linux/net/dsa
Vladimir Oltean d7b1fd520d net: dsa: let the core manage the tag_8021q context
The basic problem description is as follows:

Be there 3 switches in a daisy chain topology:

                                             |
    sw0p0     sw0p1     sw0p2     sw0p3     sw0p4
 [  user ] [  user ] [  user ] [  dsa  ] [  cpu  ]
                                   |
                                   +---------+
                                             |
    sw1p0     sw1p1     sw1p2     sw1p3     sw1p4
 [  user ] [  user ] [  user ] [  dsa  ] [  dsa  ]
                                   |
                                   +---------+
                                             |
    sw2p0     sw2p1     sw2p2     sw2p3     sw2p4
 [  user ] [  user ] [  user ] [  user ] [  dsa  ]

The CPU will not be able to ping through the user ports of the
bottom-most switch (like for example sw2p0), simply because tag_8021q
was not coded up for this scenario - it has always assumed DSA switch
trees with a single switch.

To add support for the topology above, we must admit that the RX VLAN of
sw2p0 must be added on some ports of switches 0 and 1 as well. This is
in fact a textbook example of thing that can use the cross-chip notifier
framework that DSA has set up in switch.c.

There is only one problem: core DSA (switch.c) is not able right now to
make the connection between a struct dsa_switch *ds and a struct
dsa_8021q_context *ctx. Right now, it is drivers who call into
tag_8021q.c and always provide a struct dsa_8021q_context *ctx pointer,
and tag_8021q.c calls them back with the .tag_8021q_vlan_{add,del}
methods.

But with cross-chip notifiers, it is possible for tag_8021q to call
drivers without drivers having ever asked for anything. A good example
is right above: when sw2p0 wants to set itself up for tag_8021q,
the .tag_8021q_vlan_add method needs to be called for switches 1 and 0,
so that they transport sw2p0's VLANs towards the CPU without dropping
them.

So instead of letting drivers manage the tag_8021q context, add a
tag_8021q_ctx pointer inside of struct dsa_switch, which will be
populated when dsa_tag_8021q_register() returns success.

The patch is fairly long-winded because we are partly reverting commit
5899ee367a ("net: dsa: tag_8021q: add a context structure") which made
the driver-facing tag_8021q API use "ctx" instead of "ds". Now that we
can access "ctx" directly from "ds", this is no longer needed.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-20 06:36:42 -07:00
..
dsa2.c net: dsa: reference count the FDB addresses at the cross-chip notifier level 2021-06-29 10:46:23 -07:00
dsa_priv.h net: dsa: ensure during dsa_fdb_offload_notify that dev_hold and dev_put are on the same dev 2021-06-29 10:46:23 -07:00
dsa.c net: dsa: allow changing the tag protocol via the "tagging" device attribute 2021-01-29 21:24:39 -08:00
Kconfig net: dsa: build tag_8021q.c as part of DSA core 2021-07-20 06:36:42 -07:00
Makefile net: dsa: build tag_8021q.c as part of DSA core 2021-07-20 06:36:42 -07:00
master.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
port.c net: dsa: replay the local bridge FDB entries pointing to the bridge dev too 2021-06-29 10:46:23 -07:00
slave.c net: dsa: ensure during dsa_fdb_offload_notify that dev_hold and dev_put are on the same dev 2021-06-29 10:46:23 -07:00
switch.c net: dsa: properly check for the bridge_leave methods in dsa_switch_bridge_leave() 2021-07-13 14:47:10 -07:00
tag_8021q.c net: dsa: let the core manage the tag_8021q context 2021-07-20 06:36:42 -07:00
tag_ar9331.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_brcm.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_dsa.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_gswip.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_hellcreek.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_ksz.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_lan9303.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_mtk.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_ocelot_8021q.c net: dsa: sja1105: delete the best_effort_vlan_filtering mode 2021-07-20 06:36:42 -07:00
tag_ocelot.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_qca.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_rtl4_a.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_sja1105.c net: dsa: sja1105: delete the best_effort_vlan_filtering mode 2021-07-20 06:36:42 -07:00
tag_trailer.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00
tag_xrs700x.c net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -07:00