton <akpm@osdl.org>

Prevent infinite looping when handling a WARN() (I think)

Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/powerpc/kernel/traps.c |    2 +-
 include/linux/bug.h         |   11 ++++++++---
 lib/bug.c                   |   18 +++++++++---------
 3 files changed, 18 insertions(+), 13 deletions(-)

diff -puN arch/powerpc/kernel/traps.c~use-generic-bug-for-powerpc-fix-2 arch/powerpc/kernel/traps.c
--- a/arch/powerpc/kernel/traps.c~use-generic-bug-for-powerpc-fix-2
+++ a/arch/powerpc/kernel/traps.c
@@ -779,7 +779,7 @@ void __kprobes program_check_exception(s
 			return;
 
 		if (!(regs->msr & MSR_PR) &&  /* not user-mode */
-		    report_bug(regs->nip)) {
+		    report_bug(regs->nip) == BUG_TRAP_TYPE_WARN) {
 			regs->nip += 4;
 			return;
 		}
diff -puN include/linux/bug.h~use-generic-bug-for-powerpc-fix-2 include/linux/bug.h
--- a/include/linux/bug.h~use-generic-bug-for-powerpc-fix-2
+++ a/include/linux/bug.h
@@ -6,12 +6,17 @@
 #ifdef CONFIG_GENERIC_BUG
 #include <linux/module.h>
 
+enum bug_trap_type {
+	BUG_TRAP_TYPE_NONE = 0,
+	BUG_TRAP_TYPE_WARN = 1,
+	BUG_TRAP_TYPE_BUG = 2,
+};
+
 const struct bug_entry *find_bug(unsigned long bugaddr);
 
-int report_bug(unsigned long bug_addr);
+enum bug_trap_type report_bug(unsigned long bug_addr);
 
-int  module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
-			 struct module *);
+int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *, struct module *);
 void module_bug_cleanup(struct module *);
 
 /* These are defined by the architecture */
diff -puN lib/bug.c~use-generic-bug-for-powerpc-fix-2 lib/bug.c
--- a/lib/bug.c~use-generic-bug-for-powerpc-fix-2
+++ a/lib/bug.c
@@ -75,18 +75,18 @@ const struct bug_entry *find_bug(unsigne
 	return module_find_bug(bugaddr);
 }
 
-int report_bug(unsigned long bugaddr)
+enum bug_trap_type report_bug(unsigned long bugaddr)
 {
 	const struct bug_entry *bug;
 	const char *file, *function;
 	unsigned line;
 
 	if (!is_valid_bugaddr(bugaddr))
-		return 0;
+		return BUG_TRAP_TYPE_NONE;
 
 	bug = find_bug(bugaddr);
 	if (!bug)
-		return 0;
+		return BUG_TRAP_TYPE_NONE;
 
 	printk(KERN_EMERG "------------[ cut here ]------------\n");
 
@@ -100,19 +100,19 @@ int report_bug(unsigned long bugaddr)
 			printk(KERN_ERR "Badness in %s at %s:%u\n",
 			       function, file, line);
 		else
-			printk(KERN_ERR "Badness at %p [verbose debug info unavailable]\n",
-			       (void *)bugaddr);
+			printk(KERN_ERR "Badness at %p [verbose debug info "
+				"unavailable]\n", (void *)bugaddr);
 
 		dump_stack();
-		return 1;
+		return BUG_TRAP_TYPE_WARN;
 	}
 
 	if (file)
 		printk(KERN_CRIT "kernel BUG in %s at %s:%u!\n",
 		       function, file, line);
 	else
-		printk(KERN_EMERG "Kernel BUG at %p [verbose debug info unavailable]\n",
-		       (void *)bugaddr);
+		printk(KERN_EMERG "Kernel BUG at %p [verbose debug info "
+				"unavailable]\n", (void *)bugaddr);
 
-	return 0;
+	return BUG_TRAP_TYPE_BUG;
 }
_