Merge tag 'tracefs-v6.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracefs fixes from Steven Rostedt:
 "Fix tracefs mount options.

  Commit 78ff64081949 ("vfs: Convert tracefs to use the new mount API")
  broke the gid setting when set by fstab or other mount utility. It is
  ignored when it is set. Fix the code so that it recognises the option
  again and will honor the settings on mount at boot up.

  Update the internal documentation and create a selftest to make sure
  it doesn't break again in the future"

* tag 'tracefs-v6.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/selftests: Add tracefs mount options test
  tracing: Document tracefs gid mount option
  tracing: Fix tracefs mount options

3 files changed, 129 insertions, 13 deletions

diff --git a/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc b/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc
new file mode 100644
index 000000000000..35e8d47d6072
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc
@@ -0,0 +1,101 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Test tracefs GID mount option
+# requires: "[gid=<gid>]":README
+
+fail() {
+	local msg="$1"
+
+	echo "FAILED: $msg"
+	exit_fail
+}
+
+find_alternate_gid() {
+	local original_gid="$1"
+	tac /etc/group | grep -v ":$original_gid:" | head -1 | cut -d: -f3
+}
+
+mount_tracefs_with_options() {
+	local mount_point="$1"
+	local options="$2"
+
+	mount -t tracefs -o "$options" nodev "$mount_point"
+
+	setup
+}
+
+unmount_tracefs() {
+	local mount_point="$1"
+
+	# Need to make sure the mount isn't busy so that we can umount it
+	(cd $mount_point; finish_ftrace;)
+
+	cleanup
+}
+
+create_instance() {
+	local mount_point="$1"
+	local instance="$mount_point/instances/$(mktemp -u test-XXXXXX)"
+
+	mkdir "$instance"
+	echo "$instance"
+}
+
+remove_instance() {
+	local instance="$1"
+
+	rmdir "$instance"
+}
+
+check_gid() {
+	local mount_point="$1"
+	local expected_gid="$2"
+
+	echo "Checking permission group ..."
+
+	cd "$mount_point"
+
+	for file in "." "events" "events/sched" "events/sched/sched_switch" "events/sched/sched_switch/enable"; do
+		local gid=`stat -c "%g" $file`
+		if [ "$gid" -ne "$expected_gid" ]; then
+			cd - # Return to the previous working directory (tracefs root)
+			fail "$(realpath $file): Expected group $expected_gid; Got group $gid"
+		fi
+	done
+
+	cd - # Return to the previous working directory (tracefs root)
+}
+
+test_gid_mount_option() {
+	local mount_point=$(get_mount_point)
+	local mount_options=$(get_mnt_options "$mount_point")
+	local original_group=$(stat -c "%g" .)
+	local other_group=$(find_alternate_gid "$original_group")
+
+	# Set up mount options with new GID for testing
+	local new_options=`echo "$mount_options" | sed -e "s/gid=[0-9]*/gid=$other_group/"`
+	if [ "$new_options" = "$mount_options" ]; then
+		new_options="$mount_options,gid=$other_group"
+		mount_options="$mount_options,gid=$original_group"
+	fi
+
+	# Unmount existing tracefs instance and mount with new GID
+	unmount_tracefs "$mount_point"
+	mount_tracefs_with_options "$mount_point" "$new_options"
+
+	check_gid "$mount_point" "$other_group"
+
+	# Check that files created after the mount inherit the GID
+	local instance=$(create_instance "$mount_point")
+	check_gid "$instance" "$other_group"
+	remove_instance "$instance"
+
+	# Unmount and remount with the original GID
+	unmount_tracefs "$mount_point"
+	mount_tracefs_with_options "$mount_point" "$mount_options"
+	check_gid "$mount_point" "$original_group"
+}
+
+test_gid_mount_option
+
+exit 0
diff --git a/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc b/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
index 094419e190c2..e71cc3ad0bdf 100644
--- a/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
+++ b/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
@@ -1,24 +1,14 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 # description: Test file and directory ownership changes for eventfs
+# requires: "[gid=<gid>]":README
 
 original_group=`stat -c "%g" .`
 original_owner=`stat -c "%u" .`
 
-mount_point=`stat -c '%m' .`
+local mount_point=$(get_mount_point)
 
-# If stat -c '%m' does not work (e.g. busybox) or failed, try to use the
-# current working directory (which should be a tracefs) as the mount point.
-if [ ! -d "$mount_point" ]; then
-	if mount | grep -qw $PWD ; then
-		mount_point=$PWD
-	else
-		# If PWD doesn't work, that is an environmental problem.
-		exit_unresolved
-	fi
-fi
-
-mount_options=`mount | grep "$mount_point" | sed -e 's/.*(\(.*\)).*/\1/'`
+mount_options=$(get_mnt_options "$mount_point")
 
 # find another owner and group that is not the original
 other_group=`tac /etc/group | grep -v ":$original_group:" | head -1 | cut -d: -f3`
diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index 779f3e62ec90..84d6a9c7ad67 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -193,3 +193,28 @@ ftrace_errlog_check() { # err-prefix command-with-error-pos-by-^ command-file
     # "  Command: " and "^\n" => 13
     test $(expr 13 + $pos) -eq $N
 }
+
+# Helper to get the tracefs mount point
+get_mount_point() {
+	local mount_point=`stat -c '%m' .`
+
+	# If stat -c '%m' does not work (e.g. busybox) or failed, try to use the
+	# current working directory (which should be a tracefs) as the mount point.
+	if [ ! -d "$mount_point" ]; then
+		if mount | grep -qw "$PWD"; then
+			mount_point=$PWD
+		else
+			# If PWD doesn't work, that is an environmental problem.
+			exit_unresolved
+		fi
+	fi
+	echo "$mount_point"
+}
+
+# Helper function to retrieve mount options for a given mount point
+get_mnt_options() {
+	local mnt_point="$1"
+	local opts=$(mount | grep -m1 "$mnt_point" | sed -e 's/.*(\(.*\)).*/\1/')
+
+	echo "$opts"
+}
\ No newline at end of file