[PATCH] kselftest: dt: Stop relying on dirname to improve performance

[Nícolas F. R. A. Prado]

When walking directory trees, instead of looking for specific files and
running dirname to get the parent folder, traverse all folders and
ignore the ones not containing the desired files. This avoids the need
to call dirname inside the loop, which gives a big performance boost,
approximately halving run time: Running locally on a
mt8192-asurada-spherion, which reports 160 test cases, has gone from
5.5s to 2.9s, while running remotely with an nfsroot has gone from
13.5s to 5.5s.

This change has a side-effect, which is that the root DT node now
also shows in the output, even though it isn't expected to bind to a
driver. However there shouldn't be a matching driver for the board
compatible, so the end result will be just an extra skipped test:

ok 1 / # SKIP

Reported-by: Mark Brown <broonie@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/310391e8-fdf2-4c2f-a680-7744eb685177@xxxxxxxxxxxxx
Fixes: 14571ab1ad21 ("kselftest: Add new test for detecting unprobed Devicetree devices")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>

---

 tools/testing/selftests/dt/test_unprobed_devices.sh | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/dt/test_unprobed_devices.sh b/tools/testing/selftests/dt/test_unprobed_devices.sh
index b07af2a4c4de..7fae90293a9d 100755
--- a/tools/testing/selftests/dt/test_unprobed_devices.sh
+++ b/tools/testing/selftests/dt/test_unprobed_devices.sh
@@ -33,8 +33,8 @@ if [[ ! -d "${PDT}" ]]; then
 fi
 
 nodes_compatible=$(
-	for node_compat in $(find ${PDT} -name compatible); do
-		node=$(dirname "${node_compat}")
+	for node in $(find ${PDT} -type d); do
+		[ ! -f "${node}"/compatible ] && continue
 		# Check if node is available
 		if [[ -e "${node}"/status ]]; then
 			status=$(tr -d '\000' < "${node}"/status)
@@ -46,10 +46,11 @@ nodes_compatible=$(
 
 nodes_dev_bound=$(
 	IFS=$'\n'
-	for uevent in $(find /sys/devices -name uevent); do
-		if [[ -d "$(dirname "${uevent}")"/driver ]]; then
-			grep '^OF_FULLNAME=' "${uevent}" | sed -e 's|OF_FULLNAME=||'
-		fi
+	for dev_dir in $(find /sys/devices -type d); do
+		[ ! -f "${dev_dir}"/uevent ] && continue
+		[ ! -d "${dev_dir}"/driver ] && continue
+
+		grep '^OF_FULLNAME=' "${dev_dir}"/uevent | sed -e 's|OF_FULLNAME=||'
 	done
 	)
 
-- 
2.43.0