linux-kernel - kernel/module/main.c:4515:14: warning: variable 'exit' set but not used

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Message-ID: <202206071718.QNuYKpUb-lkp@intel.com>
Date:   Tue, 7 Jun 2022 17:53:12 +0800
From:   kernel test robot <lkp@...el.com>
To:     Aaron Tomlin <atomlin@...hat.com>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Luis Chamberlain <mcgrof@...nel.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Subject: kernel/module/main.c:4515:14: warning: variable 'exit' set but not
 used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   e71e60cd74df9386c3f684c54888f2367050b831
commit: cfc1d277891eb499b3b5354df33b30f598683e90 module: Move all into module/
date:   9 weeks ago
config: arm64-buildonly-randconfig-r011-20220607 (https://download.01.org/0day-ci/archive/20220607/202206071718.QNuYKpUb-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project b92436efcb7813fc481b30f2593a4907568d917a)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cfc1d277891eb499b3b5354df33b30f598683e90
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout cfc1d277891eb499b3b5354df33b30f598683e90
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash kernel/module/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> kernel/module/main.c:4515:14: warning: variable 'exit' set but not used [-Wunused-but-set-variable]
           exitcall_t *exit;
                       ^
   kernel/module/main.c:4802:6: warning: no previous prototype for function 'module_layout' [-Wmissing-prototypes]
   void module_layout(struct module *mod,
        ^
   kernel/module/main.c:4802:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void module_layout(struct module *mod,
   ^
   static 
   2 warnings generated.


vim +/exit +4515 kernel/module/main.c

^1da177e4c3f41 kernel/module.c Linus Torvalds 2005-04-16  4510  
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4511  static void cfi_init(struct module *mod)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4512  {
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4513  #ifdef CONFIG_CFI_CLANG
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4514  	initcall_t *init;
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08 @4515  	exitcall_t *exit;
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4516  
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4517  	rcu_read_lock_sched();
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4518  	mod->cfi_check = (cfi_check_fn)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4519  		find_kallsyms_symbol_value(mod, "__cfi_check");
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4520  	init = (initcall_t *)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4521  		find_kallsyms_symbol_value(mod, "__cfi_jt_init_module");
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4522  	exit = (exitcall_t *)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4523  		find_kallsyms_symbol_value(mod, "__cfi_jt_cleanup_module");
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4524  	rcu_read_unlock_sched();
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4525  
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4526  	/* Fix init/exit functions to point to the CFI jump table */
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4527  	if (init)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4528  		mod->init = *init;
0d67e332e6df72 kernel/module.c Arnd Bergmann  2021-09-27  4529  #ifdef CONFIG_MODULE_UNLOAD
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4530  	if (exit)
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4531  		mod->exit = *exit;
0d67e332e6df72 kernel/module.c Arnd Bergmann  2021-09-27  4532  #endif
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4533  
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4534  	cfi_module_add(mod, module_addr_min);
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4535  #endif
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4536  }
cf68fffb66d60d kernel/module.c Sami Tolvanen  2021-04-08  4537  

:::::: The code at line 4515 was first introduced by commit
:::::: cf68fffb66d60d96209446bfc4a15291dc5a5d41 add support for Clang CFI

:::::: TO: Sami Tolvanen <samitolvanen@...gle.com>
:::::: CC: Kees Cook <keescook@...omium.org>

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp