net: dsa: Optional VLAN-based port separation for switches without tagging
This patch provides generic DSA code for using VLAN (802.1Q) tags for
the same purpose as a dedicated switch tag for injection/extraction.
It is based on the discussions and interest that has been so far
expressed in https://www.spinics.net/lists/netdev/msg556125.html.
Unlike all other DSA-supported tagging protocols, CONFIG_NET_DSA_TAG_8021Q
does not offer a complete solution for drivers (nor can it). Instead, it
provides generic code that driver can opt into calling:
- dsa_8021q_xmit: Inserts a VLAN header with the specified contents.
Can be called from another tagging protocol's xmit function.
Currently the LAN9303 driver is inserting headers that are simply
802.1Q with custom fields, so this is an opportunity for code reuse.
- dsa_8021q_rcv: Retrieves the TPID and TCI from a VLAN-tagged skb.
Removing the VLAN header is left as a decision for the caller to make.
- dsa_port_setup_8021q_tagging: For each user port, installs an Rx VID
and a Tx VID, for proper untagged traffic identification on ingress
and steering on egress. Also sets up the VLAN trunk on the upstream
(CPU or DSA) port. Drivers are intentionally left to call this
function explicitly, depending on the context and hardware support.
The expected switch behavior and VLAN semantics should not be violated
under any conditions. That is, after calling
dsa_port_setup_8021q_tagging, the hardware should still pass all
ingress traffic, be it tagged or untagged.
For uniformity with the other tagging protocols, a module for the
dsa_8021q_netdev_ops structure is registered, but the typical usage is
to set up another tagging protocol which selects CONFIG_NET_DSA_TAG_8021Q,
and calls the API from tag_8021q.h. Null function definitions are also
provided so that a "depends on" is not forced in the Kconfig.
This tagging protocol only works when switch ports are standalone, or
when they are added to a VLAN-unaware bridge. It will probably remain
this way for the reasons below.
When added to a bridge that has vlan_filtering 1, the bridge core will
install its own VLANs and reset the pvids through switchdev. For the
bridge core, switchdev is a write-only pipe. All VLAN-related state is
kept in the bridge core and nothing is read from DSA/switchdev or from
the driver. So the bridge core will break this port separation because
it will install the vlan_default_pvid into all switchdev ports.
Even if we could teach the bridge driver about switchdev preference of a
certain vlan_default_pvid (task difficult in itself since the current
setting is per-bridge but we would need it per-port), there would still
exist many other challenges.
Firstly, in the DSA rcv callback, a driver would have to perform an
iterative reverse lookup to find the correct switch port. That is
because the port is a bridge slave, so its Rx VID (port PVID) is subject
to user configuration. How would we ensure that the user doesn't reset
the pvid to a different value (which would make an O(1) translation
impossible), or to a non-unique value within this DSA switch tree (which
would make any translation impossible)?
Finally, not all switch ports are equal in DSA, and that makes it
difficult for the bridge to be completely aware of this anyway.
The CPU port needs to transmit tagged packets (VLAN trunk) in order for
the DSA rcv code to be able to decode source information.
But the bridge code has absolutely no idea which switch port is the CPU
port, if nothing else then just because there is no netdevice registered
by DSA for the CPU port.
Also DSA does not currently allow the user to specify that they want the
CPU port to do VLAN trunking anyway. VLANs are added to the CPU port
using the same flags as they were added on the user port.
So the VLANs installed by dsa_port_setup_8021q_tagging per driver
request should remain private from the bridge's and user's perspective,
and should not alter the VLAN semantics observed by the user.
In the current implementation a VLAN range ending at 4095 (VLAN_N_VID)
is reserved for this purpose. Each port receives a unique Rx VLAN and a
unique Tx VLAN. Separate VLANs are needed for Rx and Tx because they
serve different purposes: on Rx the switch must process traffic as
untagged and process it with a port-based VLAN, but with care not to
hinder bridging. On the other hand, the Tx VLAN is where the
reachability restrictions are imposed, since by tagging frames in the
xmit callback we are telling the switch onto which port to steer the
frame.
Some general guidance on how this support might be employed for
real-life hardware (some comments made by Florian Fainelli):
- If the hardware supports VLAN tag stacking, it should somehow back
up its private VLAN settings when the bridge tries to override them.
Then the driver could re-apply them as outer tags. Dedicating an outer
tag per bridge device would allow identical inner tag VID numbers to
co-exist, yet preserve broadcast domain isolation.
- If the switch cannot handle VLAN tag stacking, it should disable this
port separation when added as slave to a vlan_filtering bridge, in
that case having reduced functionality.
- Drivers for old switches that don't support the entire VLAN_N_VID
range will need to rework the current range selection mechanism.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-05 18:19:22 +08:00
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/* SPDX-License-Identifier: GPL-2.0
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* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
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*/
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#ifndef _NET_DSA_8021Q_H
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#define _NET_DSA_8021Q_H
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2020-09-11 00:48:54 +08:00
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#include <linux/refcount.h>
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net: dsa: Optional VLAN-based port separation for switches without tagging
This patch provides generic DSA code for using VLAN (802.1Q) tags for
the same purpose as a dedicated switch tag for injection/extraction.
It is based on the discussions and interest that has been so far
expressed in https://www.spinics.net/lists/netdev/msg556125.html.
Unlike all other DSA-supported tagging protocols, CONFIG_NET_DSA_TAG_8021Q
does not offer a complete solution for drivers (nor can it). Instead, it
provides generic code that driver can opt into calling:
- dsa_8021q_xmit: Inserts a VLAN header with the specified contents.
Can be called from another tagging protocol's xmit function.
Currently the LAN9303 driver is inserting headers that are simply
802.1Q with custom fields, so this is an opportunity for code reuse.
