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>
Use more inclusive terms throughout the DSA subsystem by moving away
from "master" which is replaced by "conduit" and "slave" which is
replaced by "user". No functional changes.
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20231023181729.1191071-2-florian.fainelli@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We collect the software statistics counters for RX bytes (reported to
/proc/net/dev and to ethtool -S $dev | grep 'rx_bytes: ") at a time when
skb->len has already been adjusted by the eth_type_trans() ->
skb_pull_inline(skb, ETH_HLEN) call to exclude the L2 header.
This means that when connecting 2 DSA interfaces back to back and
sending 1 packet with length 100, the sending interface will report
tx_bytes as incrementing by 100, and the receiving interface will report
rx_bytes as incrementing by 86.
Since accounting for that in scripts is quirky and is something that
would be DSA-specific behavior (requiring users to know that they are
running on a DSA interface in the first place), the proposal is that we
treat it as a bug and fix it.
This design bug has always existed in DSA, according to my analysis:
commit 91da11f870 ("net: Distributed Switch Architecture protocol
support") also updates skb->dev->stats.rx_bytes += skb->len after the
eth_type_trans() call. Technically, prior to Florian's commit
a86d8becc3 ("net: dsa: Factor bottom tag receive functions"), each and
every vendor-specific tagging protocol driver open-coded the same bug,
until the buggy code was consolidated into something resembling what can
be seen now. So each and every driver should have its own Fixes: tag,
because of their different histories until the convergence point.
I'm not going to do that, for the sake of simplicity, but just blame the
oldest appearance of buggy code.
There are 2 ways to fix the problem. One is the obvious way, and the
other is how I ended up doing it. Obvious would have been to move
dev_sw_netstats_rx_add() one line above eth_type_trans(), and below
skb_push(skb, ETH_HLEN). But DSA processing is not as simple as that.
We count the bytes after removing everything DSA-related from the
packet, to emulate what the packet's length was, on the wire, when the
user port received it.
When eth_type_trans() executes, dsa_untag_bridge_pvid() has not run yet,
so in case the switch driver requests this behavior - commit
412a1526d0 ("net: dsa: untag the bridge pvid from rx skbs") has the
details - the obvious variant of the fix wouldn't have worked, because
the positioning there would have also counted the not-yet-stripped VLAN
header length, something which is absent from the packet as seen on the
wire (there it may be untagged, whereas software will see it as
PVID-tagged).
Fixes: f613ed665b ("net: dsa: Add support for 64-bit statistics")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ptp_classify_raw() is not exactly cheap, since it invokes a BPF program
for every skb in the receive path. For switches which do not provide
ds->ops->port_rxtstamp(), running ptp_classify_raw() provides precisely
nothing, so check for the presence of the function pointer first, since
that is much cheaper.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20221209175840.390707-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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>
