linux-kernel - Re: [PATCH] init: move THIS_MODULE from <linux/export.h> to <linux/init.h>

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Message-ID: <ZXDDx4/g4Le38oEh@windriver.com>
Date:   Wed, 6 Dec 2023 13:56:07 -0500
From:   Paul Gortmaker <paul.gortmaker@...driver.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-modules@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] init: move THIS_MODULE from <linux/export.h> to
 <linux/init.h>

[Re: [PATCH] init: move THIS_MODULE from <linux/export.h> to <linux/init.h>] On 03/12/2023 (Sun 19:06) Masahiro Yamada wrote:

> On Sun, Nov 26, 2023 at 4:19???PM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > Commit f50169324df4 ("module.h: split out the EXPORT_SYMBOL into
> > export.h") appropriately separated EXPORT_SYMBOL into <linux/export.h>
> > because modules and EXPORT_SYMBOL are orthogonal; modules are symbol
> > consumers, while EXPORT_SYMBOL are used by symbol providers, which
> > may not be necessarily a module.
> >
> > However, that commit also relocated THIS_MODULE. As explained in the
> > commit description, the intention was to define THIS_MODULE in a
> > lightweight header, but I do not believe <linux/export.h> was the
> > suitable location because EXPORT_SYMBOL and THIS_MODULE are unrelated.
> >
> > Move it to another lightweight header, <linux/init.h>. The reason for
> > choosing <linux/init.h> is to make <linux/moduleparam.h> self-contained
> > without relying on <linux/linkage.h> incorrectly including
> > <linux/export.h>.
> >
> > With this adjustment, the role of <linux/export.h> becomes clearer as
> > it only defines EXPORT_SYMBOL.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > ---
> 
> 
> Applied to kbuild.
> 
> I did not get any report from the 0day bot so far,
> but I hope it will get a little more compile tests
> before getting into linux-next.

Haven't touched that kind of header shuffle for over 10 years?

But yeah, it is near impossible to not trip over some implicit header
inclusion somewhere in some driver or a less common arch and hence break
the build at least once when doing this kind of stuff.

Paul.
--

> 
> 
> 
> >
> >  include/linux/export.h | 18 ------------------
> >  include/linux/init.h   |  7 +++++++
> >  2 files changed, 7 insertions(+), 18 deletions(-)
> >
> > diff --git a/include/linux/export.h b/include/linux/export.h
> > index 9911508a9604..0bbd02fd351d 100644
> > --- a/include/linux/export.h
> > +++ b/include/linux/export.h
> > @@ -6,15 +6,6 @@
> >  #include <linux/linkage.h>
> >  #include <linux/stringify.h>
> >
> > -/*
> > - * Export symbols from the kernel to modules.  Forked from module.h
> > - * to reduce the amount of pointless cruft we feed to gcc when only
> > - * exporting a simple symbol or two.
> > - *
> > - * Try not to add #includes here.  It slows compilation and makes kernel
> > - * hackers place grumpy comments in header files.
> > - */
> > -
> >  /*
> >   * This comment block is used by fixdep. Please do not remove.
> >   *
> > @@ -23,15 +14,6 @@
> >   * side effect of the *.o build rule.
> >   */
> >
> > -#ifndef __ASSEMBLY__
> > -#ifdef MODULE
> > -extern struct module __this_module;
> > -#define THIS_MODULE (&__this_module)
> > -#else
> > -#define THIS_MODULE ((struct module *)0)
> > -#endif
> > -#endif /* __ASSEMBLY__ */
> > -
> >  #ifdef CONFIG_64BIT
> >  #define __EXPORT_SYMBOL_REF(sym)                       \
> >         .balign 8                               ASM_NL  \
> > diff --git a/include/linux/init.h b/include/linux/init.h
> > index 01b52c9c7526..3fa3f6241350 100644
> > --- a/include/linux/init.h
> > +++ b/include/linux/init.h
> > @@ -179,6 +179,13 @@ extern void (*late_time_init)(void);
> >
> >  extern bool initcall_debug;
> >
> > +#ifdef MODULE
> > +extern struct module __this_module;
> > +#define THIS_MODULE (&__this_module)
> > +#else
> > +#define THIS_MODULE ((struct module *)0)
> > +#endif
> > +
> >  #endif
> >
> >  #ifndef MODULE
> > --
> > 2.40.1
> >
> 
> 
> -- 
> Best Regards
> Masahiro Yamada