net: dsa: mv88e6xxx: fix software VLAN deletion

The current bridge code calls switchdev_port_obj_del on a VLAN port even
if the corresponding switchdev_port_obj_add call returned -EOPNOTSUPP.

If the DSA driver doesn't return -EOPNOTSUPP for a software port VLAN in
its port_vlan_del function, the VLAN is not deleted. Unbridging the port
also generates a stack trace for the same reason.

This can be quickly tested on a VLAN filtering enabled system with:

    # brctl addbr br0
    # brctl addif br0 lan0
    # brctl addbr br1
    # brctl addif br1 lan1
    # brctl delif br1 lan1

Both bridges have a default default_pvid set to 1. lan0 uses the
hardware VLAN 1 while lan1 falls back to the software VLAN 1.

Unbridging lan1 does not delete its software VLAN, and thus generates
the following stack trace:

    [ 2991.681705] device lan1 left promiscuous mode
    [ 2991.686237] br1: port 1(lan1) entered disabled state
    [ 2991.725094] ------------[ cut here ]------------
    [ 2991.729761] WARNING: CPU: 0 PID: 869 at net/bridge/br_vlan.c:314 __vlan_group_free+0x4c/0x50()
    [ 2991.738437] Modules linked in:
    [ 2991.741546] CPU: 0 PID: 869 Comm: ip Not tainted 4.4.0 #16
    [ 2991.747039] Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)
    [ 2991.753511] Backtrace:
    [ 2991.756008] [<80014450>] (dump_backtrace) from [<8001469c>] (show_stack+0x20/0x24)
    [ 2991.763604]  r6:80512644 r5:00000009 r4:00000000 r3:00000000
    [ 2991.769343] [<8001467c>] (show_stack) from [<80268e44>] (dump_stack+0x24/0x28)
    [ 2991.776618] [<80268e20>] (dump_stack) from [<80025568>] (warn_slowpath_common+0x98/0xc4)
    [ 2991.784750] [<800254d0>] (warn_slowpath_common) from [<80025650>] (warn_slowpath_null+0x2c/0x34)
    [ 2991.793557]  r8:00000000 r7:9f786a8c r6:9f76c440 r5:9f786a00 r4:9f68ac00
    [ 2991.800366] [<80025624>] (warn_slowpath_null) from [<80512644>] (__vlan_group_free+0x4c/0x50)
    [ 2991.808946] [<805125f8>] (__vlan_group_free) from [<80514488>] (nbp_vlan_flush+0x44/0x68)
    [ 2991.817147]  r4:9f68ac00 r3:9ec70000
    [ 2991.820772] [<80514444>] (nbp_vlan_flush) from [<80506f08>] (del_nbp+0xac/0x130)
    [ 2991.828201]  r5:9f56f800 r4:9f786a00
    [ 2991.831841] [<80506e5c>] (del_nbp) from [<8050774c>] (br_del_if+0x40/0xbc)
    [ 2991.838724]  r7:80590f68 r6:00000000 r5:9ec71c38 r4:9f76c440
    [ 2991.844475] [<8050770c>] (br_del_if) from [<80503dc0>] (br_del_slave+0x1c/0x20)
    [ 2991.851802]  r5:9ec71c38 r4:9f56f800
    [ 2991.855428] [<80503da4>] (br_del_slave) from [<80484a34>] (do_setlink+0x324/0x7b8)
    [ 2991.863043] [<80484710>] (do_setlink) from [<80485e90>] (rtnl_newlink+0x508/0x6f4)
    [ 2991.870616]  r10:00000000 r9:9ec71ba8 r8:00000000 r7:00000000 r6:9f6b0400 r5:9f56f800
    [ 2991.878548]  r4:8076278c
    [ 2991.881110] [<80485988>] (rtnl_newlink) from [<80484048>] (rtnetlink_rcv_msg+0x18c/0x22c)
    [ 2991.889315]  r10:9f7d4e40 r9:00000000 r8:00000000 r7:00000000 r6:9f7d4e40 r5:9f6b0400
    [ 2991.897250]  r4:00000000
    [ 2991.899814] [<80483ebc>] (rtnetlink_rcv_msg) from [<80497c74>] (netlink_rcv_skb+0xb0/0xcc)
    [ 2991.908104]  r8:00000000 r7:9f7d4e40 r6:9f7d4e40 r5:80483ebc r4:9f6b0400
    [ 2991.914928] [<80497bc4>] (netlink_rcv_skb) from [<80483eb4>] (rtnetlink_rcv+0x34/0x3c)
    [ 2991.922874]  r6:9f5ea000 r5:00000028 r4:9f7d4e40 r3:80483e80
    [ 2991.928622] [<80483e80>] (rtnetlink_rcv) from [<80497604>] (netlink_unicast+0x180/0x200)
    [ 2991.936742]  r4:9f4edc00 r3:80483e80
    [ 2991.940362] [<80497484>] (netlink_unicast) from [<80497a88>] (netlink_sendmsg+0x33c/0x350)
    [ 2991.948648]  r8:00000000 r7:00000028 r6:00000000 r5:9f5ea000 r4:9ec71f4c
    [ 2991.955481] [<8049774c>] (netlink_sendmsg) from [<80457ff0>] (sock_sendmsg+0x24/0x34)
    [ 2991.963342]  r10:00000000 r9:9ec71e28 r8:00000000 r7:9f1e2140 r6:00000000 r5:00000000
    [ 2991.971276]  r4:9ec71f4c
    [ 2991.973849] [<80457fcc>] (sock_sendmsg) from [<80458af0>] (___sys_sendmsg+0x1fc/0x204)
    [ 2991.981809] [<804588f4>] (___sys_sendmsg) from [<804598d0>] (__sys_sendmsg+0x4c/0x7c)
    [ 2991.989640]  r10:00000000 r9:9ec70000 r8:80010824 r7:00000128 r6:7ee946c4 r5:00000000
    [ 2991.997572]  r4:9f1e2140
    [ 2992.000128] [<80459884>] (__sys_sendmsg) from [<80459918>] (SyS_sendmsg+0x18/0x1c)
    [ 2992.007725]  r6:00000000 r5:7ee9c7b8 r4:7ee946e0
    [ 2992.012430] [<80459900>] (SyS_sendmsg) from [<80010660>] (ret_fast_syscall+0x0/0x3c)
    [ 2992.020182] ---[ end trace 5d4bc29f4da04280 ]---

To fix this, return -EOPNOTSUPP in _mv88e6xxx_port_vlan_del instead of
-ENOENT if the hardware VLAN doesn't exist or the port is not a member.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -1555,7 +1555,7 @@ static int _mv88e6xxx_port_vlan_del(struct dsa_switch *ds, int port, u16 vid)
 
 	if (vlan.vid != vid || !vlan.valid ||
 	    vlan.data[port] == GLOBAL_VTU_DATA_MEMBER_TAG_NON_MEMBER)
-		return -ENOENT;
+		return -EOPNOTSUPP;
 
 	vlan.data[port] = GLOBAL_VTU_DATA_MEMBER_TAG_NON_MEMBER;