Many tagging protocols deal with the transmit port mask being a bit
mask, and set it to BIT(dp->index). Not a big deal.
Also, some tagging protocols are written for switches which support HSR
offload (including packet duplication offload), there we see a walk
using dsa_hsr_foreach_port() to find the other port in the same switch
that's member of the HSR, and set that bit in the port mask too.
That isn't sufficiently interesting either, until you come to realize
that there isn't anything special in the second case that switches just
in the first one can't do too.
It just becomes a matter of "is it wise to do it? are sufficient people
using HSR/PRP with generic off-the-shelf switches to justify add an
extra test in the data path?" - the answer to which is probably "it
depends". It isn't _much_ worse to not have HSR offload at all, so as to
make it impractical, esp. with a rich OS like Linux. But the HSR users
are rather specialized in industrial networking.
Anyway, the change acts on the premise that we're going to have support
for this, it should be uniformly implemented for everyone, and that if
we find some sort of balance, we can keep everyone relatively happy.
So I've disabled that logic if CONFIG_HSR isn't enabled, and I've tilted
the branch predictor to say it's unlikely we're transmitting through a
port with this capability currently active. On branch miss, we're still
going to save the transmission of one packet, so there's some remaining
benefit there too. I don't _think_ we need to jump to static keys yet.
The helper returns a 32-bit zero-based unsigned number, that callers
have to transpose using FIELD_PREP(). It is not the first time we assume
DSA switches won't be larger than 32 ports - dsa_user_ports() has that
assumption baked into it too.
One last development note about why pass the "skb" argument when this
isn't used. Looking at the compiled code on arm64, which is identical
both with and without it, the answer is "why not?" - who knows what
other features dependent on the skb may be handled in the future.
Link: https://lore.kernel.org/netdev/20251126093240.2853294-4-mmyangfl@gmail.com/
Cc: "Alvin Šipraga" <alsi@bang-olufsen.dk>
Cc: Chester A. Unal" <chester.a.unal@arinc9.com>
Cc: "Clément Léger" <clement.leger@bootlin.com>
Cc: Daniel Golle <daniel@makrotopia.org>
Cc: David Yang <mmyangfl@gmail.com>
Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: George McCollister <george.mccollister@gmail.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Jonas Gorski <jonas.gorski@gmail.com>
Cc: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Sean Wang <sean.wang@mediatek.com>
Cc: UNGLinuxDriver@microchip.com
Cc: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20251127120902.292555-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Robert Hodaszi reports that locally terminated traffic towards
VLAN-unaware bridge ports is broken with ocelot-8021q. He is describing
the same symptoms as for commit 1f9fc48fd3 ("net: dsa: sja1105: fix
reception from VLAN-unaware bridges").
For context, the set merged as "VLAN fixes for Ocelot driver":
https://lore.kernel.org/netdev/20240815000707.2006121-1-vladimir.oltean@nxp.com/
was developed in a slightly different form earlier this year, in January.
Initially, the switch was unconditionally configured to set OCELOT_ES0_TAG
when using ocelot-8021q, regardless of port operating mode.
This led to the situation where VLAN-unaware bridge ports would always
push their PVID - see ocelot_vlan_unaware_pvid() - a negligible value
anyway - into RX packets. To strip this in software, we would have needed
DSA to know what private VID the switch chose for VLAN-unaware bridge
ports, and pushed into the packets. This was implemented downstream, and
a remnant of it remains in the form of a comment mentioning
ds->ops->get_private_vid(), as something which would maybe need to be
considered in the future.
However, for upstream, it was deemed inappropriate, because it would
mean introducing yet another behavior for stripping VLAN tags from
VLAN-unaware bridge ports, when one already existed (ds->untag_bridge_pvid).
The latter has been marked as obsolete along with an explanation why it
is logically broken, but still, it would have been confusing.