- dsa_8021q_rcv: Retrieves the TPID and TCI from a VLAN-tagged skb.
Removing the VLAN header is left as a decision for the caller to make.
- dsa_port_setup_8021q_tagging: For each user port, installs an Rx VID
and a Tx VID, for proper untagged traffic identification on ingress
and steering on egress. Also sets up the VLAN trunk on the upstream
(CPU or DSA) port. Drivers are intentionally left to call this
function explicitly, depending on the context and hardware support.
The expected switch behavior and VLAN semantics should not be violated
under any conditions. That is, after calling
dsa_port_setup_8021q_tagging, the hardware should still pass all
ingress traffic, be it tagged or untagged.
For uniformity with the other tagging protocols, a module for the
dsa_8021q_netdev_ops structure is registered, but the typical usage is
to set up another tagging protocol which selects CONFIG_NET_DSA_TAG_8021Q,
and calls the API from tag_8021q.h. Null function definitions are also
provided so that a "depends on" is not forced in the Kconfig.
This tagging protocol only works when switch ports are standalone, or
when they are added to a VLAN-unaware bridge. It will probably remain
this way for the reasons below.
When added to a bridge that has vlan_filtering 1, the bridge core will
install its own VLANs and reset the pvids through switchdev. For the
bridge core, switchdev is a write-only pipe. All VLAN-related state is
kept in the bridge core and nothing is read from DSA/switchdev or from
the driver. So the bridge core will break this port separation because
it will install the vlan_default_pvid into all switchdev ports.
Even if we could teach the bridge driver about switchdev preference of a
certain vlan_default_pvid (task difficult in itself since the current
setting is per-bridge but we would need it per-port), there would still
exist many other challenges.
Firstly, in the DSA rcv callback, a driver would have to perform an
iterative reverse lookup to find the correct switch port. That is
because the port is a bridge slave, so its Rx VID (port PVID) is subject
to user configuration. How would we ensure that the user doesn't reset
the pvid to a different value (which would make an O(1) translation
impossible), or to a non-unique value within this DSA switch tree (which
would make any translation impossible)?
Finally, not all switch ports are equal in DSA, and that makes it
difficult for the bridge to be completely aware of this anyway.
The CPU port needs to transmit tagged packets (VLAN trunk) in order for
the DSA rcv code to be able to decode source information.
But the bridge code has absolutely no idea which switch port is the CPU
port, if nothing else then just because there is no netdevice registered
by DSA for the CPU port.
Also DSA does not currently allow the user to specify that they want the
CPU port to do VLAN trunking anyway. VLANs are added to the CPU port
using the same flags as they were added on the user port.
So the VLANs installed by dsa_port_setup_8021q_tagging per driver
request should remain private from the bridge's and user's perspective,
and should not alter the VLAN semantics observed by the user.
In the current implementation a VLAN range ending at 4095 (VLAN_N_VID)
is reserved for this purpose. Each port receives a unique Rx VLAN and a
unique Tx VLAN. Separate VLANs are needed for Rx and Tx because they
serve different purposes: on Rx the switch must process traffic as
untagged and process it with a port-based VLAN, but with care not to
hinder bridging. On the other hand, the Tx VLAN is where the
reachability restrictions are imposed, since by tagging frames in the
xmit callback we are telling the switch onto which port to steer the
frame.
Some general guidance on how this support might be employed for
real-life hardware (some comments made by Florian Fainelli):
- If the hardware supports VLAN tag stacking, it should somehow back
up its private VLAN settings when the bridge tries to override them.
Then the driver could re-apply them as outer tags. Dedicating an outer
tag per bridge device would allow identical inner tag VID numbers to
co-exist, yet preserve broadcast domain isolation.
- If the switch cannot handle VLAN tag stacking, it should disable this
port separation when added as slave to a vlan_filtering bridge, in
that case having reduced functionality.
- Drivers for old switches that don't support the entire VLAN_N_VID
range will need to rework the current range selection mechanism.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-05 18:19:22 +08:00
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#include <linux/types.h>
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struct dsa_switch;
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struct sk_buff;
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struct net_device;
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net: dsa: tag_8021q: add proper cross-chip notifier support
The big problem which mandates cross-chip notifiers for tag_8021q is
this:
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sw0p0 sw0p1 sw0p2 sw0p3 sw0p4
[ user ] [ user ] [ user ] [ dsa ] [ cpu ]
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+---------+
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sw1p0 sw1p1 sw1p2 sw1p3 sw1p4
[ user ] [ user ] [ user ] [ dsa ] [ dsa ]
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+---------+
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sw2p0 sw2p1 sw2p2 sw2p3 sw2p4
[ user ] [ user ] [ user ] [ dsa ] [ dsa ]
When the user runs:
ip link add br0 type bridge
ip link set sw0p0 master br0
ip link set sw2p0 master br0
It doesn't work.
This is because dsa_8021q_crosschip_bridge_join() assumes that "ds" and
"other_ds" are at most 1 hop away from each other, so it is sufficient
to add the RX VLAN of {ds, port} into {other_ds, other_port} and vice
versa and presto, the cross-chip link works. When there is another
switch in the middle, such as in this case switch 1 with its DSA links
sw1p3 and sw1p4, somebody needs to tell it about these VLANs too.
Which is exactly why the problem is quadratic: when a port joins a
bridge, for each port in the tree that's already in that same bridge we
notify a tag_8021q VLAN addition of that port's RX VLAN to the entire
tree. It is a very complicated web of VLANs.
It must be mentioned that currently we install tag_8021q VLANs on too
many ports (DSA links - to be precise, on all of them). For example,
when sw2p0 joins br0, and assuming sw1p0 was part of br0 too, we add the
RX VLAN of sw2p0 on the DSA links of switch 0 too, even though there
isn't any port of switch 0 that is a member of br0 (at least yet).
