Re: [PATCH] Detect and warn on atomic_inc/atomic_dec wrapping around

Andrew Morton
2009-05-01T05:16:50Z

On Thu, 30 Apr 2009 22:06:48 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri, 1 May 2009 10:27:46 +0530 Nikanth Karthikesan <knikanth@novell.com> wrote:
>
> > I tried with linux/bug.h. But it creates a cyclic dependency. linux/bug.h
> > pulls in linux/module.h => linux/spinlock.h => asm/spinlock.h (which uses
> > atomic_inc) => asm/atomic.h,.
>
> And why on earth does bug.h need module.h?
>
> int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
> struct module *);
>
> The ever-smelly Elf_Ehdr and Elf_Shdr.
>
> Probably the module_bug_finalize/module_bug_cleanup declarations and
> definitions should be in module.h.
>

I queued the below. I _guess_ it's an improvement - bug.h is a quite
low-level thing.

I don't yet know what will explode as a result.

From: Andrew Morton <akpm@linux-foundation.org>

They're in linux/bug.h at present, which causes include order tangles. In
particular, linux/bug.h cannot be used by linux/atomic.h because,
according to Nikanth:

linux/bug.h pulls in linux/module.h => linux/spinlock.h => asm/spinlock.h
(which uses atomic_inc) => asm/atomic.h.

bug.h is a pretty low-level thing and module.h is a higher-level thing,
IMO.

Cc: Nikanth Karthikesan <knikanth@novell.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

include/linux/bug.h | 12 ------------
include/linux/module.h | 17 +++++++++++++++++
2 files changed, 17 insertions(+), 12 deletions(-)

diff -puN include/linux/bug.h~headers-move-module_bug_finalize-module_bug_cleanup-definitions-into-moduleh include/linux/bug.h
--- a/include/linux/bug.h~headers-move-module_bug_finalize-module_bug_cleanup-definitions-into-moduleh
+++ a/include/linux/bug.h
@@ -1,7 +1,6 @@
#ifndef _LINUX_BUG_H
#define _LINUX_BUG_H

-#include <linux/module.h>
#include <asm/bug.h>

enum bug_trap_type {
@@ -24,10 +23,6 @@ const struct bug_entry *find_bug(unsigne

enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);

-int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
- struct module *);
-void module_bug_cleanup(struct module *);
-
/* These are defined by the architecture */
int is_valid_bugaddr(unsigned long addr);

@@ -38,13 +33,6 @@ static inline enum bug_trap_type report_
{
return BUG_TRAP_TYPE_BUG;
}
-static inline int module_bug_finalize(const Elf_Ehdr *hdr,
- const Elf_Shdr *sechdrs,
- struct module *mod)
-{
- return 0;
-}
-static inline void module_bug_cleanup(struct module *mod) {}

#endif /* CONFIG_GENERIC_BUG */
#endif /* _LINUX_BUG_H */
diff -puN include/linux/module.h~headers-move-module_bug_finalize-module_bug_cleanup-definitions-into-moduleh include/linux/module.h
--- a/include/linux/module.h~headers-move-module_bug_finalize-module_bug_cleanup-definitions-into-moduleh
+++ a/include/linux/module.h
@@ -696,4 +696,21 @@ static inline void module_remove_modinfo

#define __MODULE_STRING(x) __stringify(x)

+
+#ifdef CONFIG_GENERIC_BUG
+int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
+ struct module *);
+void module_bug_cleanup(struct module *);
+
+#else /* !CONFIG_GENERIC_BUG */
+
+static inline int module_bug_finalize(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs,
+ struct module *mod)
+{
+ return 0;
+}
+static inline void module_bug_cleanup(struct module *mod) {}
+#endif /* CONFIG_GENERIC_BUG */
+
#endif /* _LINUX_MODULE_H */
_