linux/net/dsa
Vladimir Oltean 11fd667dac net: dsa: setup master before ports
It is said that as soon as a network interface is registered, all its
resources should have already been prepared, so that it is available for
sending and receiving traffic. One of the resources needed by a DSA
slave interface is the master.

dsa_tree_setup
-> dsa_tree_setup_ports
   -> dsa_port_setup
      -> dsa_slave_create
         -> register_netdevice
-> dsa_tree_setup_master
   -> dsa_master_setup
      -> sets up master->dsa_ptr, which enables reception

Therefore, there is a short period of time after register_netdevice()
during which the master isn't prepared to pass traffic to the DSA layer
(master->dsa_ptr is checked by eth_type_trans). Same thing during
unregistration, there is a time frame in which packets might be missed.

Note that this change opens us to another race: dsa_master_find_slave()
will get invoked potentially earlier than the slave creation, and later
than the slave deletion. Since dp->slave starts off as a NULL pointer,
the earlier calls aren't a problem, but the later calls are. To avoid
use-after-free, we should zeroize dp->slave before calling
dsa_slave_destroy().

In practice I cannot really test real life improvements brought by this
change, since in my systems, netdevice creation races with PHY autoneg
which takes a few seconds to complete, and that masks quite a few races.
Effects might be noticeable in a setup with fixed links all the way to
an external system.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-06 11:59:10 +00:00
..
dsa2.c net: dsa: setup master before ports 2022-01-06 11:59:10 +00:00
dsa_priv.h net: dsa: remove cross-chip support for HSR 2022-01-05 15:04:51 +00:00
dsa.c devlink: Simplify devlink resources unregister call 2021-11-30 12:23:32 +00:00
Kconfig net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag 2021-10-18 14:02:56 +01:00
Makefile net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag 2021-10-18 14:02:56 +01:00
master.c net: dsa: hold rtnl_mutex when calling dsa_master_{setup,teardown} 2022-01-06 11:59:10 +00:00
port.c net: dsa: remove cross-chip support for HSR 2022-01-05 15:04:51 +00:00
slave.c net: dsa: merge rtnl_lock sections in dsa_slave_create 2022-01-06 11:59:09 +00:00
switch.c net: dsa: remove cross-chip support for HSR 2022-01-05 15:04:51 +00:00
tag_8021q.c net: dsa: keep the bridge_dev and bridge_num as part of the same structure 2021-12-08 14:31:16 -08:00
tag_ar9331.c net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv() 2021-08-02 15:13:15 +01:00
tag_brcm.c net: dsa: create a helper for locating EtherType DSA headers on RX 2021-08-11 14:44:58 +01:00
tag_dsa.c net: dsa: hide dp->bridge_dev and dp->bridge_num in the core behind helpers 2021-12-08 14:31:15 -08:00
tag_gswip.c net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv() 2021-08-02 15:13:15 +01:00
tag_hellcreek.c net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv() 2021-08-02 15:13:15 +01:00
tag_ksz.c net/dsa/tag_ksz.c: remove superfluous headers 2021-09-29 11:38:21 +01:00
tag_lan9303.c net: dsa: create a helper for locating EtherType DSA headers on TX 2021-08-11 14:44:58 +01:00
tag_mtk.c net: dsa: create a helper for locating EtherType DSA headers on TX 2021-08-11 14:44:58 +01:00
tag_ocelot_8021q.c net: dsa: make tagging protocols connect to individual switches from a tree 2021-12-14 12:45:16 +00:00
tag_ocelot.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-12-23 16:09:58 -08:00
tag_qca.c net: dsa: create a helper for locating EtherType DSA headers on TX 2021-08-11 14:44:58 +01:00
tag_rtl4_a.c net: dsa: tag_rtl4_a: Drop bit 9 from egress frames 2021-09-14 19:34:03 -07:00
tag_rtl8_4.c net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag 2021-10-18 14:02:56 +01:00
tag_sja1105.c net: dsa: make tagging protocols connect to individual switches from a tree 2021-12-14 12:45:16 +00:00
tag_trailer.c net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv() 2021-08-02 15:13:15 +01:00
tag_xrs700x.c net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv() 2021-08-02 15:13:15 +01:00