Re: [PATCH] init.h: discard exitcall symbols early

[Arnd Bergmann]

On Tue, Mar 31, 2026, at 16:56, Petr Mladek wrote:
> Adding module loader maintainers into Cc to make them aware of this
> change.
>
> On Tue 2026-03-31 16:28:38, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>> 
>> Any __exitcall() and built-in module_exit() handler is marked as __used,
>> which leads to the code being included in the object file and later
>> discarded at link time.
>
> Is this safe for dynamically loaded modules?
>
> Honestly, I am not sure what is the exact efect of this change.
> The dynamically loadded modules just came to my mind...

In a loadable module, using __exitcall() directly already discards
the function at link time, so there is no difference from built-in
code. Actually using __exitcall() here is a mistake regardless
of my patch.

Using module_exit() in a loadable module still behaves as before,
this uses a different macro, which already has __maybe_unused:

#define module_exit(exitfn)                                     \
        static inline exitcall_t __maybe_unused __exittest(void)                \
        { return exitfn; }                                      \
        void cleanup_module(void) __copy(exitfn)                \
                __attribute__((alias(#exitfn)));                \
        ___ADDRESSABLE(cleanup_module, __exitdata);

so this is also unchanged.

      Arnd