In theory we could notify only the switches which sit in between the
port joining the bridge and the port reacting to that bridge_join event.
But in practice that is impossible, because of the way 'link' properties
are described in the device tree. The DSA bindings require DT writers to
list out not only the real/physical DSA links, but in fact the entire
routing table, like for example switch 0 above will have:
sw0p3: port@3 {
link = <&sw1p4 &sw2p4>;
};
This was done because:
/* TODO: ideally DSA ports would have a single dp->link_dp member,
* and no dst->rtable nor this struct dsa_link would be needed,
* but this would require some more complex tree walking,
* so keep it stupid at the moment and list them all.
*/
but it is a perfect example of a situation where too much information is
actively detrimential, because we are now in the position where we
cannot distinguish a real DSA link from one that is put there to avoid
the 'complex tree walking'. And because DT is ABI, there is not much we
can change.
And because we do not know which DSA links are real and which ones
aren't, we can't really know if DSA switch A is in the data path between
switches B and C, in the general case.
So this is why tag_8021q RX VLANs are added on all DSA links, and
probably why it will never change.
On the other hand, at least the number of additions/deletions is well
balanced, and this means that once we implement reference counting at
the cross-chip notifier level a la fdb/mdb, there is absolutely zero
need for a struct dsa_8021q_crosschip_link, it's all self-managing.
In fact, with the tag_8021q notifiers emitted from the bridge join
notifiers, it becomes so generic that sja1105 does not need to do
anything anymore, we can just delete its implementation of the
.crosschip_bridge_{join,leave} methods.
Among other things we can simply delete is the home-grown implementation
of sja1105_notify_crosschip_switches(). The reason why that is wrong is
because it is not quadratic - it only covers remote switches to which we
have a cross-chip bridging link and that does not cover in-between
switches. This deletion is part of the same patch because sja1105 used
to poke deep inside the guts of the tag_8021q context in order to do
that. Because the cross-chip links went away, so needs the sja1105 code.
Last but not least, dsa_8021q_setup_port() is simplified (and also
renamed). Because our TAG_8021Q_VLAN_ADD notifier is designed to react
on the CPU port too, the four dsa_8021q_vid_apply() calls:
- 1 for RX VLAN on user port
- 1 for the user port's RX VLAN on the CPU port
- 1 for TX VLAN on user port
- 1 for the user port's TX VLAN on the CPU port
now get squashed into only 2 notifier calls via
dsa_port_tag_8021q_vlan_add.
And because the notifiers to add and to delete a tag_8021q VLAN are
distinct, now we finally break up the port setup and teardown into
separate functions instead of relying on a "bool enabled" flag which
tells us what to do. Arguably it should have been this way from the
get go.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-20 01:14:52 +08:00
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struct dsa_tag_8021q_vlan {
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net: dsa: sja1105: implement cross-chip bridging operations
sja1105 uses dsa_8021q for DSA tagging, a format which is VLAN at heart
and which is compatible with cascading. A complete description of this
tagging format is in net/dsa/tag_8021q.c, but a quick summary is that
each external-facing port tags incoming frames with a unique pvid, and
this special VLAN is transmitted as tagged towards the inside of the
system, and as untagged towards the exterior. The tag encodes the switch
id and the source port index.
This means that cross-chip bridging for dsa_8021q only entails adding
the dsa_8021q pvids of one switch to the RX filter of the other
switches. Everything else falls naturally into place, as long as the
bottom-end of ports (the leaves in the tree) is comprised exclusively of
dsa_8021q-compatible (i.e. sja1105 switches). Otherwise, there would be
a chance that a front-panel switch transmits a packet tagged with a
dsa_8021q header, header which it wouldn't be able to remove, and which
would hence "leak" out.
The only use case I tested (due to lack of board availability) was when
the sja1105 switches are part of disjoint trees (however, this doesn't
change the fact that multiple sja1105 switches still need unique switch
identifiers in such a system). But in principle, even "true" single-tree
setups (with DSA links) should work just as fine, except for a small
change which I can't test: dsa_towards_port should be used instead of
dsa_upstream_port (I made the assumption that the routing port that any
sja1105 should use towards its neighbours is the CPU port. That might
not hold true in other setups).
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2020-05-11 00:37:43 +08:00
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struct list_head list;
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int port;
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net: dsa: tag_8021q: add proper cross-chip notifier support
The big problem which mandates cross-chip notifiers for tag_8021q is
this:
|
sw0p0 sw0p1 sw0p2 sw0p3 sw0p4
[ user ] [ user ] [ user ] [ dsa ] [ cpu ]
|
+---------+
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sw1p0 sw1p1 sw1p2 sw1p3 sw1p4
[ user ] [ user ] [ user ] [ dsa ] [ dsa ]
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+---------+
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sw2p0 sw2p1 sw2p2 sw2p3 sw2p4
[ user ] [ user ] [ user ] [ dsa ] [ dsa ]
When the user runs:
ip link add br0 type bridge
ip link set sw0p0 master br0
ip link set sw2p0 master br0
It doesn't work.
This is because dsa_8021q_crosschip_bridge_join() assumes that "ds" and
"other_ds" are at most 1 hop away from each other, so it is sufficient
to add the RX VLAN of {ds, port} into {other_ds, other_port} and vice
versa and presto, the cross-chip link works. When there is another
switch in the middle, such as in this case switch 1 with its DSA links
sw1p3 and sw1p4, somebody needs to tell it about these VLANs too.
Which is exactly why the problem is quadratic: when a port joins a
bridge, for each port in the tree that's already in that same bridge we
notify a tag_8021q VLAN addition of that port's RX VLAN to the entire
tree. It is a very complicated web of VLANs.
