[PATCH v2 0/8] Remove child from struct ctl_table

[PATCH v2 0/8] Remove child from struct ctl_table

[Joel Granados]

This is part of the effort to remove the empty element of the ctl_table
structures (used to calculate size) and replace it with an ARRAY_SIZE call. By
replacing the child element in struct ctl_table with a flags element we make
sure that there are no forward recursions on child nodes and therefore set
ourselves up for just using an ARRAY_SIZE. We also added some self tests to
make sure that we do not break anything.

Patchset is separated in 4: parport fixes, selftests fixes, selftests additions and
replacement of child element. Tested everything with sysctl self tests and everything
seems "ok".

1. parport fixes: This is related to my previous series and it plugs a sysct
   table leak in the parport driver. @mcgrof: I'm just leaving this here so we
   don't have to retest the parport stuff

2. Selftests fixes: Remove the prefixed zeros when passing a awk field to the
   awk print command because it was causing $0009 to be interpreted as $0.
   Replaced continue with return in sysctl.sh(test_case) so the test actually
   gets skipped. The skip decision is now in sysctl.sh(skip_test).

3. Selftest additions: New test to confirm that unregister actually removes
   targets. New test to confirm that permanently empty targets are indeed
   created and that no other targets can be created "on top".

4. Replaced the child pointer in struct ctl_table with an enum which is used to
   differentiate between permanently empty targets and non-empty ones.

V2: Replaced the u8 flag with an enumeration.

Comments/feedback greatly appreciated

Best
Joel

Joel Granados (8):
  parport: plug a sysctl register leak
  test_sysctl: Fix test metadata getters
  test_sysctl: Group node sysctl test under one func
  test_sysctl: Add an unregister sysctl test
  test_sysctl: Add an option to prevent test skip
  test_sysclt: Test for registering a mount point
  sysctl: Remove debugging dump_stack
  sysctl: replace child with an enumeration

 drivers/parport/procfs.c                 |  23 ++---
 fs/proc/proc_sysctl.c                    |  82 ++++------------
 include/linux/sysctl.h                   |  14 ++-
 lib/test_sysctl.c                        |  91 ++++++++++++++++--
 tools/testing/selftests/sysctl/sysctl.sh | 115 +++++++++++++++++------
 5 files changed, 214 insertions(+), 111 deletions(-)

-- 
2.30.2

[PATCH v2 1/8] parport: plug a sysctl register leak

[Joel Granados]

parport registers two sysctl directories in the parport_proc_register
function but only one of them was getting unregistered in
parport_proc_unregister. Keep track of both sysctl table headers and
handle them together when (un)registering.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/parport/procfs.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/parport/procfs.c b/drivers/parport/procfs.c
index cbb1fb5127ce..0f2d2e1ee28e 100644
--- a/drivers/parport/procfs.c
+++ b/drivers/parport/procfs.c
@@ -257,14 +257,16 @@ PARPORT_MAX_SPINTIME_VALUE;
 
 
 struct parport_sysctl_table {
-	struct ctl_table_header *sysctl_header;
+	struct ctl_table_header *port_header;
+	struct ctl_table_header *devices_header;
 	struct ctl_table vars[12];
 	struct ctl_table device_dir[2];
 };
 
 static const struct parport_sysctl_table parport_sysctl_template = {
-	.sysctl_header = NULL,
-        {
+	.port_header = NULL,
+	.devices_header = NULL,
+	{
 		{
 			.procname	= "spintime",
 			.data		= NULL,
@@ -429,7 +431,6 @@ parport_default_sysctl_table = {
 int parport_proc_register(struct parport *port)
 {
 	struct parport_sysctl_table *t;
-	struct ctl_table_header *devices_h;
 	char *tmp_dir_path;
 	size_t tmp_path_len, port_name_len;
 	int bytes_written, i, err = 0;
@@ -464,8 +465,8 @@ int parport_proc_register(struct parport *port)
 		err = -ENOENT;
 		goto exit_free_tmp_dir_path;
 	}
-	devices_h = register_sysctl(tmp_dir_path, t->device_dir);
-	if (devices_h == NULL) {
+	t->devices_header = register_sysctl(tmp_dir_path, t->device_dir);
+	if (t->devices_header == NULL) {
 		err = -ENOENT;
 		goto  exit_free_tmp_dir_path;
 	}
@@ -478,8 +479,8 @@ int parport_proc_register(struct parport *port)
 		goto unregister_devices_h;
 	}
 
