From a78341bcd85d5d73a299843d28a6b47e747659cd Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Date: Sat, 16 Jan 2021 03:39:35 +0100
Subject: [PATCH] net: dsa: mv88e6xxx: also read STU state in
 mv88e6250_g1_vtu_getnext
Git-commit: 87fe04367d842c4d97a77303242d4dd4ac351e46
References: git-fixes
Patch-mainline: v5.11-rc5

mv88e6xxx_port_vlan_join checks whether the VTU already contains an
entry for the given vid (via mv88e6xxx_vtu_getnext), and if so, merely
changes the relevant .member[] element and loads the updated entry
into the VTU.

However, at least for the mv88e6250, the on-stack struct
mv88e6xxx_vtu_entry vlan never has its .state[] array explicitly
initialized, neither in mv88e6xxx_port_vlan_join() nor inside the
getnext implementation. So the new entry has random garbage for the
STU bits, breaking VLAN filtering.

When the VTU entry is initially created, those bits are all zero, and
we should make sure to keep them that way when the entry is updated.

Fixes: 92307069a96c (net: dsa: mv88e6xxx: Avoid VTU corruption on 6097)
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Tobias Waldekranz <tobias@waldekranz.com>
Tested-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/dsa/mv88e6xxx/global1_vtu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/dsa/mv88e6xxx/global1_vtu.c b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
index 2d45a8acdc74..667006bd01d5 100644
--- a/drivers/net/dsa/mv88e6xxx/global1_vtu.c
+++ b/drivers/net/dsa/mv88e6xxx/global1_vtu.c
@@ -349,6 +349,10 @@ int mv88e6250_g1_vtu_getnext(struct mv88e6xxx_chip *chip,
 		if (err)
 			return err;
 
+		err = mv88e6185_g1_stu_data_read(chip, entry);
+		if (err)
+			return err;
+
 		/* VTU DBNum[3:0] are located in VTU Operation 3:0
 		 * VTU DBNum[5:4] are located in VTU Operation 9:8
 		 */
-- 
2.16.4