reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/ceph/ceph-client/commit/8a1cb95e58001067ea33908f1762ca31d6f93b69
        git remote add ceph-client https://github.com/ceph/ceph-client.git
        git fetch --no-tags ceph-client binary_tracing
        git checkout 8a1cb95e58001067ea33908f1762ca31d6f93b69
        # 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/ceph/