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Vladimir Oltean a3b16198d3 selftests: forwarding: add a pvid_change test to bridge_vlan_unaware 
Historically, DSA drivers have seen problems with the model in which
bridge VLANs work, particularly with them being offloaded to switchdev
asynchronously relative to when they become active (vlan_filtering=1).

This switchdev API peculiarity was papered over by commit 2ea7a679ca
("net: dsa: Don't add vlans when vlan filtering is disabled"), which
introduced other problems, fixed by commit 54a0ed0df4 ("net: dsa:
provide an option for drivers to always receive bridge VLANs") through
an opt-in ds->configure_vlan_while_not_filtering bool (which later
became an opt-out).

The point is that some DSA drivers still skip VLAN configuration while
VLAN-unaware, and there is a desire to get rid of that behavior.

It's hard to deduce from the wording "at least one corner case" what
Andrew saw, but my best guess is that there is a discrepancy of meaning
between bridge pvid and hardware port pvid which caused breakage.

On one side, the Linux bridge with vlan_filtering=0 is completely
VLAN-unaware, and will accept and process a packet the same way
irrespective of the VLAN groups on the ports or the bridge itself
(there may not even be a pvid, and this makes no difference).

On the other hand, DSA switches still do VLAN processing internally,
even with vlan_filtering disabled, but they are expected to classify all
packets to the port pvid. That pvid shouldn't be confused with the
bridge pvid, and there lies the problem.

When a switch port is under a VLAN-unaware bridge, the hardware pvid
must be explicitly managed by the driver to classify all received
packets to it, regardless of bridge VLAN groups. When under a VLAN-aware
bridge, the hardware pvid must be synchronized to the bridge port pvid.
To do this correctly, the pattern is unfortunately a bit complicated,
and involves hooking the pvid change logic into quite a few places
(the ones that change the input variables which determine the value to
use as hardware pvid for a port). See mv88e6xxx_port_commit_pvid(),
sja1105_commit_pvid(), ocelot_port_set_pvid() etc.

The point is that not all drivers used to do that, especially in older
kernels. If a driver is to blindly program a bridge pvid VLAN received
from switchdev while it's VLAN-unaware, this might in turn change the
hardware pvid used by a VLAN-unaware bridge port, which might result in
packet loss depending which other ports have that pvid too (in that same
note, it might also go unnoticed).

To capture that condition, it is sufficient to take a VLAN-unaware
bridge and change the [VLAN-aware] bridge pvid on a single port, to a
VID that isn't present on any other port. This shouldn't have absolutely
any effect on packet classification or forwarding. However, broken
drivers will take the bait, and change their PVID to 3, causing packet
loss.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20241210233541.1401837-1-vladimir.oltean@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-12-12 12:16:39 +01:00
arch LoongArch fixes for v6.13-rc2 2024-12-04 10:31:37 -08:00
block block-6.13-20242901 2024-11-30 15:47:29 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
Documentation tcp: Add sysctl to configure TIME-WAIT reuse delay 2024-12-11 20:17:33 -08:00
drivers ionic: add support for QSFP_PLUS_CMIS 2024-12-12 12:06:33 +01:00
fs for-6.13-rc1-tag 2024-12-03 11:02:17 -08:00
include net: dsa: provide implementation of .support_eee() 2024-12-11 20:29:38 -08:00
init - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
io_uring io_uring-6.13-20242901 2024-11-30 15:43:02 -08:00
ipc - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
kernel bpf, xdp: constify some bpf_prog * function arguments 2024-12-05 18:41:06 -08:00
lib lib: packing: add pack_fields() and unpack_fields() 2024-12-11 20:13:00 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
net net: dsa: require .support_eee() method to be implemented 2024-12-11 20:29:39 -08:00
rust block-6.13-20242901 2024-11-30 15:47:29 -08:00
samples module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
scripts lib: packing: add pack_fields() and unpack_fields() 2024-12-11 20:13:00 -08:00
security Including fixes from can and netfilter. 2024-12-05 10:25:06 -08:00
sound module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
tools selftests: forwarding: add a pvid_change test to bridge_vlan_unaware 2024-12-12 12:16:39 +01:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt VFIO updates for v6.13 2024-11-27 12:57:03 -08:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: enable Clippy's check-private-items 2024-10-07 21:39:57 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes
.gitignore Kbuild updates for v6.13 2024-11-30 13:41:50 -08:00
.mailmap media updates for v6.13-rc1 2024-11-20 14:01:15 -08:00
.rustfmt.toml
COPYING
CREDITS cgroup: Changes for v6.13 2024-11-20 09:54:49 -08:00
Kbuild
Kconfig
MAINTAINERS lib: packing: add pack_fields() and unpack_fields() 2024-12-11 20:13:00 -08:00
Makefile lib: packing: add pack_fields() and unpack_fields() 2024-12-11 20:13:00 -08:00
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README 

Linux kernel
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There are several guides for kernel developers and users. These guides can
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.