Stop room is a space that may be taken by WQEs in the SQ during a packet
transmit. It is used to check if next packet has enough room in the SQ.
Stop room guarantees this packet can be served and if not, the queue is
stopped, so no more packets are passed to the driver until it's ready.

Currently, stop_room size is calculated and validated upon tx queues
allocation. This makes it impossible to know if user provided valid
input for certain parameters when interface is down.

Instead, store stop_room in mlx5e_sq_param and create
mlx5e_validate_params(), to validate its fields upon user input even
when the interface is down.
Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Track buddy's used ICM memory, and free it if all
of the buddy's memory bacame unused.
Do this only for STEs.
MODIFY_ACTION buddies are much smaller, so in case there
is a large amount of modify_header actions, which result
in large amount of MODIFY_ACTION buddies, doing this
cleanup during sync will result in performance hit while
not freeing significant amount of memory.
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Track the pool's hot ICM memory when freeing/allocating
chunk, so that when checking if the sync is required, just
check if the pool hot memory has reached the sync threshold.
Signed-off-by: Hamdan Igbaria <hamdani@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

When freeing chunks, we want to sync the steering
so that all the "hot" memory will be written to ICM
and all the chunks that are in the hot_list will be
actually destroyed.
When allocating from the pool, we don't have a need
to sync the steering, as we're not freeing anything,
and sync might just hurt the performance in terms of
flow-per-second offloaded.
Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Till now in order to manage the ICM memory we used bucket
mechanism, which kept a bucket per specified size (sizes were
between 1 block to 2^21 blocks).

Now changing that with buddy-system mechanism, which gives us much
more flexible way to manage the ICM memory.
Its biggest advantage over the bucket is by using the same ICM memory
area for all the sizes of blocks, which reduces the memory consumption.
Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Add implementation of SW Steering variation of buddy allocator.

The buddy system for ICM memory uses 2 main data structures:
- Bitmap per order, that keeps the current state of allocated
  blocks for this order
- Indicator for the number of available blocks per each order
Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Remove flex parser from the matcher function names since
the matcher should not be aware of such HW specific details.
Signed-off-by: Alex Vesker <valex@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

We will support multiple STE versions.
The existing naming is not suitable for newer versions.
Removed the HW specific details and renamed with a more
general names.
Signed-off-by: Alex Vesker <valex@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Struct mlx5dr_action doesn't use this member
Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Aleksandr Nogikh says:

====================
net, mac80211, kernel: enable KCOV remote coverage collection for 802.11 frame handling

This patch series enables remote KCOV coverage collection during
802.11 frames processing. These changes make it possible to perform
coverage-guided fuzzing in search of remotely triggerable bugs.

Normally, KCOV collects coverage information for the code that is
executed inside the system call context. It is easy to identify where
that coverage should go and whether it should be collected at all by
looking at the current process. If KCOV was enabled on that process,
coverage will be stored in a buffer specific to that process.
Howerever, it is not always enough as handling can happen elsewhere
(e.g. in separate kernel threads).

When it is impossible to infer KCOV-related info just by looking at
the currently running process, one needs to manually pass some
information to the code that should be instrumented. The information
takes the form of 64 bit integers (KCOV remote handles). Zero is the
special value that corresponds to an empty handle. More details on
KCOV and remote coverage collection can be found in
Documentation/dev-tools/kcov.rst.

The series consists of three commits.
1. Apply a minor fix to kcov_common_handle() so that it returns a
valid handle (zero) when called in an interrupt context.
2. Take the remote handle from KCOV and attach it to newly allocated
SKBs as an skb extension. If the allocation happens inside a system
call context, the SKB will be tied to the process that issued the
syscall (if that process is interested in remote coverage collection).
3. Annotate the code that processes incoming 802.11 frames with
kcov_remote_start()/kcov_remote_stop().

v5:
* Collecting remote coverate at ieee80211_rx_list() instead of
  ieee80211_rx()

v4:
https://lkml.kernel.org/r/20201028182018.1780842-1-aleksandrnogikh@gmail.com
* CONFIG_SKB_EXTENSIONS is now automatically selected by CONFIG_KCOV.
* Elaborated on a minor optimization in skb_set_kcov_handle().

