Re: [00/10]: Netfilter Update

[Patrick McHardy <kaber@trash.net>]

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Patrick McHardy wrote:
> 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.
> 
> 
> ------------------------------------------------------------------------
> 
> 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")))		\

That patch was broken, I only tested the case it should fail on, but
it also fails on symbols exported in different files. This one adds an
extern declaration instead, I think that should have the desired
effect.


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[MODULES]: Don't allow statically declared exports

Add an extern declaration for exported symbols to make the compiler warn
on symbols declared statically.

Signed-off-by: Patrick McHardy <kaber@trash.net>

---
commit 8648236083e488ff4fc279b66d63b1187e22e558
tree cba9ee372f1056c8cf63cdc6a37a6a761fa490c9
parent 8b21e6d05d6ac0aeb44f5866ab611e2709c2f08e
author Patrick McHardy <kaber@trash.net> Thu, 23 Mar 2006 05:07:39 +0100
committer Patrick McHardy <kaber@trash.net> Thu, 23 Mar 2006 05:07:39 +0100

 include/linux/module.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 70bd843..d956915 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)				\
+	extern typeof(sym) sym;					\
 	__CRC_SYMBOL(sym, sec)					\
 	static const char __kstrtab_##sym[]			\
 	__attribute__((section("__ksymtab_strings")))		\