linux_dsm_epyc7002/net
Vladimir Oltean 4ba0ebbc6c net: dsa: Fix off-by-one number of calls to devlink_port_unregister
When a function such as dsa_slave_create fails, currently the following
stack trace can be seen:

[    2.038342] sja1105 spi0.1: Probed switch chip: SJA1105T
[    2.054556] sja1105 spi0.1: Reset switch and programmed static config
[    2.063837] sja1105 spi0.1: Enabled switch tagging
[    2.068706] fsl-gianfar soc:ethernet@2d90000 eth2: error -19 setting up slave phy
[    2.076371] ------------[ cut here ]------------
[    2.080973] WARNING: CPU: 1 PID: 21 at net/core/devlink.c:6184 devlink_free+0x1b4/0x1c0
[    2.088954] Modules linked in:
[    2.092005] CPU: 1 PID: 21 Comm: kworker/1:1 Not tainted 5.3.0-rc6-01360-g41b52e38d2b6-dirty #1746
[    2.100912] Hardware name: Freescale LS1021A
[    2.105162] Workqueue: events deferred_probe_work_func
[    2.110287] [<c03133a4>] (unwind_backtrace) from [<c030d8cc>] (show_stack+0x10/0x14)
[    2.117992] [<c030d8cc>] (show_stack) from [<c10b08d8>] (dump_stack+0xb4/0xc8)
[    2.125180] [<c10b08d8>] (dump_stack) from [<c0349d04>] (__warn+0xe0/0xf8)
[    2.132018] [<c0349d04>] (__warn) from [<c0349e34>] (warn_slowpath_null+0x40/0x48)
[    2.139549] [<c0349e34>] (warn_slowpath_null) from [<c0f19d74>] (devlink_free+0x1b4/0x1c0)
[    2.147772] [<c0f19d74>] (devlink_free) from [<c1064fc0>] (dsa_switch_teardown+0x60/0x6c)
[    2.155907] [<c1064fc0>] (dsa_switch_teardown) from [<c1065950>] (dsa_register_switch+0x8e4/0xaa8)
[    2.164821] [<c1065950>] (dsa_register_switch) from [<c0ba7fe4>] (sja1105_probe+0x21c/0x2ec)
[    2.173216] [<c0ba7fe4>] (sja1105_probe) from [<c0b35948>] (spi_drv_probe+0x80/0xa4)
[    2.180920] [<c0b35948>] (spi_drv_probe) from [<c0a4c1cc>] (really_probe+0x108/0x400)
[    2.188711] [<c0a4c1cc>] (really_probe) from [<c0a4c694>] (driver_probe_device+0x78/0x1bc)
[    2.196933] [<c0a4c694>] (driver_probe_device) from [<c0a4a3dc>] (bus_for_each_drv+0x58/0xb8)
[    2.205414] [<c0a4a3dc>] (bus_for_each_drv) from [<c0a4c024>] (__device_attach+0xd0/0x168)
[    2.213637] [<c0a4c024>] (__device_attach) from [<c0a4b1d0>] (bus_probe_device+0x84/0x8c)
[    2.221772] [<c0a4b1d0>] (bus_probe_device) from [<c0a4b72c>] (deferred_probe_work_func+0x84/0xc4)
[    2.230686] [<c0a4b72c>] (deferred_probe_work_func) from [<c03650a4>] (process_one_work+0x218/0x510)
[    2.239772] [<c03650a4>] (process_one_work) from [<c03660d8>] (worker_thread+0x2a8/0x5c0)
[    2.247908] [<c03660d8>] (worker_thread) from [<c036b348>] (kthread+0x148/0x150)
[    2.255265] [<c036b348>] (kthread) from [<c03010e8>] (ret_from_fork+0x14/0x2c)
[    2.262444] Exception stack(0xea965fb0 to 0xea965ff8)
[    2.267466] 5fa0:                                     00000000 00000000 00000000 00000000
[    2.275598] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.283729] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    2.290333] ---[ end trace ca5d506728a0581a ]---

devlink_free is complaining right here:

	WARN_ON(!list_empty(&devlink->port_list));

This happens because devlink_port_unregister is no longer done right
away in dsa_port_setup when a DSA_PORT_TYPE_USER has failed.
Vivien said about this change that:

    Also no need to call devlink_port_unregister from within dsa_port_setup
    as this step is inconditionally handled by dsa_port_teardown on error.

which is not really true. The devlink_port_unregister function _is_
being called unconditionally from within dsa_port_setup, but not for
this port that just failed, just for the previous ones which were set
up.

ports_teardown:
	for (i = 0; i < port; i++)
		dsa_port_teardown(&ds->ports[i]);

Initially I was tempted to fix this by extending the "for" loop to also
cover the port that failed during setup. But this could have potentially
unforeseen consequences unrelated to devlink_port or even other types of
ports than user ports, which I can't really test for. For example, if
for some reason devlink_port_register itself would fail, then
unconditionally unregistering it in dsa_port_teardown would not be a
smart idea. The list might go on.

So just make dsa_port_setup undo the setup it had done upon failure, and
let the for loop undo the work of setting up the previous ports, which
are guaranteed to be brought up to a consistent state.

Fixes: 955222ca52 ("net: dsa: use a single switch statement for port setup")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-09-02 11:59:29 -07:00
..
6lowpan
9p
802
8021q
appletalk
atm
ax25
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
bluetooth
bpf
bpfilter
bridge Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
caif
can
ceph libceph: don't call crypto_free_sync_skcipher() on a NULL tfm 2019-08-28 12:33:46 +02:00
core Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
dcb
dccp
decnet
dns_resolver
dsa net: dsa: Fix off-by-one number of calls to devlink_port_unregister 2019-09-02 11:59:29 -07:00
ethernet
hsr
ieee802154
ife
ipv4 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
ipv6 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
iucv
kcm
key
l2tp
l3mdev
lapb
llc
mac80211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
mac802154
mpls
ncsi net/ncsi: add response handlers for PLDM over NC-SI 2019-08-31 23:54:03 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
netlabel netlabel: remove redundant assignment to pointer iter 2019-09-01 11:45:02 -07:00
netlink
netrom
nfc
nsh
openvswitch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
packet
phonet
psample net: sched: act_sample: fix psample group handling on overwrite 2019-08-28 15:53:51 -07:00
qrtr
rds Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
rfkill
rose
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-02 11:20:17 -07:00
sctp sctp: allow users to set ep ecn flag by sockopt 2019-08-27 20:54:14 -07:00
smc
strparser
sunrpc
switchdev
tipc
tls net: tls: export protocol version, cipher, tx_conf/rx_conf to socket diag 2019-08-31 23:44:28 -07:00
unix
vmw_vsock
wimax
wireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-27 14:23:31 -07:00
x25
xdp Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-27 14:23:31 -07:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-27 14:23:31 -07:00
compat.c
Kconfig
Makefile
socket.c
sysctl_net.c