v3:
https://lkml.kernel.org/r/20201026150851.528148-1-aleksandrnogikh@gmail.com
* kcov_handle is now stored in skb extensions instead of sk_buff
  itself.
* Updated the cover letter.

v2:
https://lkml.kernel.org/r/20201009170202.103512-1-a.nogikh@gmail.com
* Moved KCOV annotations from ieee80211_tasklet_handler to
  ieee80211_rx.
* Updated kcov_common_handle() to return 0 if it is called in
  interrupt context.
* Updated the cover letter.

v1:
https://lkml.kernel.org/r/20201007101726.3149375-1-a.nogikh@gmail.com
====================

Link: https://lore.kernel.org/r/20201029173620.2121359-1-aleksandrnogikh@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add KCOV remote annotations to ieee80211_iface_work() and
ieee80211_rx_list(). This will enable coverage-guided fuzzing of
mac80211 code that processes incoming 802.11 frames.
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Remote KCOV coverage collection enables coverage-guided fuzzing of the
code that is not reachable during normal system call execution. It is
especially helpful for fuzzing networking subsystems, where it is
common to perform packet handling in separate work queues even for the
packets that originated directly from the user space.

Enable coverage-guided frame injection by adding kcov remote handle to
skb extensions. Default initialization in __alloc_skb and
__build_skb_around ensures that no socket buffer that was generated
during a system call will be missed.

Code that is of interest and that performs packet processing should be
annotated with kcov_remote_start()/kcov_remote_stop().

An alternative approach is to determine kcov_handle solely on the
basis of the device/interface that received the specific socket
buffer. However, in this case it would be impossible to distinguish
between packets that originated during normal background network
processes or were intentionally injected from the user space.
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

kcov_common_handle is a method that is used to obtain a "default" KCOV
remote handle of the current process. The handle can later be passed
to kcov_remote_start in order to collect coverage for the processing
that is initiated by one process, but done in another. For details see
Documentation/dev-tools/kcov.rst and comments in kernel/kcov.c.

Presently, if kcov_common_handle is called in an IRQ context, it will
return a handle for the interrupted process. This may lead to
unreliable and incorrect coverage collection.

Adjust the behavior of kcov_common_handle in the following way. If it
is called in a task context, return the common handle for the
currently running task. Otherwise, return 0.
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201031153047.2147341-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20201101140528.2279424-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201101140720.2280013-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20201101153647.2292322-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201101155601.2294374-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201101155822.2294856-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Vladimir Oltean says:

====================
Generic TX reallocation for DSA

Christian has reported buggy usage of skb_put() in tag_ksz.c, which is
only triggerable in real life using his not-yet-published patches for
IEEE 1588 timestamping on Micrel KSZ switches.

The concrete problem there is that the driver can end up calling
skb_put() and exceed the end of the skb data area, because even though
it had reallocated the frame once before, it hadn't reallocated it large
enough. Christian explained it in more detail here:

https://lore.kernel.org/netdev/20201014161719.30289-1-ceggers@arri.de/
https://lore.kernel.org/netdev/20201016200226.23994-1-ceggers@arri.de/

But actually there's a bigger problem, which is that some taggers which
get more rarely tested tend to do some shenanigans which are uncaught
for the longest time, and in the meanwhile, their code gets copy-pasted
into other taggers, creating a mess. For example, the tail tagging
driver for Marvell 88E6060 currently reallocates _every_single_frame_ on
TX. Is that an obvious indication that nobody is using it? Sure. Is it a
good model to follow when developing a new tail tagging driver? No.

DSA has all the information it needs in order to simplify the job of a
tagger on TX. It knows whether it's a normal or a tail tagger, and what
is the protocol overhead it incurs. So this series performs the
reallocation centrally.

Changes in v3:
- Use dev_kfree_skb_any due to potential hardirq context in xmit path.

