netdev - [PATCH net-next RFC v4 15/15] devlink: Add Documentation/networking/devlink/devlink-reload.rst

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Message-Id: <1600063682-17313-16-git-send-email-moshe@mellanox.com>
Date:   Mon, 14 Sep 2020 09:08:02 +0300
From:   Moshe Shemesh <moshe@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jiri Pirko <jiri@...lanox.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Moshe Shemesh <moshe@...lanox.com>
Subject: [PATCH net-next RFC v4 15/15] devlink: Add Documentation/networking/devlink/devlink-reload.rst

Add devlink reload rst documentation file.
Update index file to include it.

Signed-off-by: Moshe Shemesh <moshe@...lanox.com>
---
v3 -> v4:
- Remove reload action fw_activate_no_reset
- Add reload actions limit levels and document the no_reset limit level
  constrains
v2 -> v3:
- Devlink reload returns the actions done
- Replace fw_live_patch action by fw_activate_no_reset
- Explain fw_activate meaning
v1 -> v2:
- Instead of reload levels driver,fw_reset,fw_live_patch have reload
  actions driver_reinit,fw_activate,fw_live_patch
---
 .../networking/devlink/devlink-reload.rst     | 80 +++++++++++++++++++
 Documentation/networking/devlink/index.rst    |  1 +
 2 files changed, 81 insertions(+)
 create mode 100644 Documentation/networking/devlink/devlink-reload.rst

diff --git a/Documentation/networking/devlink/devlink-reload.rst b/Documentation/networking/devlink/devlink-reload.rst
new file mode 100644
index 000000000000..6ac9dddd2208
--- /dev/null
+++ b/Documentation/networking/devlink/devlink-reload.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+Devlink Reload
+==============
+
+``devlink-reload`` provides mechanism to either reload driver entities,
+applying ``devlink-params`` and ``devlink-resources`` new values or firmware
+activation depends on reload action selected.
+
+Reload actions
+==============
+
+User may select a reload action.
+By default ``driver_reinit`` action is selected.
+
+.. list-table:: Possible reload actions
+   :widths: 5 90
+
+   * - Name
+     - Description
+   * - ``driver-reinit``
+     - Devlink driver entities re-initialization, including applying
+       new values to devlink entities which are used during driver
+       load such as ``devlink-params`` in configuration mode
+       ``driverinit`` or ``devlink-resources``
+   * - ``fw_activate``
+     - Firmware activate. Activates new firmware if such image is stored and
+       pending activation. This action involves firmware reset, if no new image
+       pending this action will reload current firmware image.
+
+Note that when required to do firmware activation some drivers may need
+to reload the driver. On the other hand some drivers may need to reset
+the firmware to reinitialize the driver entities. Therefore, the devlink
+reload command returns the actions which were actually performed.
+
+Reload action limit levels
+==========================
+
+By default reload actions are not limited and Driver implementation may
+include reset or downtime as needed to perform the actions.
+
+However, some drivers support action limit levels, which limits the action
+implementation to specific constrains.
+
+.. list-table:: Possible reload action limit levels
+   :widths: 5 90
+
+   * - Name
+     - Description
+   * - ``no_reset``
+     - No reset allowed, no down time allowed, no link flap and no
+       configuration is lost.
+
+Change namespace
+================
+
+All devlink instances are created in init_net and stay there for a
+lifetime. Allow user to be able to move devlink instances into
+namespaces during devlink reload operation. That ensures proper
+re-instantiation of driver objects, including netdevices.
+
+example usage
+-------------
+
+.. code:: shell
+
+    $ devlink dev reload help
+    $ devlink dev reload DEV [ netns { PID | NAME | ID } ] [ action { driver_reinit | fw_activate } ] [limit_level no_reset]
+
+    # Run reload command for devlink driver entities re-initialization:
+    $ devlink dev reload pci/0000:82:00.0 action driver_reinit
+    reload_actions_performed:
+      driver_reinit
+
+    # Run reload command to activate firmware:
+    # Note that mlx5 driver reloads the driver while activating firmware
+    $ devlink dev reload pci/0000:82:00.0 action fw_activate
+    reload_actions_performed:
+      driver_reinit fw_activate
diff --git a/Documentation/networking/devlink/index.rst b/Documentation/networking/devlink/index.rst
index 7684ae5c4a4a..d82874760ae2 100644
--- a/Documentation/networking/devlink/index.rst
+++ b/Documentation/networking/devlink/index.rst
@@ -20,6 +20,7 @@ general.
    devlink-params
    devlink-region
    devlink-resource
+   devlink-reload
    devlink-trap
 
 Driver-specific documentation
-- 
2.17.1