So, for upstream, felix_update_tag_8021q_rx_rule() was developed, which
essentially changed the state of affairs from "Felix with ocelot-8021q
delivers all packets as VLAN-tagged towards the CPU" into "Felix with
ocelot-8021q delivers all packets from VLAN-aware bridge ports towards
the CPU". This was done on the premise that in VLAN-unaware mode,
there's nothing useful in the VLAN tags, and we can avoid introducing
ds->ops->get_private_vid() in the DSA receive path if we configure the
switch to not push those VLAN tags into packets in the first place.
Unfortunately, and this is when the trainwreck started, the selftests
developed initially and posted with the series were not re-ran.
dsa_software_vlan_untag() was initially written given the assumption
that users of this feature would send _all_ traffic as VLAN-tagged.
It was only partially adapted to the new scheme, by removing
ds->ops->get_private_vid(), which also used to be necessary in
standalone ports mode.
Where the trainwreck became even worse is that I had a second opportunity
to think about this, when the dsa_software_vlan_untag() logic change
initially broke sja1105, in commit 1f9fc48fd3 ("net: dsa: sja1105: fix
reception from VLAN-unaware bridges"). I did not connect the dots that
it also breaks ocelot-8021q, for pretty much the same reason that not
all received packets will be VLAN-tagged.
To be compatible with the optimized Felix control path which runs
felix_update_tag_8021q_rx_rule() to only push VLAN tags when useful (in
VLAN-aware mode), we need to restore the old dsa_software_vlan_untag()
logic. The blamed commit introduced the assumption that
dsa_software_vlan_untag() will see only VLAN-tagged packets, assumption
which is false. What corrupts RX traffic is the fact that we call
skb_vlan_untag() on packets which are not VLAN-tagged in the first
place.
Fixes: 93e4649efa ("net: dsa: provide a software untagging function on RX for VLAN-aware bridges")
Reported-by: Robert Hodaszi <robert.hodaszi@digi.com>
Closes: https://lore.kernel.org/netdev/20241215163334.615427-1-robert.hodaszi@digi.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241216135059.1258266-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Through code analysis, I realized that the ds->untag_bridge_pvid logic
is contradictory - see the newly added FIXME above the kernel-doc for
dsa_software_untag_vlan_unaware_bridge().
Moreover, for the Felix driver, I need something very similar, but which
is actually _not_ contradictory: untag the bridge PVID on RX, but for
VLAN-aware bridges. The existing logic does it for VLAN-unaware bridges.
Since I don't want to change the functionality of drivers which were
supposedly properly tested with the ds->untag_bridge_pvid flag, I have
introduced a new one: ds->untag_vlan_aware_bridge_pvid, and I have
refactored the DSA reception code into a common path for both flags.
TODO: both flags should be unified under a single ds->software_vlan_untag,
which users of both current flags should set. This is not something that
can be carried out right away. It needs very careful examination of all
drivers which make use of this functionality, since some of them
actually get this wrong in the first place.
For example, commit 9130c2d30c ("net: dsa: microchip: ksz8795: Use
software untagging on CPU port") uses this in a driver which has
ds->configure_vlan_while_not_filtering = true. The latter mechanism has
been known for many years to be broken by design:
https://lore.kernel.org/netdev/CABumfLzJmXDN_W-8Z=p9KyKUVi_HhS7o_poBkeKHS2BkAiyYpw@mail.gmail.com/
and we have the situation of 2 bugs canceling each other. There is no
private VLAN, and the port follows the PVID of the VLAN-unaware bridge.
So, it's kinda ok for that driver to use the ds->untag_bridge_pvid
mechanism, in a broken way.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Once commit 6d1ccff627 ("net: reset mac header in dev_start_xmit()")
will be reverted, it will no longer be true that skb->data points at
skb_mac_header(skb) - since the skb->mac_header will not be set - so
stop saying that, and just say that it points to the MAC header.
I've reviewed vlan_insert_tag() and it does not *actually* depend on
skb_mac_header(), so reword that to avoid the confusion.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It would be nice if tagging protocol drivers could include just the
header they need, since they are (mostly) data path and isolated from
most of the other DSA core code does.
Create a tag.c and a tag.h file which are meant to support tagging
protocol drivers.
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>