It must be mentioned that currently we install tag_8021q VLANs on too
many ports (DSA links - to be precise, on all of them). For example,
when sw2p0 joins br0, and assuming sw1p0 was part of br0 too, we add the
RX VLAN of sw2p0 on the DSA links of switch 0 too, even though there
isn't any port of switch 0 that is a member of br0 (at least yet).
In theory we could notify only the switches which sit in between the
port joining the bridge and the port reacting to that bridge_join event.
But in practice that is impossible, because of the way 'link' properties
are described in the device tree. The DSA bindings require DT writers to
list out not only the real/physical DSA links, but in fact the entire
routing table, like for example switch 0 above will have:
sw0p3: port@3 {
link = <&sw1p4 &sw2p4>;
};
This was done because:
/* TODO: ideally DSA ports would have a single dp->link_dp member,
* and no dst->rtable nor this struct dsa_link would be needed,
* but this would require some more complex tree walking,
* so keep it stupid at the moment and list them all.
*/
but it is a perfect example of a situation where too much information is
actively detrimential, because we are now in the position where we
cannot distinguish a real DSA link from one that is put there to avoid
the 'complex tree walking'. And because DT is ABI, there is not much we
can change.
And because we do not know which DSA links are real and which ones
aren't, we can't really know if DSA switch A is in the data path between
switches B and C, in the general case.
So this is why tag_8021q RX VLANs are added on all DSA links, and
probably why it will never change.
On the other hand, at least the number of additions/deletions is well
balanced, and this means that once we implement reference counting at
the cross-chip notifier level a la fdb/mdb, there is absolutely zero
need for a struct dsa_8021q_crosschip_link, it's all self-managing.
In fact, with the tag_8021q notifiers emitted from the bridge join
notifiers, it becomes so generic that sja1105 does not need to do
anything anymore, we can just delete its implementation of the
.crosschip_bridge_{join,leave} methods.
Among other things we can simply delete is the home-grown implementation
of sja1105_notify_crosschip_switches(). The reason why that is wrong is
because it is not quadratic - it only covers remote switches to which we
have a cross-chip bridging link and that does not cover in-between
switches. This deletion is part of the same patch because sja1105 used
to poke deep inside the guts of the tag_8021q context in order to do
that. Because the cross-chip links went away, so needs the sja1105 code.
Last but not least, dsa_8021q_setup_port() is simplified (and also
renamed). Because our TAG_8021Q_VLAN_ADD notifier is designed to react
on the CPU port too, the four dsa_8021q_vid_apply() calls:
- 1 for RX VLAN on user port
- 1 for the user port's RX VLAN on the CPU port
- 1 for TX VLAN on user port
- 1 for the user port's TX VLAN on the CPU port
now get squashed into only 2 notifier calls via
dsa_port_tag_8021q_vlan_add.
And because the notifiers to add and to delete a tag_8021q VLAN are
distinct, now we finally break up the port setup and teardown into
separate functions instead of relying on a "bool enabled" flag which
tells us what to do. Arguably it should have been this way from the
get go.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-20 01:14:52 +08:00
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u16 vid;
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net: dsa: sja1105: implement cross-chip bridging operations
sja1105 uses dsa_8021q for DSA tagging, a format which is VLAN at heart
and which is compatible with cascading. A complete description of this
tagging format is in net/dsa/tag_8021q.c, but a quick summary is that
each external-facing port tags incoming frames with a unique pvid, and
this special VLAN is transmitted as tagged towards the inside of the
system, and as untagged towards the exterior. The tag encodes the switch
id and the source port index.
This means that cross-chip bridging for dsa_8021q only entails adding
the dsa_8021q pvids of one switch to the RX filter of the other
switches. Everything else falls naturally into place, as long as the
bottom-end of ports (the leaves in the tree) is comprised exclusively of
dsa_8021q-compatible (i.e. sja1105 switches). Otherwise, there would be
a chance that a front-panel switch transmits a packet tagged with a
dsa_8021q header, header which it wouldn't be able to remove, and which
would hence "leak" out.
The only use case I tested (due to lack of board availability) was when
the sja1105 switches are part of disjoint trees (however, this doesn't
change the fact that multiple sja1105 switches still need unique switch
identifiers in such a system). But in principle, even "true" single-tree
setups (with DSA links) should work just as fine, except for a small
change which I can't test: dsa_towards_port should be used instead of
dsa_upstream_port (I made the assumption that the routing port that any
sja1105 should use towards its neighbours is the CPU port. That might
not hold true in other setups).
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2020-05-11 00:37:43 +08:00
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refcount_t refcount;
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};
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net: dsa: tag_8021q: add a context structure
While working on another tag_8021q driver implementation, some things
became apparent:
- It is not mandatory for a DSA driver to offload the tag_8021q VLANs by
using the VLAN table per se. For example, it can add custom TCAM rules
that simply encapsulate RX traffic, and redirect & decapsulate rules
for TX traffic. For such a driver, it makes no sense to receive the
tag_8021q configuration through the same callback as it receives the
VLAN configuration from the bridge and the 8021q modules.
- Currently, sja1105 (the only tag_8021q user) sets a
priv->expect_dsa_8021q variable to distinguish between the bridge
calling, and tag_8021q calling. That can be improved, to say the
least.
- The crosschip bridging operations are, in fact, stateful already. The
list of crosschip_links must be kept by the caller and passed to the
relevant tag_8021q functions.
So it would be nice if the tag_8021q configuration was more
self-contained. This patch attempts to do that.
Create a struct dsa_8021q_context which encapsulates a struct
dsa_switch, and has 2 function pointers for adding and deleting a VLAN.
These will replace the previous channel to the driver, which was through
the .port_vlan_add and .port_vlan_del callbacks of dsa_switch_ops.
Also put the list of crosschip_links into this dsa_8021q_context.
