This reverts commit 7bd80ed89d72285515db673803b021469ba71ee8.

I should not have merged it to begin with due to pending review and
changes to be addressed.

Link: https://patch.msgid.link/c6f3af12df9b7998920a02027fc8893ce82afc4c.1759239721.git.pabeni@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Introduce a new document, flow_control.rst, to provide a comprehensive
guide on Ethernet Flow Control in Linux. The guide explains how flow
control works, how autonegotiation resolves pause capabilities, and how
to configure it using ethtool and Netlink.

In parallel, document the pause and pause-stat attributes in the
ethtool.yaml netlink spec. This enables the ynl tool to generate
kernel-doc comments for the corresponding enums in the UAPI header,
making the C interface self-documenting.

Finally, replace the legacy flow control section in phy.rst with a
reference to the new document and add pointers in the relevant C source
files.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20250924120241.724850-1-o.rempel@pengutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

IEEE 802.3ck-2022 defines counters for FEC bins and 802.3df-2024
clarifies it a bit further. Implement reporting interface through as
addition to FEC stats available in ethtool. Drivers can leave bin
counter uninitialized if per-lane values are provided. In this case the
core will recalculate summ for the bin.

Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Link: https://patch.msgid.link/20250924124037.1508846-2-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Implement removing additional RSS contexts via Netlink.
Technically it'd be possible to shoehorn the delete operation
into ethnl_request_ops-compatible handler. The code ends
up longer than open coded version, and I think we'll need
a custom way of sending notifications at some stage (if we
allow tying the context lifetime to the netlink socket, in
the future).

Link: https://patch.msgid.link/20250717234343.2328602-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Support creating contexts via Netlink. Setting flow hashing
fields on the new context is not supported at this stage,
it can be added later.

An empty indirection table is not supported. This is a carry
over from the IOCTL interface where empty indirection table
meant delete. We can repurpose empty indirection table in
Netlink but for now to avoid confusion reject it using the
policy.

Support letting user choose the ID for the new context. This was
not possible in IOCTL since the context ID field for the create
action had to be set to the ETH_RXFH_CONTEXT_ALLOC magic value.

Link: https://patch.msgid.link/20250717234343.2328602-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add initial support for RSS_SET, for now only operations on
the indirection table are supported.

Unlike the ioctl don't check if at least one parameter is
being changed. This is how other ethtool-nl ops behave,
so pick the ethtool-nl consistency vs copying ioctl behavior.

There are two special cases here:
 1) resetting the table to defaults;
 2) support for tables of different size.

For (1) I use an empty Netlink attribute (array of size 0).

(2) may require some background. AFAICT a lot of modern devices
allow allocating RSS tables of different sizes. mlx5 can upsize
its tables, bnxt has some "table size calculation", and Intel
folks asked about RSS table sizing in context of resource allocation
in the past. The ethtool IOCTL API has a concept of table size,
but right now the user is expected to provide a table exactly
the size the device requests. Some drivers may change the table
size at runtime (in response to queue count changes) but the
user is not in control of this. What's not great is that all
RSS contexts share the same table size. For example a device
with 128 queues enabled, 16 RSS contexts 8 queues in each will
likely have 256 entry tables for each of the 16 contexts,
while 32 would be more than enough given each context only has
8 queues. To address this the Netlink API should avoid enforcing
table size at the uAPI level, and should allow the user to express
the min table size they expect.

To fully solve (2) we will need more driver plumbing but
at the uAPI level this patch allows the user to specify
a table size smaller than what the device advertises. The device
table size must be a multiple of the user requested table size.
We then replicate the user-provided table to fill the full device
size table. This addresses the "allow the user to express the min
table size" objective, while not enforcing any fixed size.
From Netlink perspective .get_rxfh_indir_size() is now de facto
the "max" table size supported by the device.

We may choose to support table replication in ethtool, too,
when we actually plumb this thru the device APIs.

Initially I was considering moving full pattern generation
to the kernel (which queues to use, at which frequency and
what min sequence length). I don't think this complexity
would buy us much and most if not all devices have pow-2
table sizes, which simplifies the replication a lot.

Reviewed-by: Gal Pressman <gal@nvidia.com>
Link: https://patch.msgid.link/20250716000331.1378807-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Implement ETHTOOL_GRXFH over Netlink. The number of flow types is
reasonable (around 20) so report all of them at once for simplicity.

Do not maintain the flow ID mapping with ioctl at the uAPI level.
This gives us a chance to clean up the confusion that come from
RxNFC vs RxFH (flow direction vs hashing) in the ioctl.
Try to align with the names used in ethtool CLI, they seem to have
stood the test of time just fine. One annoyance is that we still
call L4 ports the weird names, but I guess they also apply to IPSec
(where they cover the SPI) so it is what it is.

 $ ynl --family ethtool --dump rss-get
 {
    "header": {
	"dev-index": 1,
	"dev-name": "enp1s0"
    },
    "hfunc": 1,
    "hkey": b"...",
    "indir": [0, 1, ...],
    "flow-hash": {
        "ether": {"l2da"},
	"ah-esp4": {"ip-src", "ip-dst"},
        "ah-esp6": {"ip-src", "ip-dst"},
        "ah4": {"ip-src", "ip-dst"},
        "ah6": {"ip-src", "ip-dst"},
        "esp4": {"ip-src", "ip-dst"},
        "esp6": {"ip-src", "ip-dst"},
        "ip4": {"ip-src", "ip-dst"},
        "ip6": {"ip-src", "ip-dst"},
        "sctp4": {"ip-src", "ip-dst"},
        "sctp6": {"ip-src", "ip-dst"},
        "udp4": {"ip-src", "ip-dst"},
        "udp6": {"ip-src", "ip-dst"}
        "tcp4": {"l4-b-0-1", "l4-b-2-3", "ip-src", "ip-dst"},
        "tcp6": {"l4-b-0-1", "l4-b-2-3", "ip-src", "ip-dst"},
    },
 }

Link: https://patch.msgid.link/20250708220640.2738464-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In preparation for RSS_SET handling in ethnl introduce Netlink
notifications for RSS. Only cover modifications, not creation
and not removal of a context, because the latter may deserve
a different notification type. We should cross that bridge
when we add the support for context add / remove via Netlink.

Link: https://patch.msgid.link/20250623231720.3124717-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the multicast group's name to the YAML spec.
Without it YNL doesn't know how to subscribe to notifications.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250623231720.3124717-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Cross-merge networking fixes after downstream PR (net-6.16-rc3).

No conflicts or adjacent changes.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>