Re: [PATCH] modules: Fix build error in moduleloader.h

From: Rusty Russell
Date: Mon Jul 07 2014 - 20:56:20 EST


Steven Rostedt <rostedt@xxxxxxxxxxx> writes:
> Fengguang Wu's build bot detected that if moduleloader.h is included in
> a C file (used by ftrace and kprobes to access module_alloc() when
> available), that it can fail to build if CONFIG_MODULES and
> CONFIG_MODULES_USE_ELF_REL is not defined.
>
> This is because there's a printk() that dereferences struct module to
> print the name of the module. But as struct module does not exist when
> CONFIG_MODULES is not defined we get this error:

First, we have module_name() for exactly this.

Second, there are two places like this: you hit
CONFIG_MODULES_USE_ELF_REL and not CONFIG_MODULES_USE_ELF_RELA.

(We could uninline them, and put them in module.c, but I think having
them in the header is nice and self-documenting.)

So does this work for you?

Thanks,
Rusty.
PS. Masami Hiramatsu, your review should have caught the second case,
at least :(

Subject: modules: Fix build error in moduleloader.h

Fengguang Wu's build bot detected that if moduleloader.h is included in
a C file (used by ftrace and kprobes to access module_alloc() when
available), that it can fail to build if CONFIG_MODULES and
CONFIG_MODULES_USE_ELF_REL is not defined.

This is because there's a printk() that dereferences struct module to
print the name of the module. But as struct module does not exist when
CONFIG_MODULES is not defined we get this error:

include/linux/moduleloader.h: In function 'apply_relocate':
>> include/linux/moduleloader.h:48:63: error: dereferencing pointer to
>> incomplete type
printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
^
Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Based-on-the-true-story-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index 560ca53a75fa..7eeb9bbfb816 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -45,7 +45,8 @@ static inline int apply_relocate(Elf_Shdr *sechdrs,
unsigned int relsec,
struct module *me)
{
- printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
+ printk(KERN_ERR "module %s: REL relocation unsupported\n",
+ module_name(me));
return -ENOEXEC;
}
#endif
@@ -67,7 +68,8 @@ static inline int apply_relocate_add(Elf_Shdr *sechdrs,
unsigned int relsec,
struct module *me)
{
- printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
+ printk(KERN_ERR "module %s: REL relocation unsupported\n",
+ module_name(me));
return -ENOEXEC;
}
#endif
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