Drivers that don't support cross-chip bridging can simply omit to
initialize this list, as long as they dont call any cross-chip function.
The sja1105_vlan_add and sja1105_vlan_del functions are refactored into
a smaller sja1105_vlan_add_one, which now has 2 entry points:
- sja1105_vlan_add, from struct dsa_switch_ops
- sja1105_dsa_8021q_vlan_add, from the tag_8021q ops
But even this change is fairly trivial. It just reflects the fact that
for sja1105, the VLANs from these 2 channels end up in the same hardware
table. However that is not necessarily true in the general sense (and
that's the reason for making this change).
The rest of the patch is mostly plain refactoring of "ds" -> "ctx". The
dsa_8021q_context structure needs to be propagated because adding a VLAN
is now done through the ops function pointers inside of it.
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>
2020-09-11 00:48:56 +08:00
|
|
|
struct dsa_8021q_context {
|
|
|
|
|
struct dsa_switch *ds;
|
net: dsa: tag_8021q: add proper cross-chip notifier support
The big problem which mandates cross-chip notifiers for tag_8021q is
this:
|
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 ] [ dsa ] [ dsa ]
When the user runs:
ip link add br0 type bridge
ip link set sw0p0 master br0
ip link set sw2p0 master br0
It doesn't work.
This is because dsa_8021q_crosschip_bridge_join() assumes that "ds" and
"other_ds" are at most 1 hop away from each other, so it is sufficient
to add the RX VLAN of {ds, port} into {other_ds, other_port} and vice
versa and presto, the cross-chip link works. When there is another
switch in the middle, such as in this case switch 1 with its DSA links
sw1p3 and sw1p4, somebody needs to tell it about these VLANs too.
Which is exactly why the problem is quadratic: when a port joins a
bridge, for each port in the tree that's already in that same bridge we
notify a tag_8021q VLAN addition of that port's RX VLAN to the entire
tree. It is a very complicated web of VLANs.
It must be mentioned that currently we install tag_8021q VLANs on too
many ports (DSA links - to be precise, on all of them). For example,
when sw2p0 joins br0, and assuming sw1p0 was part of br0 too, we add the
RX VLAN of sw2p0 on the DSA links of switch 0 too, even though there
isn't any port of switch 0 that is a member of br0 (at least yet).
In theory we could notify only the switches which sit in between the
port joining the bridge and the port reacting to that bridge_join event.
But in practice that is impossible, because of the way 'link' properties
are described in the device tree. The DSA bindings require DT writers to
list out not only the real/physical DSA links, but in fact the entire
routing table, like for example switch 0 above will have:
sw0p3: port@3 {
link = <&sw1p4 &sw2p4>;
};
This was done because:
/* TODO: ideally DSA ports would have a single dp->link_dp member,
* and no dst->rtable nor this struct dsa_link would be needed,
* but this would require some more complex tree walking,
* so keep it stupid at the moment and list them all.
*/
but it is a perfect example of a situation where too much information is
actively detrimential, because we are now in the position where we
cannot distinguish a real DSA link from one that is put there to avoid
the 'complex tree walking'. And because DT is ABI, there is not much we
can change.
And because we do not know which DSA links are real and which ones
aren't, we can't really know if DSA switch A is in the data path between
switches B and C, in the general case.
So this is why tag_8021q RX VLANs are added on all DSA links, and
probably why it will never change.
On the other hand, at least the number of additions/deletions is well
balanced, and this means that once we implement reference counting at
the cross-chip notifier level a la fdb/mdb, there is absolutely zero
need for a struct dsa_8021q_crosschip_link, it's all self-managing.
In fact, with the tag_8021q notifiers emitted from the bridge join
notifiers, it becomes so generic that sja1105 does not need to do
anything anymore, we can just delete its implementation of the
.crosschip_bridge_{join,leave} methods.
Among other things we can simply delete is the home-grown implementation
of sja1105_notify_crosschip_switches(). The reason why that is wrong is
because it is not quadratic - it only covers remote switches to which we
have a cross-chip bridging link and that does not cover in-between
switches. This deletion is part of the same patch because sja1105 used
to poke deep inside the guts of the tag_8021q context in order to do
that. Because the cross-chip links went away, so needs the sja1105 code.
Last but not least, dsa_8021q_setup_port() is simplified (and also
renamed). Because our TAG_8021Q_VLAN_ADD notifier is designed to react
on the CPU port too, the four dsa_8021q_vid_apply() calls:
- 1 for RX VLAN on user port
- 1 for the user port's RX VLAN on the CPU port
- 1 for TX VLAN on user port
- 1 for the user port's TX VLAN on the CPU port
now get squashed into only 2 notifier calls via
dsa_port_tag_8021q_vlan_add.
And because the notifiers to add and to delete a tag_8021q VLAN are
distinct, now we finally break up the port setup and teardown into
separate functions instead of relying on a "bool enabled" flag which
tells us what to do. Arguably it should have been this way from the
get go.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-20 01:14:52 +08:00
|
|
|
struct list_head vlans;
|
2020-09-21 08:10:30 +08:00
|
|
|
/* EtherType of RX VID, used for filtering on master interface */
|
|
|
|
|
__be16 proto;
|
net: dsa: tag_8021q: add a context structure
While working on another tag_8021q driver implementation, some things
became apparent:
- It is not mandatory for a DSA driver to offload the tag_8021q VLANs by
using the VLAN table per se. For example, it can add custom TCAM rules
that simply encapsulate RX traffic, and redirect & decapsulate rules
for TX traffic. For such a driver, it makes no sense to receive the
tag_8021q configuration through the same callback as it receives the
VLAN configuration from the bridge and the 8021q modules.
- Currently, sja1105 (the only tag_8021q user) sets a
priv->expect_dsa_8021q variable to distinguish between the bridge
calling, and tag_8021q calling. That can be improved, to say the
least.