Changes in v2:
- Dropped the tx_realloc counters for now, since the patch was pretty
  controversial and I lack the time at the moment to introduce new UAPI
  for that.
- Do padding for tail taggers irrespective of whether they need to
  reallocate the skb or not.
====================

Link: https://lore.kernel.org/r/20201101191620.589272-1-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Cc: Per Forlin <per.forlin@axis.com>
Cc: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

This one is interesting, the DSA tag is 8 bytes on RX and 4 bytes on TX.
Because DSA is unaware of asymmetrical tag lengths, the overhead/needed
headroom is declared as 8 bytes and therefore 4 bytes larger than it
needs to be. If this becomes a problem, and the GSWIP driver can't be
converted to a uniform header length, we might need to make DSA aware of
separate RX/TX overhead values.

Cc: Hauke Mehrtens <hauke@hauke-m.de>
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Similar to the EtherType DSA tagger, the old Marvell tagger can
transform an 802.1Q header if present into a DSA tag, so there is no
headroom required in that case. But we are ensuring that it exists,
regardless (practically speaking, the headroom must be 4 bytes larger
than it needs to be).
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Cc: Florian Fainelli <f.fainelli@gmail.com>
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Note that the VLAN code path needs a smaller extra headroom than the
regular EtherType DSA path. That isn't a problem, because this tagger
declares the larger tag length (8 bytes vs 4) as the protocol overhead,
so we are covered in both cases.

Cc: Andrew Lunn <andrew@lunn.ch>
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Sean Wang <sean.wang@mediatek.com>
Cc: John Crispin <john@phrozen.org>
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.
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>

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

Cc: John Crispin <john@phrozen.org>
Cc: Alexander Lobakin <alobakin@pm.me>
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>

The caller (dsa_slave_xmit) guarantees that the frame length is at least
ETH_ZLEN and that enough memory for tail tagging is available.
Signed-off-by: Christian Eggers <ceggers@arri.de>
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>

The caller (dsa_slave_xmit) guarantees that the frame length is at least
ETH_ZLEN and that enough memory for tail tagging is available.
Signed-off-by: Christian Eggers <ceggers@arri.de>
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>

At the moment, taggers are left with the task of ensuring that the skb
headers are writable (which they aren't, if the frames were cloned for
TX timestamping, for flooding by the bridge, etc), and that there is
enough space in the skb data area for the DSA tag to be pushed.

Moreover, the life of tail taggers is even harder, because they need to
ensure that short frames have enough padding, a problem that normal
taggers don't have.

The principle of the DSA framework is that everything except for the
most intimate hardware specifics (like in this case, the actual packing
of the DSA tag bits) should be done inside the core, to avoid having
code paths that are very rarely tested.

So provide a TX reallocation procedure that should cover the known needs
of DSA today.

Note that this patch also gives the network stack a good hint about the
headroom/tailroom it's going to need. Up till now it wasn't doing that.
So the reallocation procedure should really be there only for the
exceptional cases, and for cloned packets which need to be unshared.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Christian Eggers <ceggers@arri.de> # For tail taggers only
Tested-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Fix smatch warning:

net/openvswitch/meter.c:427 ovs_meter_cmd_set() warn: passing zero to 'PTR_ERR'

dp_meter_create() never returns NULL, use IS_ERR
instead of IS_ERR_OR_NULL to fix this.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Link: https://lore.kernel.org/r/20201031060153.39912-1-yuehaibing@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Remove duplicated include.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20201031024940.29716-1-yuehaibing@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Remove duplicated include.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20201031024744.39020-1-yuehaibing@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

During TCP fast recovery, the congestion control in charge is by
default the Proportional Rate Reduction (PRR) unless the congestion
control module specified otherwise (e.g. BBR).

Previously when tcp_packets_in_flight() is below snd_ssthresh PRR
would slow start upon receiving an ACK that
   1) cumulatively acknowledges retransmitted data
   and
   2) does not detect further lost retransmission

Such conditions indicate the repair is in good steady progress
after the first round trip of recovery. Otherwise PRR adopts the
packet conservation principle to send only the amount that was
newly delivered (indicated by this ACK).

