Re: [00/10]: Netfilter Update

[Patrick McHardy <kaber@trash.net>]

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David S. Miller wrote:
>>      [NETFILTER]: Fix undefined references to get_h225_addr
> 
> 
> I never in a million years would have thought that exporting
> a symbol to modules would work if the symbol was declared
> static :-)  But come to think of it, I see nothing that prevents
> this.
> 
> I wonder if this could be prevented somehow using so me construct
> in the module symbol export macros?

I was surprised too. Looking at the gcc-builtins, there seems to
be no way to determine if a function is static. But this small
hack appears to work. It adds a non-static forward declaration of
the exported function to the function body, causing a warning
if the function was declared static.

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diff --git a/include/linux/module.h b/include/linux/module.h
index 70bd843..f8eec37 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -183,6 +183,7 @@ void *__symbol_get_gpl(const char *symbo
 
 /* For every exported symbol, place a struct in the __ksymtab section */
 #define __EXPORT_SYMBOL(sym, sec)				\
+	typeof(sym) sym;					\
 	__CRC_SYMBOL(sym, sec)					\
 	static const char __kstrtab_##sym[]			\
 	__attribute__((section("__ksymtab_strings")))		\