- The crosschip bridging operations are, in fact, stateful already. The
list of crosschip_links must be kept by the caller and passed to the
relevant tag_8021q functions.
So it would be nice if the tag_8021q configuration was more
self-contained. This patch attempts to do that.
Create a struct dsa_8021q_context which encapsulates a struct
dsa_switch, and has 2 function pointers for adding and deleting a VLAN.
These will replace the previous channel to the driver, which was through
the .port_vlan_add and .port_vlan_del callbacks of dsa_switch_ops.
Also put the list of crosschip_links into this dsa_8021q_context.
Drivers that don't support cross-chip bridging can simply omit to
initialize this list, as long as they dont call any cross-chip function.
The sja1105_vlan_add and sja1105_vlan_del functions are refactored into
a smaller sja1105_vlan_add_one, which now has 2 entry points:
- sja1105_vlan_add, from struct dsa_switch_ops
- sja1105_dsa_8021q_vlan_add, from the tag_8021q ops
But even this change is fairly trivial. It just reflects the fact that
for sja1105, the VLANs from these 2 channels end up in the same hardware
table. However that is not necessarily true in the general sense (and
that's the reason for making this change).
The rest of the patch is mostly plain refactoring of "ds" -> "ctx". The
dsa_8021q_context structure needs to be propagated because adding a VLAN
is now done through the ops function pointers inside of it.
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>
2020-09-11 00:48:56 +08:00
|
|
|
};
|
|
|
|
|
|
2021-07-20 01:14:49 +08:00
|
|
|
int dsa_tag_8021q_register(struct dsa_switch *ds, __be16 proto);
|
2021-07-20 01:14:46 +08:00
|
|
|
|
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
5899ee367ab3 ("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 01:14:48 +08:00
|
|
|
void dsa_tag_8021q_unregister(struct dsa_switch *ds);
|
2021-07-20 01:14:46 +08:00
|
|
|
|
net: dsa: Optional VLAN-based port separation for switches without tagging
This patch provides generic DSA code for using VLAN (802.1Q) tags for
the same purpose as a dedicated switch tag for injection/extraction.
It is based on the discussions and interest that has been so far
expressed in https://www.spinics.net/lists/netdev/msg556125.html.
Unlike all other DSA-supported tagging protocols, CONFIG_NET_DSA_TAG_8021Q
does not offer a complete solution for drivers (nor can it). Instead, it
provides generic code that driver can opt into calling:
- dsa_8021q_xmit: Inserts a VLAN header with the specified contents.
Can be called from another tagging protocol's xmit function.
Currently the LAN9303 driver is inserting headers that are simply
802.1Q with custom fields, so this is an opportunity for code reuse.
- dsa_8021q_rcv: Retrieves the TPID and TCI from a VLAN-tagged skb.
Removing the VLAN header is left as a decision for the caller to make.
- dsa_port_setup_8021q_tagging: For each user port, installs an Rx VID
and a Tx VID, for proper untagged traffic identification on ingress
and steering on egress. Also sets up the VLAN trunk on the upstream
(CPU or DSA) port. Drivers are intentionally left to call this
function explicitly, depending on the context and hardware support.
The expected switch behavior and VLAN semantics should not be violated
under any conditions. That is, after calling
dsa_port_setup_8021q_tagging, the hardware should still pass all
ingress traffic, be it tagged or untagged.
For uniformity with the other tagging protocols, a module for the
dsa_8021q_netdev_ops structure is registered, but the typical usage is
to set up another tagging protocol which selects CONFIG_NET_DSA_TAG_8021Q,
and calls the API from tag_8021q.h. Null function definitions are also
provided so that a "depends on" is not forced in the Kconfig.
This tagging protocol only works when switch ports are standalone, or
when they are added to a VLAN-unaware bridge. It will probably remain
this way for the reasons below.
When added to a bridge that has vlan_filtering 1, the bridge core will
install its own VLANs and reset the pvids through switchdev. For the
bridge core, switchdev is a write-only pipe. All VLAN-related state is
kept in the bridge core and nothing is read from DSA/switchdev or from
the driver. So the bridge core will break this port separation because
it will install the vlan_default_pvid into all switchdev ports.
Even if we could teach the bridge driver about switchdev preference of a
certain vlan_default_pvid (task difficult in itself since the current
setting is per-bridge but we would need it per-port), there would still
exist many other challenges.
Firstly, in the DSA rcv callback, a driver would have to perform an
iterative reverse lookup to find the correct switch port. That is
because the port is a bridge slave, so its Rx VID (port PVID) is subject
to user configuration. How would we ensure that the user doesn't reset
the pvid to a different value (which would make an O(1) translation
impossible), or to a non-unique value within this DSA switch tree (which
would make any translation impossible)?
Finally, not all switch ports are equal in DSA, and that makes it
difficult for the bridge to be completely aware of this anyway.
The CPU port needs to transmit tagged packets (VLAN trunk) in order for
the DSA rcv code to be able to decode source information.
But the bridge code has absolutely no idea which switch port is the CPU
port, if nothing else then just because there is no netdevice registered
by DSA for the CPU port.
Also DSA does not currently allow the user to specify that they want the
CPU port to do VLAN trunking anyway. VLANs are added to the CPU port
using the same flags as they were added on the user port.
So the VLANs installed by dsa_port_setup_8021q_tagging per driver
request should remain private from the bridge's and user's perspective,
and should not alter the VLAN semantics observed by the user.
In the current implementation a VLAN range ending at 4095 (VLAN_N_VID)
is reserved for this purpose. Each port receives a unique Rx VLAN and a
unique Tx VLAN. Separate VLANs are needed for Rx and Tx because they
serve different purposes: on Rx the switch must process traffic as
untagged and process it with a port-based VLAN, but with care not to
hinder bridging. On the other hand, the Tx VLAN is where the
reachability restrictions are imposed, since by tagging frames in the
xmit callback we are telling the switch onto which port to steer the
frame.