-	t->sysctl_header = register_sysctl(tmp_dir_path, t->vars);
-	if (t->sysctl_header == NULL) {
+	t->port_header = register_sysctl(tmp_dir_path, t->vars);
+	if (t->port_header == NULL) {
 		err = -ENOENT;
 		goto unregister_devices_h;
 	}
@@ -490,7 +491,7 @@ int parport_proc_register(struct parport *port)
 	return 0;
 
 unregister_devices_h:
-	unregister_sysctl_table(devices_h);
+	unregister_sysctl_table(t->devices_header);
 
 exit_free_tmp_dir_path:
 	kfree(tmp_dir_path);
@@ -505,7 +506,8 @@ int parport_proc_unregister(struct parport *port)
 	if (port->sysctl_table) {
 		struct parport_sysctl_table *t = port->sysctl_table;
 		port->sysctl_table = NULL;
-		unregister_sysctl_table(t->sysctl_header);
+		unregister_sysctl_table(t->devices_header);
+		unregister_sysctl_table(t->port_header);
 		kfree(t);
 	}
 	return 0;
-- 
2.30.2

[PATCH v2 2/8] test_sysctl: Fix test metadata getters

[Joel Granados]

The functions get_test_{count,enabled,target} use awk to get the N'th
field in the ALL_TESTS variable. A variable with leading zeros (e.g.
0009) is misinterpreted as an entire line instead of the N'th field.
Remove the leading zeros so this does not happen. We can now use the
helper in tests 6, 7 and 8.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 tools/testing/selftests/sysctl/sysctl.sh | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index bfc54b422f25..cb8f83dfe16b 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -730,7 +730,7 @@ sysctl_test_0005()
 
 sysctl_test_0006()
 {
-	TARGET="${SYSCTL}/bitmap_0001"
+	TARGET="${SYSCTL}/$(get_test_target 0006)"
 	reset_vals
 	ORIG=""
 	run_bitmaptest
@@ -738,7 +738,7 @@ sysctl_test_0006()
 
 sysctl_test_0007()
 {
-	TARGET="${SYSCTL}/boot_int"
+	TARGET="${SYSCTL}/$(get_test_target 0007)"
 	if [ ! -f $TARGET ]; then
 		echo "Skipping test for $TARGET as it is not present ..."
 		return $ksft_skip
@@ -778,7 +778,7 @@ sysctl_test_0007()
 
 sysctl_test_0008()
 {
-	TARGET="${SYSCTL}/match_int"
+	TARGET="${SYSCTL}/$(get_test_target 0008)"
 	if [ ! -f $TARGET ]; then
 		echo "Skipping test for $TARGET as it is not present ..."
 		return $ksft_skip
@@ -857,25 +857,32 @@ function test_num()
 		usage
 	fi
 }
+function remove_leading_zeros()
+{
+	echo $1 | sed 's/^0*//'
+}
 
 function get_test_count()
 {
 	test_num $1
-	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	awk_field=$(remove_leading_zeros $1)
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$awk_field'}')
 	echo ${TEST_DATA} | awk -F":" '{print $2}'
 }
 
 function get_test_enabled()
 {
 	test_num $1
-	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	awk_field=$(remove_leading_zeros $1)
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$awk_field'}')
 	echo ${TEST_DATA} | awk -F":" '{print $3}'
 }
 
 function get_test_target()
 {
 	test_num $1
-	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	awk_field=$(remove_leading_zeros $1)
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$awk_field'}')
 	echo ${TEST_DATA} | awk -F":" '{print $4}'
 }
 
-- 
2.30.2

[PATCH v2 3/8] test_sysctl: Group node sysctl test under one func

[Joel Granados]

Preparation commit to add a new type of test to test_sysctl.c. We
want to differentiate between node and (sub)directory tests.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 lib/test_sysctl.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/test_sysctl.c b/lib/test_sysctl.c
index e2a816d85ea2..0cf7c547d61a 100644
--- a/lib/test_sysctl.c
+++ b/lib/test_sysctl.c
@@ -126,9 +126,7 @@ static struct ctl_table test_table[] = {
 	{ }
 };
 
-static struct ctl_table_header *test_sysctl_header;
-
-static int __init test_sysctl_init(void)
+static void test_sysctl_calc_match_int_ok(void)
 {
 	int i;
 
@@ -153,7 +151,13 @@ static int __init test_sysctl_init(void)
 	for (i = 0; i < ARRAY_SIZE(match_int); i++)
 		if (match_int[i].defined != match_int[i].wanted)
 			match_int_ok = 0;
+}
 
