Merge branch 'devlink-and-mlx5-support-cross-function-rate-scheduling'

Tariq Toukan says:

====================
devlink and mlx5: Support cross-function rate scheduling

This series by Cosmin adds support for cross-function rate scheduling in
devlink and mlx5.
See detailed explanation by Cosmin below [0].

[0]
devlink objects support rate management for TX scheduling, which
involves maintaining a tree of rate nodes that corresponds to TX
schedulers in hardware. 'man devlink-rate' has the full details.

The tree of rate nodes is maintained per devlink object, protected by
the devlink lock.

There exists hardware capable of instantiating TX scheduling trees
spanning multiple functions of the same physical device (and thus
devlink objects) and therefore the current API and locking scheme is
insufficient.

This patch series changes the devlink rate implementation and API to
allow supporting such hardware and managing TX scheduling trees across
multiple functions of a physical device.

Modeling this requires having devlink rate nodes with parents in other
devlink objects. A naive approach that relies on the current
one-lock-per-devlink model is impossible, as it would require in some
cases acquiring multiple devlink locks in the correct order.

The solution proposed in this patch series makes use of the recently
introduced shared devlink instance [1] to manage rate hierarchy changes
across multiple functions.

V1 of this patch series was sent a long time ago [2], using a different
approach of storing rates in a shared rate domain with special locking
rules. This new approach uses standard devlink instances and nesting.

The first part of the series adds support to devlink rates for
maintaining the rate tree across multiple functions.

The second part changes the mlx5 implementation to make use of this (and
cleans up remnants of the previous approach, involving rate domains).

The neat part about using the shared devlink object is that it works for
SFs as well, which are already nested in their parent PF instances. So
with this series, complex scheduling trees spanning multiple SFs across
multiple PFs of the same NIC can now be supported.
====================

Link: https://patch.msgid.link/20260701073254.754518-1-tariqt@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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