Some general guidance on how this support might be employed for
real-life hardware (some comments made by Florian Fainelli):
- If the hardware supports VLAN tag stacking, it should somehow back
up its private VLAN settings when the bridge tries to override them.
Then the driver could re-apply them as outer tags. Dedicating an outer
tag per bridge device would allow identical inner tag VID numbers to
co-exist, yet preserve broadcast domain isolation.
- If the switch cannot handle VLAN tag stacking, it should disable this
port separation when added as slave to a vlan_filtering bridge, in
that case having reduced functionality.
- Drivers for old switches that don't support the entire VLAN_N_VID
range will need to rework the current range selection mechanism.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-05 18:19:22 +08:00
|
|
|
struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev,
|
|
|
|
|
u16 tpid, u16 tci);
|
|
|
|
|
|
2021-07-20 01:14:42 +08:00
|
|
|
void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id);
|
2021-06-12 03:01:27 +08:00
|
|
|
|
net: dsa: Optional VLAN-based port separation for switches without tagging
This patch provides generic DSA code for using VLAN (802.1Q) tags for
the same purpose as a dedicated switch tag for injection/extraction.
It is based on the discussions and interest that has been so far
expressed in https://www.spinics.net/lists/netdev/msg556125.html.
Unlike all other DSA-supported tagging protocols, CONFIG_NET_DSA_TAG_8021Q
does not offer a complete solution for drivers (nor can it). Instead, it
provides generic code that driver can opt into calling:
- dsa_8021q_xmit: Inserts a VLAN header with the specified contents.
Can be called from another tagging protocol's xmit function.
Currently the LAN9303 driver is inserting headers that are simply
802.1Q with custom fields, so this is an opportunity for code reuse.
- dsa_8021q_rcv: Retrieves the TPID and TCI from a VLAN-tagged skb.
Removing the VLAN header is left as a decision for the caller to make.
- dsa_port_setup_8021q_tagging: For each user port, installs an Rx VID
and a Tx VID, for proper untagged traffic identification on ingress
and steering on egress. Also sets up the VLAN trunk on the upstream
(CPU or DSA) port. Drivers are intentionally left to call this
function explicitly, depending on the context and hardware support.
The expected switch behavior and VLAN semantics should not be violated
under any conditions. That is, after calling
dsa_port_setup_8021q_tagging, the hardware should still pass all
ingress traffic, be it tagged or untagged.
For uniformity with the other tagging protocols, a module for the
dsa_8021q_netdev_ops structure is registered, but the typical usage is
to set up another tagging protocol which selects CONFIG_NET_DSA_TAG_8021Q,
and calls the API from tag_8021q.h. Null function definitions are also
provided so that a "depends on" is not forced in the Kconfig.
This tagging protocol only works when switch ports are standalone, or
when they are added to a VLAN-unaware bridge. It will probably remain
this way for the reasons below.
When added to a bridge that has vlan_filtering 1, the bridge core will
install its own VLANs and reset the pvids through switchdev. For the
bridge core, switchdev is a write-only pipe. All VLAN-related state is
kept in the bridge core and nothing is read from DSA/switchdev or from
the driver. So the bridge core will break this port separation because
it will install the vlan_default_pvid into all switchdev ports.
Even if we could teach the bridge driver about switchdev preference of a
certain vlan_default_pvid (task difficult in itself since the current
setting is per-bridge but we would need it per-port), there would still
exist many other challenges.
Firstly, in the DSA rcv callback, a driver would have to perform an
iterative reverse lookup to find the correct switch port. That is
because the port is a bridge slave, so its Rx VID (port PVID) is subject
to user configuration. How would we ensure that the user doesn't reset
the pvid to a different value (which would make an O(1) translation
impossible), or to a non-unique value within this DSA switch tree (which
would make any translation impossible)?
Finally, not all switch ports are equal in DSA, and that makes it
difficult for the bridge to be completely aware of this anyway.
The CPU port needs to transmit tagged packets (VLAN trunk) in order for
the DSA rcv code to be able to decode source information.
But the bridge code has absolutely no idea which switch port is the CPU
port, if nothing else then just because there is no netdevice registered
by DSA for the CPU port.
Also DSA does not currently allow the user to specify that they want the
CPU port to do VLAN trunking anyway. VLANs are added to the CPU port
using the same flags as they were added on the user port.
So the VLANs installed by dsa_port_setup_8021q_tagging per driver
request should remain private from the bridge's and user's perspective,
and should not alter the VLAN semantics observed by the user.
In the current implementation a VLAN range ending at 4095 (VLAN_N_VID)
is reserved for this purpose. Each port receives a unique Rx VLAN and a
unique Tx VLAN. Separate VLANs are needed for Rx and Tx because they
serve different purposes: on Rx the switch must process traffic as
untagged and process it with a port-based VLAN, but with care not to
hinder bridging. On the other hand, the Tx VLAN is where the
reachability restrictions are imposed, since by tagging frames in the
xmit callback we are telling the switch onto which port to steer the
frame.
Some general guidance on how this support might be employed for
real-life hardware (some comments made by Florian Fainelli):
- If the hardware supports VLAN tag stacking, it should somehow back
up its private VLAN settings when the bridge tries to override them.
Then the driver could re-apply them as outer tags. Dedicating an outer
tag per bridge device would allow identical inner tag VID numbers to
co-exist, yet preserve broadcast domain isolation.
- If the switch cannot handle VLAN tag stacking, it should disable this
port separation when added as slave to a vlan_filtering bridge, in
that case having reduced functionality.
