The result of running my find_badref_configs.sh script, which looks for CONFIG_* variables being tested, but apparently not defined in any Kconfig* file.

#!/bin/sh

SCAN_DIR=${1-*}

CVARS=$(find ${SCAN_DIR} -name "*.[ch]" |    \
        grep -v "mach-types.h" |        \
        xargs ifnames |                 \
        grep "^CONFIG_" |               \
        cut -d' ' -f1 |                 \
        sed "s/^CONFIG_//" |            \
        sed "s/_MODULE$//" |            \
        sort -u)

ALL_KCONFIG_FILES=$(find . -name "Kconfig*")

#
#  Scan the entire tree, just to see what turns up.
#

for cv in ${CVARS} ; do
        # echo "Testing ${cv} ..."
        egrep -q "^[[:space:]]*config[[:space:]]+${cv}\b" ${ALL_KCONFIG_FILES} ||
        grep -q "^menuconfig *${cv}$" ${ALL_KCONFIG_FILES} ||
        egrep -qr "^[[:space:]]*#[[:space:]]*define[[:space:]]+CONFIG_${cv}\b" * || {
                echo ">>>>> ${cv}"
                grep -rwn "CONFIG_${cv}" * | grep -v defconfig
                grep -rwn "${cv}" * | grep -v defconfig
        }
done 2> /dev/null