+static struct ctl_table_header *test_sysctl_header;
+
+static int test_sysctl_setup_node_tests(void)
+{
+	test_sysctl_calc_match_int_ok();
 	test_data.bitmap_0001 = kzalloc(SYSCTL_TEST_BITMAP_SIZE/8, GFP_KERNEL);
 	if (!test_data.bitmap_0001)
 		return -ENOMEM;
@@ -162,8 +166,18 @@ static int __init test_sysctl_init(void)
 		kfree(test_data.bitmap_0001);
 		return -ENOMEM;
 	}
+
 	return 0;
 }
+
+static int __init test_sysctl_init(void)
+{
+	int err;
+
+	err = test_sysctl_setup_node_tests();
+
+	return err;
+}
 module_init(test_sysctl_init);
 
 static void __exit test_sysctl_exit(void)
-- 
2.30.2

[PATCH v2 4/8] test_sysctl: Add an unregister sysctl test

[Joel Granados]

Add a test that checks that the unregistered directory is removed from
/proc/sys/debug

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 lib/test_sysctl.c                        | 30 ++++++++++++++++++++++++
 tools/testing/selftests/sysctl/sysctl.sh | 16 +++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/lib/test_sysctl.c b/lib/test_sysctl.c
index 0cf7c547d61a..555244687443 100644
--- a/lib/test_sysctl.c
+++ b/lib/test_sysctl.c
@@ -170,12 +170,42 @@ static int test_sysctl_setup_node_tests(void)
 	return 0;
 }
 
+/* Used to test that unregister actually removes the directory */
+static struct ctl_table test_table_unregister[] = {
+	{
+		.procname	= "unregister_error",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+	},
+	{}
+};
+
+static int test_sysctl_run_unregister_nested(void)
+{
+	struct ctl_table_header *unregister;
+
+	unregister = register_sysctl("debug/test_sysctl/unregister_error",
+				   test_table_unregister);
+	if (!unregister)
+		return -ENOMEM;
+
+	unregister_sysctl_table(unregister);
+	return 0;
+}
+
 static int __init test_sysctl_init(void)
 {
 	int err;
 
 	err = test_sysctl_setup_node_tests();
+	if (err)
+		goto out;
 
+	err = test_sysctl_run_unregister_nested();
+
+out:
 	return err;
 }
 module_init(test_sysctl_init);
diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index cb8f83dfe16b..a6d79d7a36e4 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -31,6 +31,7 @@ ALL_TESTS="$ALL_TESTS 0005:3:1:int_0003"
 ALL_TESTS="$ALL_TESTS 0006:50:1:bitmap_0001"
 ALL_TESTS="$ALL_TESTS 0007:1:1:boot_int"
 ALL_TESTS="$ALL_TESTS 0008:1:1:match_int"
+ALL_TESTS="$ALL_TESTS 0009:1:1:unregister_error"
 
 function allow_user_defaults()
 {
@@ -797,6 +798,20 @@ sysctl_test_0008()
 	return 0
 }
 
+sysctl_test_0009()
+{
+	TARGET="${SYSCTL}/$(get_test_target 0009)"
+	echo -n "Testing if $TARGET unregistered correctly ..."
+	if [ -d $TARGET ]; then
+		echo "TEST FAILED"
+		rc=1
+		test_rc
+	fi
+
+	echo "ok"
+	return 0
+}
+
 list_tests()
 {
 	echo "Test ID list:"
@@ -813,6 +828,7 @@ list_tests()
 	echo "0006 x $(get_test_count 0006) - tests proc_do_large_bitmap()"
 	echo "0007 x $(get_test_count 0007) - tests setting sysctl from kernel boot param"
 	echo "0008 x $(get_test_count 0008) - tests sysctl macro values match"
+	echo "0009 x $(get_test_count 0009) - tests sysct unregister"
 }
 
 usage()
-- 
2.30.2

[PATCH v2 5/8] test_sysctl: Add an option to prevent test skip

[Joel Granados]

Tests were being skipped because the target was not present. Add a flag
that controls whether to skip a test based on the presence of the target.
Actually skip tests in the test_case function with a "return" instead of
a "continue".

