Re: [PATCH v5 6/7] kallsyms: add /proc/kallmodsyms

Re: [PATCH v5 6/7] kallsyms: add /proc/kallmodsyms

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 2884 bytes --]

Hi Nick,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.15-rc7]
[cannot apply to jeyu/modules-next masahiroy/kconfig next-20211027]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Nick-Alcock/kbuild-bring-back-tristate-conf/20211028-024948
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2f111a6fd5b5297b4e92f53798ca086f7c7d33a4
config: hexagon-randconfig-r041-20211027 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 5db7568a6a1fcb408eb8988abdaff2a225a8eb72)
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
        # https://github.com/0day-ci/linux/commit/3e2ed787d495a82851cad4d99a369524140966ae
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Nick-Alcock/kbuild-bring-back-tristate-conf/20211028-024948
        git checkout 3e2ed787d495a82851cad4d99a369524140966ae
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/kallsyms.c:645:12: warning: no previous prototype for function 'arch_get_kallsym' [-Wmissing-prototypes]
   int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
              ^
   kernel/kallsyms.c:645:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
   ^
   static 
   kernel/kallsyms.c:1054:30: warning: unused variable 'kallsyms_proc_ops' [-Wunused-const-variable]
   static const struct proc_ops kallsyms_proc_ops = {
                                ^
>> kernel/kallsyms.c:1062:30: warning: unused variable 'kallmodsyms_proc_ops' [-Wunused-const-variable]
   static const struct proc_ops kallmodsyms_proc_ops = {
                                ^
   3 warnings generated.


vim +/kallmodsyms_proc_ops +1062 kernel/kallsyms.c

  1060	
  1061	#ifdef CONFIG_KALLMODSYMS
> 1062	static const struct proc_ops kallmodsyms_proc_ops = {
  1063		.proc_open	= kallmodsyms_open,
  1064		.proc_read	= seq_read,
  1065		.proc_lseek	= seq_lseek,
  1066		.proc_release	= seq_release_private,
  1067	};
  1068	#endif
  1069	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 27340 bytes --]

Re: [PATCH v5 6/7] kallsyms: add /proc/kallmodsyms

[Nick Alcock]

For reference, and to be maximally pedantic:

On 28 Oct 2021, kernel test robot said:

> Hi Nick,
>
> Thank you for the patch! Perhaps something to improve:

Nope! This is a (very small) flaw in the !CONFIG_PROC_FS case in
include/linux/proc_fs.h. (I don't think one can seriously call it a
*bug*, as such.)

It's not a problem in this patch.

> config: hexagon-randconfig-r041-20211027 (attached as .config)

This config includes: 

# CONFIG_PROC_FS is not set

> All warnings (new ones prefixed by >>):
[unrelated warnings snipped]
>    static 
>    kernel/kallsyms.c:1054:30: warning: unused variable 'kallsyms_proc_ops' [-Wunused-const-variable]
>    static const struct proc_ops kallsyms_proc_ops = {
>                                 ^

This warning already existed (and doubtless countless others just like
it all over the tree in this configuration).  This is because
proc_create(), in the !CONFIG_PROC_FS case, is a #define that just does
nothing: so the compiler can see that none of its args are used, and
will complain about those that have no other references. The proc_ops is
almost certainly going to be one such.

The new warning is just the same:

>>> kernel/kallsyms.c:1062:30: warning: unused variable 'kallmodsyms_proc_ops' [-Wunused-const-variable]
>    static const struct proc_ops kallmodsyms_proc_ops = {
>                                 ^
>    3 warnings generated.

The kallmodsyms_proc_ops is obviously doing the same thing as
kallsyms_proc_ops (because it has to), so it gets the same warning.

Short of wrapping every single declaration of a proc_ops structure, and
every call to proc_create, in #ifdef CONFIG_PROC_FS (which is obviously
gross and exactly the thing the macro in proc_fs.h is intended to
avoid), there is no way of fixing this warning on its own: it must be
fixed in proc_fs.h. (Perhaps by making a bunch of those macros into
functions with __attribute__((__unused__)) attached to appropriate
args.)

-- 
NULL && (void)