This patch generalizes the previous design principle to include
also the newly sent data beside retransmission: as long as
the delivery is making good progress, both retransmission and
new data should be accounted to make PRR more cautious in slow
starting.
Suggested-by: Matt Mathis <mattmathis@google.com>
Suggested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201031013412.1973112-1-ycheng@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Vladimir Oltean says:

====================
VLAN improvements for Ocelot switch

The main reason why I started this work is that deleting the bridge mdb
entries fails when the bridge is deleted, as described here:
https://lore.kernel.org/netdev/20201015173355.564934-1-vladimir.oltean@nxp.com/

In short, that happens because the bridge mdb entries are added with a
vid of 1, but deletion is attempted with a vid of 0. So the deletion
code fails to find the mdb entries.

The solution is to make ocelot use a pvid of 0 when it is under a bridge
with vlan_filtering 0. When vlan_filtering is 1, the pvid of the bridge
is what is programmed into the hardware.

The patch series also uncovers more bugs and does some more cleanup, but
the above is the main idea behind it.
====================

Link: https://lore.kernel.org/r/20201031102916.667619-1-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

After the good discussion with Florian from here:
https://lore.kernel.org/netdev/20200911000337.htwr366ng3nc3a7d@skbuf/

I realized that the VLAN settings on the NPI port (the hardware "CPU port",
in DSA parlance) don't actually make any difference, because that port
is hardcoded in hardware to use what mv88e6xxx would call "unmodified"
egress policy for VLANs.

So earlier patch 183be6f9 ("net: dsa: felix: send VLANs on CPU port
as egress-tagged") was incorrect in the sense that it didn't actually
make the VLANs be sent on the NPI port as egress-tagged. It only made
ocelot_port_set_native_vlan shut up.

Now that we have moved the check from ocelot_port_set_native_vlan to
ocelot_vlan_prepare, we can simply shunt ocelot_vlan_prepare from DSA,
and avoid calling it. This is the correct way to deal with things,
because the NPI port configuration is DSA-specific, so the ocelot switch
library should not have the check for multiple native VLANs refined in
any way, it is correct the way it is.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Put the preparation phase of switchdev VLAN objects to some good use,
and move the check we already had, for preventing the existence of more
than one egress-untagged VLAN per port, to the preparation phase of the
addition.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Currently, the ocelot_port_set_native_vlan() function starts dropping
untagged and prio-tagged traffic when the native VLAN is removed?

What is the native VLAN? It is the only egress-untagged VLAN that ocelot
supports on a port. If the port is a trunk with 100 VLANs, one of those
VLANs can be transmitted as egress-untagged, and that's the native VLAN.

Is it wrong to drop untagged and prio-tagged traffic if there's no
native VLAN? Yes and no.

In this case, which is more typical, it's ok to apply that drop
configuration:
$ bridge vlan add dev swp0 vid 1 pvid untagged <- this is the native VLAN
$ bridge vlan add dev swp0 vid 100
$ bridge vlan add dev swp0 vid 101
$ bridge vlan del dev swp0 vid 1 <- delete the native VLAN
But only because the pvid and the native VLAN have the same ID.

In this case, it isn't:
$ bridge vlan add dev swp0 vid 1 pvid
$ bridge vlan add dev swp0 vid 100 untagged <- this is the native VLAN
$ bridge vlan del dev swp0 vid 101
$ bridge vlan del dev swp0 vid 100 <- delete the native VLAN

It's wrong, because the switch will drop untagged and prio-tagged
traffic now, despite having a valid pvid of 1.

The confusion seems to stem from the fact that the native VLAN is an
egress setting, while the PVID is an ingress setting. It would be
correct to drop untagged and prio-tagged traffic only if there was no
pvid on the port. So let's do just that.

Background:
https://lore.kernel.org/netdev/CA+h21hrRMrLH-RjBGhEJSTZd6_QPRSd3RkVRQF-wNKkrgKcRSA@mail.gmail.com/#tSigned-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>