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 tools/testing/selftests/sysctl/sysctl.sh | 66 ++++++++++++++++--------
 1 file changed, 44 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index a6d79d7a36e4..9c0e9711138b 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -14,24 +14,26 @@ TEST_FILE=$(mktemp)
 
 # This represents
 #
-# TEST_ID:TEST_COUNT:ENABLED:TARGET
+# TEST_ID:TEST_COUNT:ENABLED:TARGET:SKIP_NO_TARGET
 #
 # TEST_ID: is the test id number
 # TEST_COUNT: number of times we should run the test
 # ENABLED: 1 if enabled, 0 otherwise
 # TARGET: test target file required on the test_sysctl module
+# SKIP_NO_TARGET: 1 skip if TARGET not there
+#                 0 run eventhough TARGET not there
 #
 # Once these are enabled please leave them as-is. Write your own test,
 # we have tons of space.
-ALL_TESTS="0001:1:1:int_0001"
-ALL_TESTS="$ALL_TESTS 0002:1:1:string_0001"
-ALL_TESTS="$ALL_TESTS 0003:1:1:int_0002"
-ALL_TESTS="$ALL_TESTS 0004:1:1:uint_0001"
-ALL_TESTS="$ALL_TESTS 0005:3:1:int_0003"
-ALL_TESTS="$ALL_TESTS 0006:50:1:bitmap_0001"
-ALL_TESTS="$ALL_TESTS 0007:1:1:boot_int"
-ALL_TESTS="$ALL_TESTS 0008:1:1:match_int"
-ALL_TESTS="$ALL_TESTS 0009:1:1:unregister_error"
+ALL_TESTS="0001:1:1:int_0001:1"
+ALL_TESTS="$ALL_TESTS 0002:1:1:string_0001:1"
+ALL_TESTS="$ALL_TESTS 0003:1:1:int_0002:1"
+ALL_TESTS="$ALL_TESTS 0004:1:1:uint_0001:1"
+ALL_TESTS="$ALL_TESTS 0005:3:1:int_0003:1"
+ALL_TESTS="$ALL_TESTS 0006:50:1:bitmap_0001:1"
+ALL_TESTS="$ALL_TESTS 0007:1:1:boot_int:1"
+ALL_TESTS="$ALL_TESTS 0008:1:1:match_int:1"
+ALL_TESTS="$ALL_TESTS 0009:1:1:unregister_error:0"
 
 function allow_user_defaults()
 {
@@ -614,7 +616,6 @@ target_exists()
 	TEST_ID="$2"
 
 	if [ ! -f ${TARGET} ] ; then
-		echo "Target for test $TEST_ID: $TARGET not exist, skipping test ..."
 		return 0
 	fi
 	return 1
@@ -902,16 +903,36 @@ function get_test_target()
 	echo ${TEST_DATA} | awk -F":" '{print $4}'
 }
 
+function get_test_skip_no_target()
+{
+	test_num $1
+	awk_field=$(remove_leading_zeros $1)
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$awk_field'}')
+	echo ${TEST_DATA} | awk -F":" '{print $5}'
+}
+
+function skip_test()
+{
+	TEST_ID=$1
+	TEST_TARGET=$2
+	if target_exists $TEST_TARGET $TEST_ID; then
+		TEST_SKIP=$(get_test_skip_no_target $TEST_ID)
+		if [[ $TEST_SKIP -eq "1" ]]; then
+			echo "Target for test $TEST_ID: $TEST_TARGET not exist, skipping test ..."
+			return 0
+		fi
+	fi
+	return 1
+}
+
 function run_all_tests()
 {
 	for i in $ALL_TESTS ; do
-		TEST_ID=${i%:*:*:*}
+		TEST_ID=${i%:*:*:*:*}
 		ENABLED=$(get_test_enabled $TEST_ID)
 		TEST_COUNT=$(get_test_count $TEST_ID)
 		TEST_TARGET=$(get_test_target $TEST_ID)
-		if target_exists $TEST_TARGET $TEST_ID; then
-			continue
-		fi
+
 		if [[ $ENABLED -eq "1" ]]; then
 			test_case $TEST_ID $TEST_COUNT $TEST_TARGET
 		fi
@@ -946,18 +967,19 @@ function watch_case()
 
 function test_case()
 {
+	TEST_ID=$1
 	NUM_TESTS=$2
+	TARGET=$3
 
-	i=0
-
-	if target_exists $3 $1; then
-		continue
+	if skip_test $TEST_ID $TARGET; then
+		return
 	fi
 
+	i=0
 	while [ $i -lt $NUM_TESTS ]; do
-		test_num $1
-		watch_log $i ${TEST_NAME}_test_$1 noclear
-		RUN_TEST=${TEST_NAME}_test_$1
+		test_num $TEST_ID
+		watch_log $i ${TEST_NAME}_test_${TEST_ID} noclear
+		RUN_TEST=${TEST_NAME}_test_${TEST_ID}
 		$RUN_TEST
 		let i=$i+1
 	done
-- 
2.30.2

[PATCH v2 6/8] test_sysclt: Test for registering a mount point

[Joel Granados]

Test that target gets created by register_sysctl_mount_point and that no
additional target can be created "on top" of a permanently empty sysctl
table.

