[LTP] [PATCH v4 22/31] testcases: sysfs: Add sys_net03

[Cyril Hrubis]

A test for /sys/class/net/*/* files.

Similar to sys_net02 but checks bridge related files after briding a
virtual ethernet interface.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 runtest/sysfs                                |   1 +
 testcases/kernel/sysfs/class/net/.gitignore  |   1 +
 testcases/kernel/sysfs/class/net/sys_net03.c | 145 +++++++++++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 testcases/kernel/sysfs/class/net/sys_net03.c

diff --git a/runtest/sysfs b/runtest/sysfs
index fee8a0b2b..b2cc0005c 100644
--- a/runtest/sysfs
+++ b/runtest/sysfs
@@ -17,3 +17,4 @@ sys_rtc01 sys_rtc01
 sys_thermal01 sys_thermal01
 sys_net01 sys_net01
 sys_net02 sys_net02
+sys_net03 sys_net03
diff --git a/testcases/kernel/sysfs/class/net/.gitignore b/testcases/kernel/sysfs/class/net/.gitignore
index b70d02158..8c3782a3b 100644
--- a/testcases/kernel/sysfs/class/net/.gitignore
+++ b/testcases/kernel/sysfs/class/net/.gitignore
@@ -1,2 +1,3 @@
 /sys_net01
 /sys_net02
+/sys_net03
diff --git a/testcases/kernel/sysfs/class/net/sys_net03.c b/testcases/kernel/sysfs/class/net/sys_net03.c
new file mode 100644
index 000000000..eb8c484f4
--- /dev/null
+++ b/testcases/kernel/sysfs/class/net/sys_net03.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+/*\
+ * Verifies that bridge port sysfs attributes correctly appear, hold sane
+ * values, and disappear again as a network device is enslaved to and
+ * released from a bridge.
+ *
+ * The test creates a bridge and a veth pair, then:
+ *
+ * - verifies /sys/class/net/<bridge>/brif/ is empty and
+ *   /sys/class/net/<port>/brport does not exist before enslaving
+ * - enslaves one end of the veth pair to the bridge
+ * - verifies /sys/class/net/<bridge>/brif/<port> appears and
+ *   /sys/class/net/<port>/brport/{state,priority,path_cost} hold sane values
+ * - verifies /sys/class/net/<bridge>/bridge/{stp_state,forward_delay} hold
+ *   sane values
+ * - releases the port from the bridge
+ * - verifies /sys/class/net/<bridge>/brif/ is empty and
+ *   /sys/class/net/<port>/brport does not exist again
+ *
+ * This needs root to create the bridge and veth devices.
+ */
+
+#include <limits.h>
+#include <string.h>
+#include <dirent.h>
+#include <unistd.h>
+
+#include "tst_test.h"
+#include "tst_netdevice.h"
+#include "tst_sysfs_assert.h"
+#include "tst_path_defs.h"
+
+#define BRNAME "ltp_br0"
+#define IFNAME1 "ltp_vethb1"
+#define IFNAME2 "ltp_vethb2"
+
+#define BR_PATH PATH_CLASS_NET "/" BRNAME
+#define PORT_PATH PATH_CLASS_NET "/" IFNAME1
+
+static int bridge_created;
+static int veth_created;
+
+static int count_dir_entries(const char *path)
+{
+	DIR *d;
+	struct dirent *ent;
+	int count = 0;
+
+	d = TST_SYSFS_TRY_OPENDIR(path);
+
+	while ((ent = SAFE_READDIR(d))) {
+		if (ent->d_name[0] == '.')
+			continue;
+
+		count++;
+	}
+
+	SAFE_CLOSEDIR(d);
+
+	return count;
+}
+
+static void setup(void)
+{
+	NETDEV_ADD_DEVICE(BRNAME, "bridge");
+	bridge_created = 1;
+
+	CREATE_VETH_PAIR(IFNAME1, IFNAME2);
+	veth_created = 1;
+
+	NETDEV_SET_STATE(BRNAME, 1);
+	NETDEV_SET_STATE(IFNAME1, 1);
+	NETDEV_SET_STATE(IFNAME2, 1);
+}
+
+static void check_not_enslaved(const char *desc)
+{
+	int nports = count_dir_entries(BR_PATH "/brif");
+
+	tst_res(TINFO, "%s", desc);
+
+	TST_EXP_EQ_LI(nports, 0);
+
+	if (access(PORT_PATH "/brport", F_OK))
+		tst_res(TPASS, PORT_PATH "/brport does not exist");
+	else
+		tst_res(TFAIL, PORT_PATH "/brport unexpectedly exists");
+}
+
+static void check_enslaved(void)
+{
+	int nports = count_dir_entries(BR_PATH "/brif");
+
+	tst_res(TINFO, "port enslaved to bridge");
+
+	TST_EXP_EQ_LI(nports, 1);
+
+	if (!access(BR_PATH "/brif/" IFNAME1, F_OK))
+		tst_res(TPASS, BR_PATH "/brif/" IFNAME1 " exists");
+	else
+		tst_res(TFAIL, BR_PATH "/brif/" IFNAME1 " does not exist");
+
+	TST_SYSFS_ASSERT_RANGELL(0, 4, PORT_PATH "/brport/state");
+	TST_SYSFS_ASSERT_RANGELL(0, 255, PORT_PATH "/brport/priority");
+	TST_SYSFS_ASSERT_RANGELL(1, LONG_MAX, PORT_PATH "/brport/path_cost");
+
+	TST_SYSFS_ASSERT_RANGELL(0, 2, BR_PATH "/bridge/stp_state");
+	TST_SYSFS_ASSERT_RANGELL(1, LONG_MAX, BR_PATH "/bridge/forward_delay");
+}
+
+static void run(void)
+{
+	check_not_enslaved("before enslaving");
+
+	NETDEV_SET_MASTER(IFNAME1, BRNAME);
+	check_enslaved();
+
+	NETDEV_SET_MASTER(IFNAME1, NULL);
+	check_not_enslaved("after releasing");
+}
+
+static void cleanup(void)
+{
+	if (veth_created)
+		NETDEV_REMOVE_DEVICE(IFNAME1);
+
+	if (bridge_created)
+		NETDEV_REMOVE_DEVICE(BRNAME);
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.cleanup = cleanup,
+	.needs_root = 1,
+	.needs_kconfigs = (const char *const[]){
+		"CONFIG_VETH",
+		"CONFIG_BRIDGE",
+		NULL
+	},
+};
-- 
2.54.0