reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        git remote add openeuler https://gitee.com/openeuler/kernel.git
        git fetch --no-tags openeuler openEuler-1.0-LTS
        git checkout 7ad207616673722d5cf52c18d9464e0d3184ffc9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 SHELL=/bin/bash net/ipv4/