Create a mount point target (mnt) in the sysctl test driver; try to
create another on top of that (mnt_error). Output an error if
"mnt_error" is present when we run the sysctl selftests.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 lib/test_sysctl.c                        | 45 ++++++++++++++++++++----
 tools/testing/selftests/sysctl/sysctl.sh | 16 +++++++++
 2 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/lib/test_sysctl.c b/lib/test_sysctl.c
index 555244687443..8036aa91a1cb 100644
--- a/lib/test_sysctl.c
+++ b/lib/test_sysctl.c
@@ -30,6 +30,13 @@ static int i_zero;
 static int i_one_hundred = 100;
 static int match_int_ok = 1;
 
+
+static struct {
+	struct ctl_table_header *test_h_setup_node;
+	struct ctl_table_header *test_h_mnt;
+	struct ctl_table_header *test_h_mnterror;
+} sysctl_test_headers;
+
 struct test_sysctl_data {
 	int int_0001;
 	int int_0002;
@@ -153,16 +160,14 @@ static void test_sysctl_calc_match_int_ok(void)
 			match_int_ok = 0;
 }
 
-static struct ctl_table_header *test_sysctl_header;
-
 static int test_sysctl_setup_node_tests(void)
 {
 	test_sysctl_calc_match_int_ok();
 	test_data.bitmap_0001 = kzalloc(SYSCTL_TEST_BITMAP_SIZE/8, GFP_KERNEL);
 	if (!test_data.bitmap_0001)
 		return -ENOMEM;
-	test_sysctl_header = register_sysctl("debug/test_sysctl", test_table);
-	if (!test_sysctl_header) {
+	sysctl_test_headers.test_h_setup_node = register_sysctl("debug/test_sysctl", test_table);
+	if (!sysctl_test_headers.test_h_setup_node) {
 		kfree(test_data.bitmap_0001);
 		return -ENOMEM;
 	}
@@ -195,6 +200,26 @@ static int test_sysctl_run_unregister_nested(void)
 	return 0;
 }
 
+static int test_sysctl_run_register_mount_point(void)
+{
+	sysctl_test_headers.test_h_mnt
+		= register_sysctl_mount_point("debug/test_sysctl/mnt");
+	if (!sysctl_test_headers.test_h_mnt)
+		return -ENOMEM;
+
+	sysctl_test_headers.test_h_mnterror
+		= register_sysctl("debug/test_sysctl/mnt/mnt_error",
+				  test_table_unregister);
+	/*
+	 * Don't check the result.:
+	 * If it fails (expected behavior), return 0.
+	 * If successful (missbehavior of register mount point), we want to see
+	 * mnt_error when we run the sysctl test script
+	 */
+
+	return 0;
+}
+
 static int __init test_sysctl_init(void)
 {
 	int err;
@@ -204,6 +229,10 @@ static int __init test_sysctl_init(void)
 		goto out;
 
 	err = test_sysctl_run_unregister_nested();
+	if (err)
+		goto out;
+
+	err = test_sysctl_run_register_mount_point();
 
 out:
 	return err;
@@ -213,8 +242,12 @@ module_init(test_sysctl_init);
 static void __exit test_sysctl_exit(void)
 {
 	kfree(test_data.bitmap_0001);
-	if (test_sysctl_header)
-		unregister_sysctl_table(test_sysctl_header);
+	if (sysctl_test_headers.test_h_setup_node)
+		unregister_sysctl_table(sysctl_test_headers.test_h_setup_node);
+	if (sysctl_test_headers.test_h_mnt)
+		unregister_sysctl_table(sysctl_test_headers.test_h_mnt);
+	if (sysctl_test_headers.test_h_mnterror)
+		unregister_sysctl_table(sysctl_test_headers.test_h_mnterror);
 }
 
 module_exit(test_sysctl_exit);
diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index 9c0e9711138b..444b2befda82 100755
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -34,6 +34,7 @@ ALL_TESTS="$ALL_TESTS 0006:50:1:bitmap_0001:1"
 ALL_TESTS="$ALL_TESTS 0007:1:1:boot_int:1"
 ALL_TESTS="$ALL_TESTS 0008:1:1:match_int:1"
 ALL_TESTS="$ALL_TESTS 0009:1:1:unregister_error:0"
+ALL_TESTS="$ALL_TESTS 0010:1:1:mnt/mnt_error:0"
 
 function allow_user_defaults()
 {
@@ -813,6 +814,20 @@ sysctl_test_0009()
 	return 0
 }
 
