linux/net/dsa
Vladimir Oltean 4e4ab79500 net: dsa: calculate the largest_mtu across all ports in the tree
If we have a cross-chip topology like this:

   sw0p0     sw0p1     sw0p2     sw0p3     sw0p4
[  cpu  ] [  user ] [  user ] [  dsa  ] [  user ]
                                  |
                                  +---------+
                                            |
   sw1p0     sw1p1     sw1p2     sw1p3     sw1p4
[  user ] [  user ] [  user ] [  dsa  ] [  dsa  ]

and we issue the following commands:

1. ip link set sw0p1 mtu 1700
2. ip link set sw1p1 mtu 1600

we notice the following happening:

Command 1. emits a non-targeted MTU notifier for the CPU port (sw0p0)
with the largest_mtu calculated across switch 0, of 1700. This matches
sw0p0, sw0p3 and sw1p4 (all CPU ports and DSA links).
Then, it emits a targeted MTU notifier for the user port (sw0p1), again
with MTU 1700 (this doesn't matter).

Command 2. emits a non-targeted MTU notifier for the CPU port (sw0p0)
with the largest_mtu calculated across switch 1, of 1600. This matches
the same group of ports as above, and decreases the MTU for the CPU port
and the DSA links from 1700 to 1600.

As a result, the sw0p1 user port can no longer communicate with its CPU
port at MTU 1700.

To address this, we should calculate the largest_mtu across all switches
that may share a CPU port, and only emit MTU notifiers with that value.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-06-21 12:50:20 -07:00
..
dsa2.c net: dsa: export the dsa_port_is_{user,cpu,dsa} helpers 2021-06-21 12:50:20 -07:00
dsa_priv.h net: dsa: generalize overhead for taggers that use both headers and trailers 2021-06-11 12:45:38 -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: selftest: fix build issue if INET is disabled 2021-04-28 14:06:45 -07:00
Makefile net: dsa: add a second tagger for Ocelot switches based on tag_8021q 2021-01-29 21:25:27 -08:00
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: fix bridge support for drivers without port_bridge_flags callback 2021-04-21 10:47:27 -07:00
slave.c net: dsa: calculate the largest_mtu across all ports in the tree 2021-06-21 12:50:20 -07:00
switch.c net: dsa: execute dsa_switch_mdb_add only for routing port in cross-chip topologies 2021-06-21 12:50:20 -07:00
tag_8021q.c net: dsa: tag_8021q: refactor RX VLAN parsing into a dedicated function 2021-06-11 12:45:38 -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: tag_8021q: refactor RX VLAN parsing into a dedicated function 2021-06-11 12:45:38 -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: implement TX timestamping for SJA1110 2021-06-11 12:45:38 -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