[kbuild-all] Re: arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot'

Le 12/05/2021 à 11:36, Christophe Leroy a écrit : > > > Le 11/05/2021 à 20:46, Nathan Chancellor a écrit : >> On 5/11/2021 9:47 AM, Christophe Leroy wrote: >>> Hi All, >>> >>> Le 11/05/2021 à 18:30, kernel test robot a écrit : >>>> Hi Christophe, >>>> >>>> First bad commit (maybe != root cause): >>>> >>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >>>> head:   1140ab592e2ebf8153d2b322604031a8868ce7a5 >>>> commit: eacf4c0202654adfa94bbb17b5c5c77c0be14af8 powerpc: Enable OPTPROBES on PPC32 > > Ok, the problem appears on PPC32 with that patch, but it must have been there on PPC64 since the > implementation of optprobes with commit 51c9c0843993 ("powerpc/kprobes: Implement Optprobes") > > >>>> date:   3 weeks ago >>>> config: powerpc-randconfig-r033-20210511 (attached as .config) >>>> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project >>>> a0fed635fe1701470062495a6ffee1c608f3f1bc) >>> >>> A clang issue ? >>> >>> >>>> 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 powerpc cross compiling tool for clang build >>>>          # apt-get install binutils-powerpc-linux-gnu >>>>          # >>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... >>>> >>>>          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >>>>          git fetch --no-tags linus master >>>>          git checkout eacf4c0202654adfa94bbb17b5c5c77c0be14af8 >>>>          # save the attached .config to linux build tree >>>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=powerpc >>>> >>>> If you fix the issue, kindly add following tag as appropriate >>>> Reported-by: kernel test robot <lkp(a)intel.com&gt; >>>> >>>> All errors (new ones prefixed by >>): >>>> >>>>>> arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot' >>>>>> [-Werror,-Wunused-function] >>>>     DEFINE_INSN_CACHE_OPS(ppc_optinsn); >>>>     ^ >>>>     include/linux/kprobes.h:306:20: note: expanded from macro 'DEFINE_INSN_CACHE_OPS' >>>>     static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \ >>> >>> That's a 'static inline', shouldn't generate an 'unused function' warning. >> This is a W=1 build, which means that "inline" does not silence unused function warnings with >> clang because of commit 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions >> for W=1 build"). > > Ok, I didn't know that. After looking at it in more details, I don't really know what should be done to avoid that.

This unused function is defined as part of DEFINE_INSN_CACHE_OPS(ppc_optinsn). The code uses other items defined by macro DEFINE_INSN_CACHE_OPS, so it cannot be removed. Solution could be to hide that in a .h, but is that worth it ?