+sysctl_test_0010()
+{
+	TARGET="${SYSCTL}/$(get_test_target 0010)"
+	echo -n "Testing that $TARGET was not created  ..."
+	if [ -d $TARGET ]; then
+		echo "TEST FAILED"
+		rc=1
+		test_rc
+	fi
+
+	echo "ok"
+	return 0
+}
+
 list_tests()
 {
 	echo "Test ID list:"
@@ -830,6 +845,7 @@ list_tests()
 	echo "0007 x $(get_test_count 0007) - tests setting sysctl from kernel boot param"
 	echo "0008 x $(get_test_count 0008) - tests sysctl macro values match"
 	echo "0009 x $(get_test_count 0009) - tests sysct unregister"
+	echo "0010 x $(get_test_count 0010) - tests sysct mount point"
 }
 
 usage()
-- 
2.30.2

[PATCH v2 7/8] sysctl: Remove debugging dump_stack

[Joel Granados]

Remove unneeded dump_stack in __register_sysctl_table

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 fs/proc/proc_sysctl.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 8873812d22f3..07804097f997 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1406,7 +1406,6 @@ struct ctl_table_header *__register_sysctl_table(
 	spin_unlock(&sysctl_lock);
 fail:
 	kfree(header);
-	dump_stack();
 	return NULL;
 }
 
-- 
2.30.2

[PATCH v2 8/8] sysctl: replace child with an enumeration

[Joel Granados]

This is part of the effort to remove the empty element at the end of
ctl_table structs. "child" was a deprecated elem in this struct and was
being used to differentiate between two types of ctl_tables: "normal"
and "permanently emtpy".

What changed?:
* Replace "child" with an enumeration that will have two values: the
  default (0) and the permanently empty (1). The latter is left at zero
  so when struct ctl_table is created with kzalloc or in a local
  context, it will have the zero value by default. We document the
  new enum with kdoc.
* Remove the "empty child" check from sysctl_check_table
* Remove count_subheaders function as there is no longer a need to
  calculate how many headers there are for every child
* Remove the recursive call to unregister_sysctl_table as there is no
  need to traverse down the child tree any longer
* Add a new SYSCTL_PERM_EMPTY_DIR binary flag
* Remove the last remanence of child from partport/procfs.c

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 drivers/parport/procfs.c |  1 -
 fs/proc/proc_sysctl.c    | 81 +++++++++-------------------------------
 include/linux/sysctl.h   | 14 ++++++-
 3 files changed, 30 insertions(+), 66 deletions(-)

diff --git a/drivers/parport/procfs.c b/drivers/parport/procfs.c
index 0f2d2e1ee28e..4e5b972c3e26 100644
--- a/drivers/parport/procfs.c
+++ b/drivers/parport/procfs.c
@@ -387,7 +387,6 @@ parport_device_sysctl_template = {
 			.data		= NULL,
 			.maxlen		= 0,
 			.mode		= 0555,
-			.child		= NULL
 		},
 		{}
 	}
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 07804097f997..c4ea804d862b 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -29,9 +29,8 @@ static const struct file_operations proc_sys_dir_file_operations;
 static const struct inode_operations proc_sys_dir_operations;
 
 /* Support for permanently empty directories */
-
 struct ctl_table sysctl_mount_point[] = {
-	{ }
+	{.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY }
 };
 
 /**
@@ -48,21 +47,14 @@ struct ctl_table_header *register_sysctl_mount_point(const char *path)
 }
 EXPORT_SYMBOL(register_sysctl_mount_point);
 
-static bool is_empty_dir(struct ctl_table_header *head)
-{
-	return head->ctl_table[0].child == sysctl_mount_point;
-}
-
-static void set_empty_dir(struct ctl_dir *dir)
-{
-	dir->header.ctl_table[0].child = sysctl_mount_point;
-}
-
-static void clear_empty_dir(struct ctl_dir *dir)
-
-{
-	dir->header.ctl_table[0].child = NULL;
-}
+#define sysctl_is_perm_empty_ctl_table(tptr)		\
+	(tptr[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
+#define sysctl_is_perm_empty_ctl_header(hptr)		\
+	(sysctl_is_perm_empty_ctl_table(hptr->ctl_table))
+#define sysctl_set_perm_empty_ctl_header(hptr)		\
+	(hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
+#define sysctl_clear_perm_empty_ctl_header(hptr)	\
+	(hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT)
 
 void proc_sys_poll_notify(struct ctl_table_poll *poll)
 {
@@ -230,20 +222,22 @@ static void erase_header(struct ctl_table_header *head)
 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
 {
 	struct ctl_table *entry;
+	struct ctl_table_header *dir_h = &dir->header;
 	int err;
 
