Jakub Kicinski 2cb7b4890d devlink: expose instance locking and add locked port registering
It should be familiar and beneficial to expose devlink instance
lock to the drivers. This way drivers can block devlink from
calling them during critical sections without breakneck locking.

Add port helpers, port splitting callbacks will be the first
target.

Use 'devl_' prefix for "explicitly locked" API. Initial RFC used
'__devlink' but that's too much typing.

devl_lock_is_held() is not defined without lockdep, which is
the same behavior as lockdep_is_held() itself.

Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-03-16 12:56:31 -07:00

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Linux Devlink Documentation
===========================
devlink is an API to expose device information and resources not directly
related to any device class, such as chip-wide/switch-ASIC-wide configuration.
Locking
-------
Driver facing APIs are currently transitioning to allow more explicit
locking. Drivers can use the existing ``devlink_*`` set of APIs, or
new APIs prefixed by ``devl_*``. The older APIs handle all the locking
in devlink core, but don't allow registration of most sub-objects once
the main devlink object is itself registered. The newer ``devl_*`` APIs assume
the devlink instance lock is already held. Drivers can take the instance
lock by calling ``devl_lock()``. It is also held in most of the callbacks.
Eventually all callbacks will be invoked under the devlink instance lock,
refer to the use of the ``DEVLINK_NL_FLAG_NO_LOCK`` flag in devlink core
to find out which callbacks are not converted, yet.
Drivers are encouraged to use the devlink instance lock for their own needs.
Interface documentation
-----------------------
The following pages describe various interfaces available through devlink in
general.
.. toctree::
:maxdepth: 1
devlink-dpipe
devlink-health
devlink-info
devlink-flash
devlink-params
devlink-port
devlink-region
devlink-resource
devlink-reload
devlink-trap
Driver-specific documentation
-----------------------------
Each driver that implements ``devlink`` is expected to document what
parameters, info versions, and other features it supports.
.. toctree::
:maxdepth: 1
bnxt
hns3
ionic
ice
mlx4
mlx5
mlxsw
mv88e6xxx
netdevsim
nfp
qed
ti-cpsw-switch
am65-nuss-cpsw-switch
prestera
iosm
octeontx2