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.. SPDX-License-Identifier: GPL-2.0
==============
Devlink Health
==============
Background
==========
The ``devlink`` health mechanism is targeted for Real Time Alerting, in
order to know when something bad happened to a PCI device.
* Provide alert debug information.
* Self healing.
* If problem needs vendor support, provide a way to gather all needed
debugging information.
Overview
========
The main idea is to unify and centralize driver health reports in the
generic ``devlink`` instance and allow the user to set different
attributes of the health reporting and recovery procedures.
The ``devlink`` health reporter:
Device driver creates a "health reporter" per each error/health type.
Error/Health type can be a known/generic (e.g. PCI error, fw error, rx/tx error)
or unknown (driver specific).
For each registered health reporter a driver can issue error/health reports
asynchronously. All health reports handling is done by ``devlink``.
Device driver can provide specific callbacks for each "health reporter", e.g.:
* Recovery procedures
* Diagnostics procedures
* Object dump procedures
* OOB initial parameters
Different parts of the driver can register different types of health reporters
with different handlers.
Actions
=======
Once an error is reported, devlink health will perform the following actions:
* A log is being send to the kernel trace events buffer
* Health status and statistics are being updated for the reporter instance
* Object dump is being taken and saved at the reporter instance (as long as
there is no other dump which is already stored)
* Auto recovery attempt is being done. Depends on:
- Auto-recovery configuration
- Grace period vs. time passed since last recover
User Interface
==============
User can access/change each reporter's parameters and driver specific callbacks
via ``devlink``, e.g per error type (per health reporter):
* Configure reporter's generic parameters (like: disable/enable auto recovery)
* Invoke recovery procedure
* Run diagnostics
* Object dump
.. list-table:: List of devlink health interfaces
:widths: 10 90
* - Name
- Description
* - ``DEVLINK_CMD_HEALTH_REPORTER_GET``
- Retrieves status and configuration info per DEV and reporter.
* - ``DEVLINK_CMD_HEALTH_REPORTER_SET``
- Allows reporter-related configuration setting.
* - ``DEVLINK_CMD_HEALTH_REPORTER_RECOVER``
- Triggers reporter's recovery procedure.
* - ``DEVLINK_CMD_HEALTH_REPORTER_TEST``
- Triggers a fake health event on the reporter. The effects of the test
event in terms of recovery flow should follow closely that of a real
event.
* - ``DEVLINK_CMD_HEALTH_REPORTER_DIAGNOSE``
- Retrieves current device state related to the reporter.
* - ``DEVLINK_CMD_HEALTH_REPORTER_DUMP_GET``
- Retrieves the last stored dump. Devlink health
saves a single dump. If an dump is not already stored by devlink
for this reporter, devlink generates a new dump.
Dump output is defined by the reporter.
* - ``DEVLINK_CMD_HEALTH_REPORTER_DUMP_CLEAR``
- Clears the last saved dump file for the specified reporter.
The following diagram provides a general overview of ``devlink-health``::
netlink
+--------------------------+
| |
| + |
| | |
+--------------------------+
|request for ops
|(diagnose,
driver devlink |recover,
|dump)
+--------+ +--------------------------+
| | | reporter| |
| | | +---------v----------+ |
| | ops execution | | | |
| <----------------------------------+ | |
| | | | | |
| | | + ^------------------+ |
| | | | request for ops |
| | | | (recover, dump) |
| | | | |
| | | +-+------------------+ |
| | health report | | health handler | |
| +-------------------------------> | |
| | | +--------------------+ |
| | health reporter create | |
| +----------------------------> |
+--------+ +--------------------------+
|