+
 	/* Is this a permanently empty directory? */
-	if (is_empty_dir(&dir->header))
+	if (sysctl_is_perm_empty_ctl_header(dir_h))
 		return -EROFS;
 
 	/* Am I creating a permanently empty directory? */
-	if (header->ctl_table == sysctl_mount_point) {
+	if (sysctl_is_perm_empty_ctl_table(header->ctl_table)) {
 		if (!RB_EMPTY_ROOT(&dir->root))
 			return -EINVAL;
-		set_empty_dir(dir);
+		sysctl_set_perm_empty_ctl_header(dir_h);
 	}
 
-	dir->header.nreg++;
+	dir_h->nreg++;
 	header->parent = dir;
 	err = insert_links(header);
 	if (err)
@@ -259,9 +253,9 @@ static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
 	put_links(header);
 fail_links:
 	if (header->ctl_table == sysctl_mount_point)
-		clear_empty_dir(dir);
+		sysctl_clear_perm_empty_ctl_header(dir_h);
 	header->parent = NULL;
-	drop_sysctl_table(&dir->header);
+	drop_sysctl_table(dir_h);
 	return err;
 }
 
@@ -479,7 +473,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
 		inode->i_mode |= S_IFDIR;
 		inode->i_op = &proc_sys_dir_operations;
 		inode->i_fop = &proc_sys_dir_file_operations;
-		if (is_empty_dir(head))
+		if (sysctl_is_perm_empty_ctl_header(head))
 			make_empty_dir_inode(inode);
 	}
 
@@ -1136,9 +1130,6 @@ static int sysctl_check_table(const char *path, struct ctl_table *table)
 	struct ctl_table *entry;
 	int err = 0;
 	list_for_each_table_entry(entry, table) {
-		if (entry->child)
-			err |= sysctl_err(path, entry, "Not a file");
-
 		if ((entry->proc_handler == proc_dostring) ||
 		    (entry->proc_handler == proc_dobool) ||
 		    (entry->proc_handler == proc_dointvec) ||
@@ -1465,25 +1456,6 @@ void __init __register_sysctl_init(const char *path, struct ctl_table *table,
 	kmemleak_not_leak(hdr);
 }
 
-static int count_subheaders(struct ctl_table *table)
-{
-	int has_files = 0;
-	int nr_subheaders = 0;
-	struct ctl_table *entry;
-
-	/* special case: no directory and empty directory */
-	if (!table || !table->procname)
-		return 1;
-
-	list_for_each_table_entry(entry, table) {
-		if (entry->child)
-			nr_subheaders += count_subheaders(entry->child);
-		else
-			has_files = 1;
-	}
-	return nr_subheaders + has_files;
-}
-
 static void put_links(struct ctl_table_header *header)
 {
 	struct ctl_table_set *root_set = &sysctl_table_root.default_set;
@@ -1546,28 +1518,11 @@ static void drop_sysctl_table(struct ctl_table_header *header)
  */
 void unregister_sysctl_table(struct ctl_table_header * header)
 {
-	int nr_subheaders;
 	might_sleep();
 
 	if (header == NULL)
 		return;
 
-	nr_subheaders = count_subheaders(header->ctl_table_arg);
-	if (unlikely(nr_subheaders > 1)) {
-		struct ctl_table_header **subheaders;
-		int i;
-
-		subheaders = (struct ctl_table_header **)(header + 1);
-		for (i = nr_subheaders -1; i >= 0; i--) {
-			struct ctl_table_header *subh = subheaders[i];
-			struct ctl_table *table = subh->ctl_table_arg;
-			unregister_sysctl_table(subh);
-			kfree(table);
-		}
-		kfree(header);
-		return;
-	}
-
 	spin_lock(&sysctl_lock);
 	drop_sysctl_table(header);
 	spin_unlock(&sysctl_lock);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 653b66c762b1..59d451f455bf 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -137,7 +137,17 @@ struct ctl_table {
 	void *data;
 	int maxlen;
 	umode_t mode;
-	struct ctl_table *child;	/* Deprecated */
+	/**
+	 * enum type - Enumeration to differentiate between ctl target types
+	 * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations
+	 * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently
+	 *                                       empty directory target to serve
+	 *                                       as mount point.
+	 */
+	enum {
+		SYSCTL_TABLE_TYPE_DEFAULT,
+		SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY
+	} type;
 	proc_handler *proc_handler;	/* Callback for text formatting */
 	struct ctl_table_poll *poll;
 	void *extra1;
@@ -229,7 +239,7 @@ extern int unaligned_enabled;
 extern int unaligned_dump_stack;
 extern int no_unaligned_warning;
 
