Patch series "liveupdate: Rework KHO for in-kernel users", v9.
This series refactors the KHO framework to better support in-kernel users
like the upcoming LUO. The current design, which relies on a notifier
chain and debugfs for control, is too restrictive for direct programmatic
use.
The core of this rework is the removal of the notifier chain in favor of a
direct registration API. This decouples clients from the shutdown-time
finalization sequence, allowing them to manage their preserved state more
flexibly and at any time.
In support of this new model, this series also:
- Makes the debugfs interface optional.
- Introduces APIs to unpreserve memory and fixes a bug in the abort
path where client state was being incorrectly discarded. Note that
this is an interim step, as a more comprehensive fix is planned as
part of the stateless KHO work [1].
- Moves all KHO code into a new kernel/liveupdate/ directory to
consolidate live update components.
This patch (of 9):
Currently, KHO is controlled via debugfs interface, but once LUO is
introduced, it can control KHO, and the debug interface becomes optional.
Add a separate config CONFIG_KEXEC_HANDOVER_DEBUGFS that enables the
debugfs interface, and allows to inspect the tree.
Move all debugfs related code to a new file to keep the .c files clear of
ifdefs.
Link: https://lkml.kernel.org/r/20251101142325.1326536-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20251101142325.1326536-2-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com [1]
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
03d3963464