- Drivers for old switches that don't support the entire VLAN_N_VID
range will need to rework the current range selection mechanism.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-05 18:19:22 +08:00
|
|
|
u16 dsa_8021q_tx_vid(struct dsa_switch *ds, int port);
|
|
|
|
|
|
|
|
|
|
u16 dsa_8021q_rx_vid(struct dsa_switch *ds, int port);
|
|
|
|
|
|
|
|
|
|
int dsa_8021q_rx_switch_id(u16 vid);
|
|
|
|
|
|
|
|
|
|
int dsa_8021q_rx_source_port(u16 vid);
|
|
|
|
|
|
2021-01-29 08:59:59 +08:00
|
|
|
bool vid_is_dsa_8021q_rxvlan(u16 vid);
|
|
|
|
|
|
|
|
|
|
bool vid_is_dsa_8021q_txvlan(u16 vid);
|
|
|
|
|
|
2020-05-13 01:20:26 +08:00
|
|
|
bool vid_is_dsa_8021q(u16 vid);
|
|
|
|
|
|
net: dsa: Optional VLAN-based port separation for switches without tagging
This patch provides generic DSA code for using VLAN (802.1Q) tags for
the same purpose as a dedicated switch tag for injection/extraction.
It is based on the discussions and interest that has been so far
expressed in https://www.spinics.net/lists/netdev/msg556125.html.
Unlike all other DSA-supported tagging protocols, CONFIG_NET_DSA_TAG_8021Q
does not offer a complete solution for drivers (nor can it). Instead, it
provides generic code that driver can opt into calling:
- dsa_8021q_xmit: Inserts a VLAN header with the specified contents.
Can be called from another tagging protocol's xmit function.
Currently the LAN9303 driver is inserting headers that are simply
802.1Q with custom fields, so this is an opportunity for code reuse.
- dsa_8021q_rcv: Retrieves the TPID and TCI from a VLAN-tagged skb.
Removing the VLAN header is left as a decision for the caller to make.
- dsa_port_setup_8021q_tagging: For each user port, installs an Rx VID
and a Tx VID, for proper untagged traffic identification on ingress
and steering on egress. Also sets up the VLAN trunk on the upstream
(CPU or DSA) port. Drivers are intentionally left to call this
function explicitly, depending on the context and hardware support.
The expected switch behavior and VLAN semantics should not be violated
under any conditions. That is, after calling
dsa_port_setup_8021q_tagging, the hardware should still pass all
ingress traffic, be it tagged or untagged.
For uniformity with the other tagging protocols, a module for the
dsa_8021q_netdev_ops structure is registered, but the typical usage is
to set up another tagging protocol which selects CONFIG_NET_DSA_TAG_8021Q,
and calls the API from tag_8021q.h. Null function definitions are also
provided so that a "depends on" is not forced in the Kconfig.
This tagging protocol only works when switch ports are standalone, or
when they are added to a VLAN-unaware bridge. It will probably remain
this way for the reasons below.
When added to a bridge that has vlan_filtering 1, the bridge core will
install its own VLANs and reset the pvids through switchdev. For the
bridge core, switchdev is a write-only pipe. All VLAN-related state is
kept in the bridge core and nothing is read from DSA/switchdev or from
the driver. So the bridge core will break this port separation because
it will install the vlan_default_pvid into all switchdev ports.
Even if we could teach the bridge driver about switchdev preference of a
certain vlan_default_pvid (task difficult in itself since the current
setting is per-bridge but we would need it per-port), there would still
exist many other challenges.
Firstly, in the DSA rcv callback, a driver would have to perform an
iterative reverse lookup to find the correct switch port. That is
because the port is a bridge slave, so its Rx VID (port PVID) is subject
to user configuration. How would we ensure that the user doesn't reset
the pvid to a different value (which would make an O(1) translation
impossible), or to a non-unique value within this DSA switch tree (which
would make any translation impossible)?
Finally, not all switch ports are equal in DSA, and that makes it
difficult for the bridge to be completely aware of this anyway.
The CPU port needs to transmit tagged packets (VLAN trunk) in order for
the DSA rcv code to be able to decode source information.
But the bridge code has absolutely no idea which switch port is the CPU
port, if nothing else then just because there is no netdevice registered
by DSA for the CPU port.
Also DSA does not currently allow the user to specify that they want the
CPU port to do VLAN trunking anyway. VLANs are added to the CPU port
using the same flags as they were added on the user port.
So the VLANs installed by dsa_port_setup_8021q_tagging per driver
request should remain private from the bridge's and user's perspective,
and should not alter the VLAN semantics observed by the user.
In the current implementation a VLAN range ending at 4095 (VLAN_N_VID)
is reserved for this purpose. Each port receives a unique Rx VLAN and a
unique Tx VLAN. Separate VLANs are needed for Rx and Tx because they
serve different purposes: on Rx the switch must process traffic as
untagged and process it with a port-based VLAN, but with care not to
hinder bridging. On the other hand, the Tx VLAN is where the
reachability restrictions are imposed, since by tagging frames in the
xmit callback we are telling the switch onto which port to steer the
frame.
Some general guidance on how this support might be employed for
real-life hardware (some comments made by Florian Fainelli):
- If the hardware supports VLAN tag stacking, it should somehow back
up its private VLAN settings when the bridge tries to override them.
Then the driver could re-apply them as outer tags. Dedicating an outer
tag per bridge device would allow identical inner tag VID numbers to
co-exist, yet preserve broadcast domain isolation.
- If the switch cannot handle VLAN tag stacking, it should disable this
port separation when added as slave to a vlan_filtering bridge, in
that case having reduced functionality.
- Drivers for old switches that don't support the entire VLAN_N_VID
range will need to rework the current range selection mechanism.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-05 18:19:22 +08:00
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#endif /* _NET_DSA_8021Q_H */
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