Hi grantseltzer, Thank you for the patch! Yet something to improve: [auto build test ERROR on bpf-next/master] url: https://github.com/intel-lab-lkp/linux/commits/grantseltzer/Add-error-returns-to-two-API-functions/20220420-000638 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: s390-randconfig-r023-20220420 (https://download.01.org/0day-ci/archive/20220420/202204201650.TNnvoXPQ-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project bac6cd5bf85669e3376610cfc4c4f9ca015e7b9b) 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 s390 cross compiling tool for clang build # apt-get install binutils-s390x-linux-gnu # https://github.com/intel-lab-lkp/linux/commit/55a52c4514ab205b288dce0a609d5d7bab485813 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review grantseltzer/Add-error-returns-to-two-API-functions/20220420-000638 git checkout 55a52c4514ab205b288dce0a609d5d7bab485813 # 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=s390 prepare If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): >> libbpf.c:8570:1: error: non-void function does not return a value in all control paths [-Werror,-Wreturn-type] } ^ 1 error generated. make[5]: *** [tools/build/Makefile.build:96: tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf.o] Error 1 make[5]: *** Waiting for unfinished jobs.... make[4]: *** [Makefile:157: tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf-in.o] Error 2 make[3]: *** [Makefile:55: tools/bpf/resolve_btfids//libbpf/libbpf.a] Error 2 make[2]: *** [Makefile:72: bpf/resolve_btfids] Error 2 make[1]: *** [Makefile:1337: tools/bpf/resolve_btfids] Error 2 In file included from arch/s390/kernel/asm-offsets.c:11: In file included from include/linux/kvm_host.h:41: In file included from include/linux/kvm_para.h:5: In file included from include/uapi/linux/kvm_para.h:37: In file included from arch/s390/include/asm/kvm_para.h:25: In file included from arch/s390/include/asm/diag.h:12: In file included from include/linux/if_ether.h:19: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:10: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __raw_readb(PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu' #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x)) ^ include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16' #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) ^ In file included from arch/s390/kernel/asm-offsets.c:11: In file included from include/linux/kvm_host.h:41: In file included from include/linux/kvm_para.h:5: In file included from include/uapi/linux/kvm_para.h:37: In file included from arch/s390/include/asm/kvm_para.h:25: In file included from arch/s390/include/asm/diag.h:12: In file included from include/linux/if_ether.h:19: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:10: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:35:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32' #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x)) ^ In file included from arch/s390/kernel/asm-offsets.c:11: In file included from include/linux/kvm_host.h:41: In file included from include/linux/kvm_para.h:5: In file included from include/uapi/linux/kvm_para.h:37: In file included from arch/s390/include/asm/kvm_para.h:25: In file included from arch/s390/include/asm/diag.h:12: In file included from include/linux/if_ether.h:19: In file included from include/linux/skbuff.h:31: In file included from include/linux/dma-mapping.h:10: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writeb(value, PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ 12 warnings generated. make[1]: Target 'prepare' not remade because of errors. make: *** [Makefile:219: __sub-make] Error 2 make: Target 'prepare' not remade because of errors. -- 0-DAY CI Kernel Test Service https://01.org/lkp