-extern struct ctl_table sysctl_mount_point[];
+#define SYSCTL_PERM_EMPTY_DIR	(1 << 0)
 
 #else /* CONFIG_SYSCTL */
 
-- 
2.30.2

Re: [PATCH v2 0/8] Remove child from struct ctl_table

[Luis Chamberlain]

On Fri, Jun 16, 2023 at 10:59:14AM +0200, Joel Granados wrote:
> This is part of the effort to remove the empty element of the ctl_table
> structures (used to calculate size) and replace it with an ARRAY_SIZE call. By
> replacing the child element in struct ctl_table with a flags element we make
> sure that there are no forward recursions on child nodes and therefore set
> ourselves up for just using an ARRAY_SIZE. We also added some self tests to
> make sure that we do not break anything.
> 
> Patchset is separated in 4: parport fixes, selftests fixes, selftests additions and
> replacement of child element. Tested everything with sysctl self tests and everything
> seems "ok".
> 
> 1. parport fixes: This is related to my previous series and it plugs a sysct
>    table leak in the parport driver. @mcgrof: I'm just leaving this here so we
>    don't have to retest the parport stuff
> 
> 2. Selftests fixes: Remove the prefixed zeros when passing a awk field to the
>    awk print command because it was causing $0009 to be interpreted as $0.
>    Replaced continue with return in sysctl.sh(test_case) so the test actually
>    gets skipped. The skip decision is now in sysctl.sh(skip_test).
> 
> 3. Selftest additions: New test to confirm that unregister actually removes
>    targets. New test to confirm that permanently empty targets are indeed
>    created and that no other targets can be created "on top".
> 
> 4. Replaced the child pointer in struct ctl_table with an enum which is used to
>    differentiate between permanently empty targets and non-empty ones.
> 
> V2: Replaced the u8 flag with an enumeration.

Thanks, I dropped the old patches and applied this new set. Pushed out
to sysctl-next.

  Luis

Re: [PATCH v2 0/8] Remove child from struct ctl_table

[Joel Granados]

[-- Attachment #1: Type: text/plain, Size: 1936 bytes --]

On Sun, Jun 18, 2023 at 02:33:35AM -0700, Luis Chamberlain wrote:
> On Fri, Jun 16, 2023 at 10:59:14AM +0200, Joel Granados wrote:
> > This is part of the effort to remove the empty element of the ctl_table
> > structures (used to calculate size) and replace it with an ARRAY_SIZE call. By
> > replacing the child element in struct ctl_table with a flags element we make
> > sure that there are no forward recursions on child nodes and therefore set
> > ourselves up for just using an ARRAY_SIZE. We also added some self tests to
> > make sure that we do not break anything.
> > 
> > Patchset is separated in 4: parport fixes, selftests fixes, selftests additions and
> > replacement of child element. Tested everything with sysctl self tests and everything
> > seems "ok".
> > 
> > 1. parport fixes: This is related to my previous series and it plugs a sysct
> >    table leak in the parport driver. @mcgrof: I'm just leaving this here so we
> >    don't have to retest the parport stuff
> > 
> > 2. Selftests fixes: Remove the prefixed zeros when passing a awk field to the
> >    awk print command because it was causing $0009 to be interpreted as $0.
> >    Replaced continue with return in sysctl.sh(test_case) so the test actually
> >    gets skipped. The skip decision is now in sysctl.sh(skip_test).
> > 
> > 3. Selftest additions: New test to confirm that unregister actually removes
> >    targets. New test to confirm that permanently empty targets are indeed
> >    created and that no other targets can be created "on top".
> > 
> > 4. Replaced the child pointer in struct ctl_table with an enum which is used to
> >    differentiate between permanently empty targets and non-empty ones.
> > 
> > V2: Replaced the u8 flag with an enumeration.
> 
> Thanks, I dropped the old patches and applied this new set. Pushed out
> to sysctl-next.
Awesome! thx.
> 
>   Luis

-- 

Joel Granados

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